The Changing Domestic Architecture of Kathmandu Valley
A thesis submitted to the
Graduate School
of the University of Cincinnati
in partial fulfillment of the
requirements for the degree of
Master of Science in Architecture
in the Department of Architecture and Interior Design
of the College of Design, Architecture, Art and Planning
2019
by
Ashna Singh
Bachelor of Architecture
Kathmandu Engineering College, Nepal, 2013
Committee Chair: Jeffrey Tilman
Committee Member: Thomas Bible Abstract
Kathmandu, the capital of Nepal, which is a small mountainous country that lies tucked between
India and China in South Asia, has had a rich heritage of vernacular architecture - with brick walls, intricate wooden lattice windows and doors, and clay tile roofs. The vernacular architecture is historically important and gives the place its architectural identity. However, in recent years building culture has shifted towards the contemporary construction method of Reinforced Cement
Concrete (RCC) Construction. With the earthquake of April 2015, and the destruction of millions of dollars’ worth of infrastructure, people are now more than ever inclined to build in RCC as the new construction caters to the new needs of the people; The RCC constructions also allow openness and inclusion of new spaces that the traditional forms would have otherwise hindered.
The new construction is also very heavily influenced by the global modernization phenomenon, where especially developing countries, like Nepal, find themselves in the middle of the pull of the modern and developed world versus the need to be rooted and further the historic way of life and its association with the character of the country, its identity, and its uniqueness. The purpose of this thesis is to explore a possible middle ground where the best of both could be incorporated.
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Acknowledgment
I would like to thank my advisor Professor Jeffrey Tilman for his support and guidance in this thesis. His words of encouragement and positivity have kept pushing me forward to complete my thesis. I would also like to thank my committee member Professor Tom Bible for his input and insights in my research and thesis. His supervision has helped drive the thesis forward and helped me understand the depth of my research.
Special thanks to Professor Rebecca Williamson for always being a helpful guide throughout the time I spent at the University of Cincinnati. I would also like to extend my sincere gratitude to the
University of Cincinnati for providing all the necessary sources for successful completion of this thesis.
My greatest appreciation to my family in Nepal, especially my father, Jagadishwar Man Singh, and mother, Babita Singh, who have always been my greatest strength and source of inspiration.
Lastly, I would like to thank my sister, Nishika, for her encouragement and unwavering belief in me.
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Table of Contents
Abstract ...... ii
Acknowledgment ...... iv
Table of Contents ...... v
List of Figures ...... vii
1. Introduction ...... 1
2. Vernacular Architecture ...... 10
2.1. Settlement Pattern ...... 11
2.2. Proportion and Symmetry ...... 13
2.3. Spatial Layout: ...... 14
2.4. Construction Techniques ...... 16
2.4.1. Foundation ...... 16
2.4.2. Walls ...... 17
2.4.3. Floors ...... 18
2.4.4. Roof...... 19
2.5. Building Materials ...... 20
2.6. Windows and Doors ...... 20
3. R.C.C. Structure...... 23
3.1. Foundation ...... 24
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3.2. Frame ...... 25
3.3. Walls ...... 26
3.4. Roof ...... 28
3.5. Ownership and Spatial Layout ...... 28
3.6. Settlement Pattern ...... 30
3.7. Building Materials ...... 31
4. Thermal Comfort ...... 32
5. Seismic Resilience ...... 37
5.1. History of Earthquakes in Nepal ...... 39
5.2. Vernacular Architecture – Seismic ...... 40
5.3. RCC Structure - Seismic...... 46
5.4. Implication ...... 51
5.4.1. Ways to strengthen the vernacular architecture ...... 51
5.4.2. Ways to strengthen RCC construction ...... 54
6. Conclusion ...... 55
Bibliography ...... 66
Appendix ...... 69
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List of Figures
Figure 1 Topographical Map of Nepal ...... 1
Figure 2 Section showing the change in land elevation from the plains to the mountains ...... 2
Figure 3 View of the traditional high vernacular architecture of Kathmandu Valley ...... 5
Figure 4 Gaddi Baithak built in the Classical Revival style with columns and pediments ...... 6
Figure 5 The Growth in Kathmandu showing the increase in built space from 1980 to 2010 ...... 7
Figure 6 Images of Domestic Vernacular Architecture of Kathmandu Valley...... 10
Figure 7 Houses built around a courtyard with a sunken water spout ...... 11
Figure 8 Image showing courtyard planning of Newari buildings ...... 12
Figure 9 Top: Elevation of Newari Architecture. Bottom: Typical Plan of Newari Architecture 13
Figure 10 Section of a typical Newari house in Kathmandu ...... 14
Figure 11 Section showing the division of spaces ...... 15
Figure 12 The bay window and open ground floor aiding the view of the various procession on the street ...... 15
Figure 13 Section showing the pure and impure spaces ...... 16
Figure 14 Foundation of a Newari House ...... 17
Figure 15 The different layers of brick used to construct the wall ...... 17
Figure 16 Section of the hanging roof ...... 19
Figure 17 Different types of wooden windows used in Nepali architecture ...... 21
Figure 18 Different types of wooden doors used in Nepali architecture ...... 22
Figure 19 New Construction Houses in Kathmandu Valley ...... 23
Figure 20 View of Pad Footing, Stepped Footing and Sloped Footing ...... 24
Figure 21 Section of an RCC Sloped Footing ...... 24
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Figure 22 Network of beam and Column that form the frame in the building ...... 25
Figure 23 Section of a column showing the steel bars and concrete cover ...... 25
Figure 24 Model of a one-way slab ...... 26
Figure 25 Model of a two-way slab ...... 26
Figure 26 Wall Section of an RCC construction building ...... 27
Figure 27 From top left in a clockwise direction – Single family private house, Private house with lower floors rented out, Private house with the lower floor for retail space ...... 29
Figure 28 Placement of rooms in a private modern RCC building ...... 29
Figure 29 Vertical stratification of the house to accommodate the private house and the rented floor...... 30
Figure 30 Aerial view of Kathmandu Valley showing the haphazard expansion...... 31
Figure 31 Use of RCC and Brick in construction the outer shell of the structure ...... 31
Figure 32 Climatic Data of Kathmandu Valley through the year ...... 32
Figure 33 Working of thermal mass during the summer ...... 33
Figure 34 Working of Thermal Mass during the Winter ...... 34
Figure 35 Left: The spatial arrangement aiding the internal temperature control, Right: Flow of breeze through the vernacular building aiding in cooling the building...... 35
Figure 36 Overheating on the top floors in summer...... 35
Figure 37 Center of Mass coincides with Center of Resistance ...... 40
Figure 38 Symmetrical Elevation of the vernacular architecture ...... 40
Figure 39 Section showing all the wooden elements in the vernacular building...... 41
Figure 40 Isometric view of the roof and the pillars that use timber in the vernacular building .. 42
Figure 41 Double frame windows of the Newari Architecture...... 42
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Figure 42 Section of Newari Vernacular Building showing the soft story ...... 43
Figure 43 Open Front of a vernacular building creating torsion due to unequal perimeter stiffness
...... 43
Figure 44 Section of a vernacular house showing the vertical mass irregularity ...... 44
Figure 45 Weak corners resulting in cracks and collapse of buildings ...... 45
Figure 46 Image showing the construction of RCC building ...... 46
Figure 47 Building's reaction to earthquake force with uniform stiffness and different stiffness 47
Figure 48 Buckling caused by soft story ...... 48
Figure 49 Examples of vertical and plan irregularity in the RCC buildings ...... 49
Figure 50 Weak story induced by uneven story height...... 50
Figure 51 Placement of Water Tanks on the rooftop ...... 50
Figure 52 Addition of braces on the soft story to increase the stiffness...... 52
Figure 53 Right: Bracing the corners to strengthen them...... 52
Figure 54 Different Methods of reinforcing the corners ...... 53
Figure 55 Slender Buildings in Kathmandu...... 54
Figure 56 An RCC construction that is built with RCC frame and masonry infill, with symmetrical in elevation, regular plan, and bands ...... 60
Figure 57 Sloped roof with cut out for terrace space ...... 62
Figure 58 New Construction adapting the vernacular architecture and its principles...... 64
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1. Introduction
Nepal is a small mountainous country in South-Asia that lies tucked between India and China.
Even though the country is only 200km wide, the elevation of the land goes from as low as 72m a.s.l. (above sea level) all the way up to 8848m a.s.l., the highest point in the world. This varied topography in a relatively small width is the result of the Indian peninsula crashing into the
Eurasian plate. This also means that within the very narrow width of around 200km, the land changes from flat to hilly to mountainous.
Figure 1 Topographical Map of Nepal
(Source: https://upload.wikimedia.org/wikipedia/commons/2/23/Nepal_topo_en.jpg) The varied topography has broadly been divided into three regions - the Terai, Pahad, and Himal, or the plains, hills, and mountains. As the name suggests, the plains are fertile plain lands that are very suitable for agriculture. The hilly region consists of hills and medium height mountains, while
1 the mountainous regions are mountains that are higher than 4000m. The climate changes from sub- tropical in the plains to cool temperate in the hilly areas, and alpine in the mountainous regions.
Figure 2 Section showing the change in land elevation from the plains to the mountains
(Source: Shock Safe Nepal)
Even though Nepal is a small country, many tiny kingdoms were united to create it. In 1765 AD,
Nepal was united into a kingdom by King Prithvi Narayan Shah who went into battles with the various small kingdoms spread around the area1. Today, Nepal is a democratic republic and has a population of roughly 29 million spread over 147, 181 km2. There are more than twenty ethnic groups in Nepal with different cultural, social and religious backgrounds.2 The most predominant religion in Nepal is Hinduism, however, there are people who follow Buddhism, Christianity,
Islam, and Kiratism3 as well. Roughly 80% of the people in Nepal are Hindus, 10% are Buddhists, and the remaining 10% are divided into Muslims, Christians, and Kirats.4
1Mary Slusser, Nepal Mandala - A Cultural Study of the Kathmandu Valley Volume I, (New Jersey, Princeton University Press, 1982) 2 ibid 3Kiratism is a religion that is predominantly followed by the Kirati ethnic group of Nepal and is closely associated with Tibetan Buddhism. 4 National Population and Housing Census 2011 (National Report). Government of Nepal, National Planning Commission Secretariat, Central Bureau of Statistics, Kathmandu, Nepal
2
The caste system in Nepal is a stratification of people according to their profession and are divided into ‘touchable’ or the pure caste and the ‘untouchable’ or the impure caste. Within the pure castes, the priests and goldsmiths are the highest in the system, followed by traders and craftsmen, farmers, potters, florists, barbers, ironsmith, oil presser, and funeral priests in a descending order of hierarchy of pureness. On the other end of the spectrum, the impure castes consist of butchers, tailors, shoemakers, clothe washers, fishermen, and sweepers and cleaners.5 The stratification according to the caste is prevalent even in the planning of the city, with the gods and temples situated at the city core, and the palaces and the priests’ dwelling surrounding the city core. The dwellings of other castes progressively surround them in a concentric pattern, with the dwellings of the lowest caste placed farthest from the city core and closest to the rivers and cremation sites.6
The primary source of economy for Nepal is agriculture and tourism, with hydropower having the potential to develop into a large source of income. While agriculture and processing agricultural goods account for the largest part of the GDP, during peak tourist season, i.e., the fall months of
September to November, tourism also contributes significantly to the GDP of the country.
Advancement in technologies has made communication and transportation more accessible than ever, and it is no wonder then that the world is sprawling and yet consequently shrinking - as several societies and cultures meld and fuse together. The world seems to be inadvertently moving
5 Mary Slusser, Nepal Mandala - A Cultural Study of the Kathmandu Valley Volume I, (New Jersey, Princeton University Press, 1982) 6 Aranha, J. L., A Comparison of Traditional Settlements of Kathmandu and Bali, Traditional Dwellings and Settlements Review, Vol. II, 35 – 47, 1991.
3 towards a global style of living, as people and businesses have transcended borders and truly become international.
However, moving towards a global approach gives rise to the conflict of what happens to the cultural and regional identity that people have associated themselves with over the course of time.
Certainly, that must also play an equal role in shaping up the world?
This conflict has manifested itself in the architecture of Nepal as well, where the architectural style and identity of the country struggles under rapid globalization and natural disasters. On one hand, is the need to preserve what is uniquely Nepali, and on the other, is the need to move ahead and catch up with the world. The vernacular architecture holds within itself significant heritage and cultural references that have been passed on and preserved for generations. But as more and more vernacular buildings are replaced with the Reinforced Cement Concrete (RCC) structures, the shift from vernacular to the RCC structure puts the cultural identity of the country at risk.
Similarly, on the other end of the spectrum is the debate on whether trying to hold onto the vernacular architecture makes us stagnant, and stops us from progressing into the future? Is infrastructure the only way to denote modernization of the society and country?
The start of RCC construction only started after the country was opened to the world in the 1950s, but today, in less than a century, 28% of all houses are built in the RCC style of construction7, with the numbers only rising every year. There are many factors like a natural disaster, migration into
7 National Population and Housing Census 2011 (National Report). Government of Nepal, National Planning Commission Secretariat, Central Bureau of Statistics, Kathmandu, Nepal.
4 the city, change in lifestyle, and modernization, among others that have contributed to the construction and reconstruction of the buildings in the RCC style.
Figure 3 View of the traditional high vernacular architecture of Kathmandu Valley
(Source: http://www.gloriousindiatours.com/destination-details.php?packageId=4)
As Nepal lies in an earthquake-prone zone, destruction resulting from an earthquake has always been an issue. The prior reconstructions had however always been done in vernacular style, but now, with exposure to RCC construction, the vernacular buildings are rapidly being replaced by
RCC buildings. The assurance that the RCC construction is better equipped to handle earthquakes in the future keeps drawing people to it.8 The capability of the RCC structure to withstand an earthquake and the tests of time have been so deeply ingrained in the Nepalese society that in the
Nepali language, the old vernacular houses are called Kachha Ghar meaning temporary or frail house, whereas the RCC houses are called Pakka Ghar meaning permanent or sturdy houses.
8 Pant, Shaswant, Newari architecture in Kathmandu: ‘Old and weak’ buildings are also part of heritage. (http://english.onlinekhabar.com/newari-architecture-in-kathmandu-old-and-weak-buildings-are-also-part-of- heritage.html)
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The wave of change can also be accredited to the de facto Rana rulers. Although the country was closed to the outside world, the
Ranas would often travel to Europe on their many diplomatic trips. The grandeur of Europe and its architecture had a clear impact on
Figure 4 Gaddi Baithak built in the Classical Revival style with columns and them and once they traveled back to pediments Nepal, the European classical style (Source: https://3.bp.blogspot.com/-si- of construction was imitated in J4rDwnlc/V7fKl5OzbzI/AAAAAAAAIVc/_D- 1D0pFBvcz7IjhOHQcAZYn6pWxncaKQCLcB/s1600/Gaddi-Bhaithak.jpg) Nepal. The Ranas built their palaces in the Neoclassical style with columns and pediments that distinguished them from the rest of the country. The massive constructions in a completely new style helped them establish their strength and power in the eyes of the Nepali people as these structures proved to be a sign of wealth and knowledge.
Another factor that has catapulted the RCC construction is the civil unrest in the country. The
Nepali government radically shifted from a Monarchy to a Democracy in 2006, which was filled with many guerilla wars and riots all over the country.9 The capital was the only city that was
9 Whelpton, J. A History of Nepal. Cambridge: Cambridge University Press. 2005.
6 relatively safe.10 This made anyone who could afford to leave their home and move to the city, move to the city at a rapid rate. This coupled with the longstanding prospect of better job opportunities and amenities in the city has attracted many Nepalese from the rural areas into the urban core of the Kathmandu Valley. This sudden influx of population has resulted in a 61.23% growth in population in the Kathmandu over the past decade.11
The inundation of people has consequently put a strain on the infrastructure of the capital as land is scarce and accommodation insufficient. This strain then meant that the capital needed more infrastructure to accommodate the addition of people. This led to many construction companies investing in the construction of high-rise apartments. The massive influx of people not only introduced a new building typology, but it also changed the spatial arrangement of the residential architecture. The average house which was once constructed for a single family is now constructed
Figure 5 The Growth in Kathmandu showing the increase in built space from 1980 to 2010
(Source: Impact of Urbanization and Climate Change on Urban Flooding: A case of the Kathmandu Valley – Journal of Natural Resources and Development)
10 In comparison to other cities and villages in Nepal, where the war took many lives and livelihood away from people. There were more security personnel and army on patrol in the capital than anywhere else in the country. 11 National Population and Housing Census 2011 (National Report). Government of Nepal, National Planning Commission Secretariat, Central Bureau of Statistics, Kathmandu, Nepal.
7 with the intention of renting out the lower floors to the migrant population. The migrants usually stay in the rented spaces until they can build their own homes – this took anywhere from a year to even a decade. As every migrant that comes into the city plans to build their own house eventually, the added upsurge in construction is inevitable; thus, the city is expanding and newer constructions gaining more momentum now more than ever.
The migration process, however, is not limited to people moving from the outskirts into the city, many Nepali also migrate outside of the country – mostly to India, the Middle East, USA, Canada and Australia for studies and work. About 25% of the households have at least one member absent or living abroad.12 The staggering number of people that are outside the country has subsequently propelled the wave of modernization and brought a major shift in the ideals, principles, and lifestyle of the Nepalese. This change has also been a contributing factor for people wanting to abandon the vernacular and shift to the modern style of buildings.
A typical family in Nepal consists of the grandparents, parents, children, daughters-in-law, and grandchildren all living under the same roof. Typically, the house and properties get divided among the sons (daughters aren’t usually included) when the parents die. The property is not always divided equally, and a single house can be divided into uneven sections because of this division.
Thus, these various factors have been shaping and reshaping the urban fabric of Kathmandu where today, there are two dominant types of residential architecture - the vernacular brick masonry construction and the contemporary RCC construction, with the RCC on the verge of overtaking
12 Ibid.
8 the vernacular. For the country to not lose its architectural heritage, there is a dire need for the two to work together for a more resilient and reflective construction culture that can promulgate the ideals and characters of vernacular architecture, while maintaining the fluidity and modernity of the RCC.
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2. Vernacular Architecture
Vernacular architecture is the result of hundreds of years of optimization to provide a comfortable shelter in a local climate using available materials and known construction technologies.13 It can be argued that the very beginning of architecture was also the beginning of vernacular architecture.
The very first shelter was built out of the human need to protect themselves from the hardships of the weather and the imminent danger from the wild animals. Although when it all began and what
Figure 6 Images of Domestic Vernacular Architecture of Kathmandu Valley.
(Source: Picture 1: https://www.researchgate.net/profile/Arun_Menon3/publication/299865925/figure/fig2/AS:489778807349249@149378377581 3/Example-of-a-Newari-house-from-Kathmandu-credits-Esmeralda-Pauperio-Xavier-Romao.png, Picture 2: https://farm1.static.flickr.com/698/21835451516_fd4e811ebe_b.jpg Picture 3,4: http://english.onlinekhabar.com/newari- architecture-in-kathmandu-old-and-weak-buildings-are-also-part-of-heritage.html Picture 5: https://samirpathak.myportfolio.com/kirtipur-nepal)
13Susanne Bodach, Werner Lang, Johannes Hamhaber, "Climate responsive building design strategies of vernacular architecture in Nepal", Energy and buildings Vol. 81 (2014): 227-242
10 exactly comprised the very first building is not very clear, it is certain that the first building was most likely built with the help of the materials that were available in the surroundings.
Similarly, the vernacular architecture of Nepal has been influenced by the materials that are available, the climate, the culture and the people.
There are many character-defining traits of the vernacular architecture of Kathmandu, also known as the Newari architecture. These traits are not only responsible for giving the vernacular architecture its unique characteristics, but it is also what distinguishes them.
2.1.Settlement Pattern
The traditional settlement of Kathmandu Valley has been a compact one, with buildings built around a courtyard - traditionally known as a bahal or bahil. They emulate the mandala/mandap - a religiously significant symbol in Hinduism and Buddhism that represents the universe.
The courtyard is a religiously and socially significant space as the community deity is placed here, it is also a place for the inhabitants to gather and interact with each other, a place for children to play, for fruits and vegetables to be dried, clothes to Figure 7 Houses built around a courtyard with a sunken water spout be washed, and various other social (Source: http://thd.com.np/wp-ontent/uploads/2014/11/11.jpg and cultural activities. The courtyard is thus an important part of the daily life, and during special
11 occasions, the courtyard also hosts a variety of religious events like the traditional dances and feasts.
Figure 8 Image showing courtyard planning of Newari buildings
(Source: http://www.theartofencouraging.com/wp-content/uploads/2015/02/from-babermahalrevisitedCOM.jpg)
In the traditional settlement, the courtyard was inhabited by people of the same caste group, and consequently occupation. Today, there is no such social regulation guiding who resides in the dwellings surrounding the courtyard. The disparity only grows as spaces are occupied by migrants from all over the country with different castes and religions.
The settlement plan of the city was also largely determined by the caste system. The higher the caste of the people, the closer to the city core they resided. This meant that the noblemen and businessmen could build their homes around the periphery of the castle, the middle-class pure people could build in the area outside the noble class’ homes, while the impure castes were only allowed to build close to the river and away from the city core.
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2.2.Proportion and Symmetry
The vernacular buildings are almost always constructed in a square or a rectangular plan. The rectangular proportion of the sides being 2:1 in most cases. The symmetry of the layout is followed through in the façade as well.
Figure 9 Top: Elevation of Newari Architecture. Bottom: Typical Plan of Newari Architecture
(Source: https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS- Fu4niy5vYtpkxNmahEeInMQKl_nVh574iPbnE2sTgSSmYbXn)
The door is always placed at the center, or placed symmetrically in the façade, while the windows are placed symmetrically on the facade. The most common placement of the windows is on both the sides of the central axis, with one placed along the axis.
The regular proportion and layout of the building play an important role in reflecting the culture of the Nepalese society as squares and rectangles are considered as auspicious shapes that help bring prosperity to the inhabitants of the house.
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2.3.Spatial Layout:
The vernacular building is a vertically planned building, with the placement of the floors reflecting the lifestyle of the people. The ground floor is usually a store/shop, the first floor is used for sleeping, the second floor is a common living space and the top floor has kitchen, dining and worship room. As most of the natives of Kathmandu were businessmen or farmers, the ground floor was most useful for placing a shop/store, the living room was placed higher to give the
Figure 10 Section of a typical Newari house in Kathmandu
(Source: Gutschow, Niels. Newar Towns and Buildings. pg 135)
14 inhabitants a higher vantage point to view the various processions that would take place in the street during the myriad of festivals. The kitchen was placed on the top floor for convenient and direct smoke outlet. Similarly, the windows on the living room were specifically designed to be big and sloped for easy viewing of the processions on the street.
Figure 11 Section showing the division of spaces
(Source: author)
Figure 12 The bay window and open ground floor aiding the view of the various procession on the street
(Source: author)
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A house is a sacred place and thus tends to be divided into pure and impure sections. The floors are placed in ascending order of purity with the lowest floor being the least pure and the top floor being the purest. The kitchen and the worship room are the purest place in the house and is only accessible to the members of the house. Even the kitchen is divided into pure and impure areas, with the cooking and storage area considered as Figure 13 Section showing the pure and impure spaces the purest area, while the floor where people eat, (Source: author) along with the area where the dishes are cleaned are considered an impure area. This concept of places and people that are pure and impure has existed for centuries and has been a very integral part of the society and its functionality.
2.4.Construction Techniques
The construction techniques of the vernacular architecture of Kathmandu is one of the many things that distinguishes it from the other vernacular architecture of the country. The vernacular architecture is primarily a load-bearing brick masonry system. Some of the elements of construction are discussed below:
2.4.1. Foundation
The vernacular houses are built in load-bearing masonry construction – this means that
the buildings do not have columns and beams, i.e., a frame, to support the weight of
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the building. It is instead supported by the walls and floors, which are in turn supported
by the foundation of the building.
The foundation of the house is mostly shallow – about 40 to 60 cm deep for a three-
story building.14 The footing is
stepped and about 70cm wide. The
very base of the foundation is
constructed using large cobbles,
which is then followed by the
brickwork that continues upward
as walls. Mud mortar is used to
Figure 14 Foundation of a Newari House hold the cobbles and bricks in place. (Source: Gutschow, Niels. Newar Towns and Buildings. pg 133) 2.4.2. Walls
The walls in the vernacular buildings are a
continuation of the foundation. The thickness of
the wall varies as it goes from bottom to top.
They vary from their thickest at 75cm to their
thinnest at 45cm15 - the walls are tapered to
Figure 15 The different layers of brick reduce the weight of the wall itself on the used to construct the wall
foundation. (Source: Gutschow, Niels. Newar Towns and Buildings. pg 133)
14 Gutschow, N, Kolver, B. Shresthacarya, I. Newar Towns and Buildings - An Illustrated Dictionary. (Germany, Hans Richarz Publikations, 1987) 15 Beckh, Matthias Traditional Construction Techniques of the Newars at the Itum Baha Monastery in Kathmandu. (Kathmandu: Kathmandu Valley Preservation Trust, 2002)
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The wall is constructed using three types of bricks; the fair-faced tapered bricks are
used in the façade, regular bricks are used for the interior wall, while rubble and
irregular bricks are used as infill between the two layers. Traditionally, the mortar used
is mud mortar.
Because the vernacular houses are built in load-bearing fashion, the walls need to be
thick enough to bear the load of the wall and the building. The thickness of the wall
also means high thermal mass16, which helps in maintaining thermal comfort.
In cases where the ground floor is used as a shop, timber arcades are used as part of
the front façade of the ground floor to provide easy access between the outside and the
inside. Timber pillars and beams are also used as partition walls on the upper floors.
2.4.3. Floors
The floors in the Newari architecture are constructed by using closely spaced joists,
which are covered using wood planks, and finished with approximately 10cm thick
layer of fine yellow clay. The floor joists are supported by wooden wall planes that are
placed in the wall. Wooden pegs are used to hold the joists in place.17
16 Thermal Mass refers to the ability of any material to store heat. During, the day, the walls and floors continuously absorbs heat at their surface and conducts it inwards, which gets stored in the mass until it is exposed to cooler air of the evening/night. 17 Beckh, Matthias Traditional Construction Techniques of the Newars at the Itum Baha Monastery in Kathmandu. (Kathmandu: Kathmandu Valley Preservation Trust, 2002)
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2.4.4. Roof
The projecting roof in a Newari building is one of its most distinctive character of the
vernacular architecture and is always pitched. The roof, which typically projects about
a meter from the façade, is constructed using purlins and the ridge beams, and usually,
has a slope of 30 degrees. The roof is topped by placing wooden planks and finished
using mud mortar and clay tiles. The eave purlins are supported by brackets – which
can sometimes be carved. The brackets are usually at 45 degrees and spaced about 2m
apart. The brackets rest either on the brick cornice in the wall or sometimes on a
wooden beam.18
Symbolically, they are supposed to represent the mountains that can be seen from the
valley. Practically, the overhang pitched roof helps with better water runoff during the
monsoon season, helps protect the brick wall from the same rain and provides shade
during the hot summer months.
Figure 16 Section of the hanging roof
(Source: Gutschow, Niels. Newar Towns and Buildings. pg 158)
18 ibid
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2.5.Building Materials
The three major building materials that are used in the construction of the vernacular architecture are clay brick & tile, wood, and stone.
The alluvial soil in the valley creates an abundance of clay, which is the primary component for manufacturing bricks and tiles. The bricks are mostly used for the construction of the walls, while the clay tiles are used as roof cladding. The clay bricks used are of three types: oven-baked bricks or dachi appa, sun-dried or the kachi appa, and finishing bricks called the chika appa
As Kathmandu is surrounded by dense forests, there is an abundance of timber which is used to construct for post and lintels, windows, doors, roof rafters, and wall ties.
Because the primary materials used in the vernacular architecture are available readily in the valley, they are not only economically cheaper, and sustainable, they also reflect the environment and ecology of the valley. The use of bricks and wood give the vernacular architecture its characteristic warm and earthy tone and help maintain its tie with the earth - which is again in symbiosis with the people and their devotion to religion.
2.6.Windows and Doors
The doors and windows in the vernacular buildings are two of its most intricate elements. They are usually made of Sal Tree or Shorea Robusta, or Simal tree or Bombaxceiba, depending on the type of window being constructed. The windows are especially wide-ranging in their styles, and a variety of carved windows are used in the vernacular buildings - from a simple lattice window called the tikijhya to more elaborate windows like sajhya and gajhya which can have three to five bays. The windows are handmade, and the craft can take half a decade to master.
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Figure 17 Different types of wooden windows used in Nepali architecture
(Left: single panel lattice window or the tikijhya. right: three panel wooden lattice window or sajhya)
(Source: Left - https://i1.trekearth.com/photos/121678/kathmandu_durbar_square2a.jpg. Right - picture taken by author)
Simple lattice windows used in the lower floors are usually smaller in size, which helps maintain the strength of the wall by minimizing the puncture in the wall – this can make the building more seismically resistant. The lattice design of the window was a result of people’s desire for more privacy yet their need for ventilation and light. The lattice window accomplishes all three needs by not only obstructing a direct visual link, but also allowing easy air flow and moderate sunlight in the house. As the Newari society is a very conservative society, the privacy the windows provided were as important as the functionality of the windows.
Another important aspect that the windows reflect are the religious festivals and their importance.
The larger window on the upper floor not only allows ample amount of sunlight and air flow inside the building, it also provides visual access to the street below where the processions with people and chariots take place. Besides its function, the larger windows also give the opportunity to showcase the wooden craftsmanship of the Newari people.
21
Figure 18 Different types of wooden doors used in Nepali architecture
(Source: https://i.pinimg.com/originals/8c/d0/ac/8cd0acad7d25590252e8e9dffaa255c4.jpg, https://c1.staticflickr.com/5/4508/37859422416_e13f4383ca_b.jpg, http://www.advzambuling.com/uploads/galleries2/655a4637- edit-edit-edit-1404118559.jpg ) The doors are the entryway to the house and therefore are considered to be a very auspicious element of the building. The doors are always double-leafed and made with elaborate frames and even more elaborate panels. The panels are adorned with various icons and images of different elements that are considered auspicious like carvings of celestial bodies, gods, eyes or Gagris19.
Sometimes, the doors are topped with decorative lintels.
19Gagri is a traditional brass vase used to transport and hold water from the water spout into the house. These vases are placed outside the house on either side of the door, filled with water and flower to welcome the guest and gods into the house.
22
3. R.C.C. Structure
The contemporary style of construction in Nepal is dominated by the Reinforced Cement Concrete
Construction or the RCC construction. This newer method of construction was introduced around the 1950s but has already taken over as the predominant form of construction in the city. The RCC structures are not only a newer method of construction, but they are also structurally and aesthetically different from the vernacular.
Figure 19 New Construction Houses in Kathmandu Valley
(Source: Left: Flickr.com/asieman, Right: www://gharbazar.com) After the earthquake of 1934, reconstruction was primarily done using brick and mortar. Since the introduction of RCC in Nepal, the reconstructions thereafter have also been dominated by RCC.
Today, many residential buildings are either bricks with cement mortar or moment resisting concrete frame with masonry infill.
The RCC structure can be divided into two parts, the part below the ground or the foundation, and the part above the ground or the moment resisting frame, i.e., the columns, the beams, and the slabs.
23
3.1.Foundation
The most common foundation in RCC buildings in Kathmandu are the isolated shallow foundations, or footings. The footings transfer the load from the columns and beams to the ground.
The shallow foundation is constructed with reinforcement bars, cement aggregate mortar and stirrups. The most common types of isolated shallow footings are:
1. Pad Footing
2. Stepped Footing
3. Sloped Footing
Figure 20 View of Pad Footing, Stepped Footing and Sloped Footing
(Source: author)
In cases where the soil is loose and does not have adequate load bearing capacity, either a pile foundation or a raft(slab) foundation is used. There are very limited cases of raft or pile foundation being used in a domestic building in Kathmandu.
Figure 21 Section of an RCC Sloped Footing
(Source: author)
24
3.2.Frame
The main structure that holds the building upright is the moment resisting frame – which consists of the RCC columns and beams, and a horizontal diaphragm, or the slab. The load of the building is transferred from the slab to the beams, which transfers the load to the columns, which then gets
Figure 22 Network of beam and Column that form the frame in transferred to the footings, which finally the building transfers it to the ground. (Source: author)
3.2.1. Beams and Columns
Beams are the horizontal load-bearing elements and columns are the vertical load-bearing elements of the structure. The size of the columns and the beams, along with the specification of the size and number of rebars and stirrups used help determine the strength of the beams and columns. The steel rebars are encased in cement concrete casing, giving the element both strength and ductility. Figure 23 Section of a column showing the steel bars and concrete cover 3.2.2. Slab (Source: author) The slabs are the horizontal diaphragms that spans across the building. Structurally, they are usually 4” to 6” in thickness, with added thickness at the ground floor for moisture and temperature insulation and added thickness on all floors
25 depending on the finishing materials used. Structurally, there are two types of slabs namely – one- way slabs, and two-way slabs.
3.2.2.1.One-Way Slab
In a one-way slab, the loads are carried in a single direction to the joists or beams, which carries the loads to other beams, girders, columns, or walls. It is comparable to a wooden floor in a house, in which the floor transmits loads to perpendicular floor joists, which carry the loads to supporting beams, and so on. Figure 24 Model of a one-way slab (Source: author)
3.2.2.2.Two-Way Slab
In a two-way slab structure, the loads applied to the roof and the floor are transmitted in two directions to the columns by the beams, girders, columns or walls.
Figure 25 Model of a two-way slab 3.3.Walls (Source: author) The walls are the vertical elements of the structure, in most cases, the walls are masonry infill – i.e. brick and cement mortar, with a very few cases of concrete blocks being used. There are also few cases of curtainwalls being used in domestic RCC buildings.
26
The wall surface on the facade is either left un-rendered, plastered or painted and plastered. The color of the façade is determined by the owner in most cases resulting in the colorful urban fabric of Kathmandu today.
Although not responsible for carrying the load of the building, walls are accountable for the stiffness of the structure and its resistance to earthquakes. A uniform wall construction with similar openings ensures an equal stiffness of the structure.
Figure 26 Wall Section of an RCC construction building
(Source: author)
27
3.4.Roof
The choice of the roof is dependent on the owner and/or the architect, however, most new constructions are flat-roofed, with a decorative pediment added on the façade sometimes. The flat roof serves as a terrace and is used for many purposes, like sunbathing, social events and get- togethers, for drying out clothes and food in the sun, as a place to keep water storage tank etc.
3.5.Ownership and Spatial Layout
Perhaps, one of the most important matters to consider while categorizing the RCC constructions of Kathmandu is the ownership of the structure. Broadly, the domestic architecture can be divided into two kinds based on who built them:
1. Private houses built by the owner.
2. Private sector housing and apartment complexes.
The private houses can further be divided into:
1. Private house for one family
2. Private house with lower floors built for renting
Private houses can also be divided based on whether it was constructed by an architect with supervision from an engineer, or if it was constructed by a general contractor without any involvement of an engineer or an architect.
Private buildings are built anywhere from one story all the way up to five-six stories. Whenever possible, the lowest floor is rented out by business owners to put up their shop, and the top floor or floors are used by the owner. The remaining floors in between are usually rented out. Thus, the spatial arrangement of a building is based on the ownership and its use.
28
Figure 27 From top left in a clockwise direction – Single family private house, Private house with lower floors rented out, Private house with the lower floor for retail space
(Source: https://www.gharjagganepal.com) The spatial layout of a building depends on the owner and the purpose of the building. Usually, they can be categorized based on whether they were made to be a family home, or a home with provision for renting the lower floors.
The family home usually is built with the living areas, kitchen and the guest Figure 28 Placement of rooms in a private modern RCC building area on the ground floor, while the (source: Author)
29 bedroom and personal spaces are placed on the top floor, with the worship room placed at the topmost space in the house.
Houses built for renting are built like apartments with usually each floor rented out to a tenant, and the owner taking up the top floors for dwelling. Depending on whether the building faces a vehicular road, the ground floor may be rented out for businesses and/or storefronts. Figure 29 Vertical stratification of the house to accommodate the private house and the rented floor.
(Source: author)
Regardless of the type of building, almost all buildings have a terrace on the top floor. As space becomes scarcer, the courtyards are decreasing, and with every open space being used for construction of another building, terrace has substituted the courtyard as open space for daily and social activities. Everything from drying clothes, to foods, and social gatherings occur in a terrace.
Open space is an important space for the Newari community, as they have many festivities and feasts throughout the year. It is also the place where the water storage tanks and solar panels for heating waters are situated in the building.
3.6.Settlement Pattern
Massive influx of people has resulted in an uncontrolled expansion of the city. While there have been plans to keep the expansion regulated, planning codes rarely get implemented in Kathmandu.
30
The result is an organic but haphazard expansion of the city. The planned courtyards of the yesteryears have been replaced by narrow streets and minimal open spaces.
Figure 30 Aerial view of Kathmandu Valley showing the haphazard expansion
(Source: www.flickr.com/fengweiphotography)
3.7.Building Materials
The three main building materials used in modern constructions are brick, concrete, and steel.
As in the case of vernacular architecture, the bricks that are used in the constructions are manufactured in the country, while the steel bars and cement are either manufactured in Figure 31 Use of RCC and Brick in construction the outer shell of the structure Nepal or imported from India. (Source: https://www.microaidinternational.org/single- post/2016/06/02/Nepal-House-Project)
31
4. Thermal Comfort
Vernacular architecture of Nepal is highly influenced by culture, geographical diversity, local building materials, and climate. Nepal has a drastic difference in altitude which has resulted in a variety of climatic zones within the small area of the country. Because of this variety in climatic conditions and weather patterns, various strategies have been adopted for climate responsive designs in the vernacular architecture of Nepal. The same is also true for the vernacular architecture of the Kathmandu Valley.
Kathmandu lies in the warm temperate climate; the seasons are divided into spring, summer, monsoon, and winter. The temperature during summer and winter does not vary drastically. As can be seen from the graph, the temperature in summer ranges from high 28-29C to a low of about 20C, while winter sees a high of about 18C to a low of 2C.20 The total rainfall in the country can be about 1400mm, with up to
360mm of rain in July during the peak of monsoon.21
Because the temperature is not very drastic, thermal comfort is obtainable using thermal mass. The high thermal mass of walls and floors helps in retaining the heat and dissipating Figure 32 Climatic Data of Kathmandu Valley through the year accordingly to control the internal temperature of a building. (Source: Bodach, Susanne, Climate responsive building design strategies of vernacular architecture in Nepal)
20 Susanne Bodach, Werner Lang, Johannes Hamhaber, “Climate responsive building design strategies of vernacular architecture in Nepal”, Energy and buildings Vol. 81 (2014): 227-242 21 https://www.climatestotravel.com/climate/nepal
32
Thermal mass in its most general term describes the ability of the material to store heat. This means that the materials can absorb, store and release heat (at a later time) to maintain a thermal comfort inside a building. For a material to have good thermal mass, it needs to have –
• A high specific heat capacity – the heat squeezed into every kg is maximized.
• A high density – allows the material to store the maximum amount of heat.
• Moderate thermal conductivity – allows for heat to flow in and out of the material
slowly in accordance with the diurnal heating cycle.
Building materials like concrete, stones, and bricks have high specific heat capacity with moderate thermal conductivity, making them useful as thermal mass. 22
Thermal mass can thus help maintain thermal comfort both during summer and winter. During a summer day, the windows are kept shut and the projection helps minimize the solar gain. The temperature is maintained because thermal mass absorbs the heat. During a summer night, the windows are opened to provide cooling to the thermal mass and dissipate the heat to the outside.
Figure 33 Working of thermal mass during the summer
(Source: Thermal Mass For Housing, The Concrete Center, MPA pg 3)
22 MPA, The Concrete Center. Thermal Mass Explained. Thermal Mass: What it is and How it is used. Surrey, 2009.
33
During a winter day, sunlight strikes the thermal mass which heats the air and the thermal mass, the sunlight helps keep the room warm. After the sun sets on a winter night, and with the windows shut, the thermal mass releases heat slowly which helps maintain the thermal comfort inside the room. Thermal mass can thus be a great asset for heating and cooling buildings.
Figure 34 Working of Thermal Mass during the Winter
(Source: Thermal Mass for Housing, The Concrete Center, MPA pg 3)
Because both vernacular buildings and the RCC constructions utilizes bricks, both styles of constructions benefit from the use of thermal mass. The vernacular buildings have thicker walls and higher storage capacity in comparison to RCC buildings. The concrete floors and frame in the
RCC building also contribute to the thermal mass, however, the concrete floors are usually insulated with carpets, blocking direct gain, which prevents the thermal mass from being fully realized.
Another feature that helps control the internal temperature in a vernacular building is the placement of floors and windows. The use of ground floor as shop and storage ensures the living quarters above is insulated from the cold that emanates from the ground in winter. And in a similar fashion, the placement of the kitchen on the top floor keeps the living area from overheating in summer.
For extra heating requirements, a traditional housing uses charcoal brazier to heat occupied rooms
34 in winter. The overhanging roof allows low sunlight through to keep the interior warm during winter but protects the walls from overheating in summer.
Overheating
Controlled Internal Temperature
Cooler
Figure 36 Left: The spatial arrangement aiding the internal temperature control, Right: Flow of breeze through the vernacular building aiding in cooling the building.
(Source: author) On the other hand, the lack of adequate projections shielding the openings could reverse the effect and cause overheating in the buildings during summer. The flat roof in an RCC building doesn’t help with the hot summer either as heat from the roof transmits to rooms below raising the temperature and causing the living area to overheat during summer. In winter, Figure 35 Overheating on the top floors in summer.
(Source: author)
35 additional heating in an RCC building is usually provided by electric or gas heaters.
In both cases, windows play an important role in regulating the internal temperature, with the added help of electrical fans, window unit ACs and heaters to aid during summer and winter respectively.
36
5. Seismic Resilience
An earthquake, as the name suggests, is movement of the earth that causes the ground to shake.
According to plate tectonic theory, the earth consists of a viscous, molten magma mantle with several lower-density rock plates floating on it. These plates move causing cracks where the plates move apart, and fault zones where they move into each other or slide adjacent to each other. These moves create compression and shear stress in the plates. When the energy built reaches its threshold, the energy is dissipated causing an earthquake. Three main types of stress waves are released during an earthquake: compression waves, shear waves, and surface waves – each of which is at different speeds. As a result, different ground motions are experienced in different places with different soil conditions.23
The intensity of the earthquake is measured using the Richter scale - it provides the magnitude of the earthquake by reading the seismograph oscillations. The Richter scale is a logarithmic scale, and each increase in measurement indicates a magnitude amplification of tenfold. Usually, the more destructive earthquakes measure at least a 5 on the Richter scale.24 Depending on the vulnerability and frequency of the area to undergo an earthquake, the world has been divided into seismic zones - where a seismic zone I is a zone that is least prone to earthquakes, and a zone V is most prone to earthquakes; Nepal is in Zone V.
As movements of the ground during an earthquake is unpredictable, there is no certain way to make a building a hundred percent earthquake proof. The ground movements damage the buildings
23 Wight, James K., MacGregor, James G., Reinforced Concrete Mechanics & Design. New Jersey: Pearson Education Inc., 2012.
24 AIA/ACSA Council on Architectural Research. Buildings at Risk: Seismic Resistant Design Basics for Practicing Architects. Washington, 1992.
37 by generating inertial forces caused by the vibration of the buildings’ mass. Some of the causes of failure in a building are:
1. Elevation (Vertical) Structural Irregularities
a. Stiffness irregularity or a soft story.
b. Weight (mass) irregularity.
c. Vertical geometric irregularity.
d. In-plane discontinuity in vertical lateral force.
e. Discontinuity in capacity or a weak story.
2. Plan (Horizontal) Structural Irregularities
a. Torsional irregularity - these need to be considered when the diaphragms are rigid.
b. Re-entrant corners.
c. Diaphragm discontinuity.
d. Out-of-plane offsets.
e. Non-parallel systems.25
There are however ways that can be used to make a building resist an earthquake better. These techniques are used to help the building retain its structure better and avoid total collapse of the structure. The primary considerations are developing a smooth continuous load path through the building and avoiding mass and configuration irregularities. Some of the techniques that can be adapted to achieve this are:
1. Use of Regular configuration.
2. Introduction of shear walls.
25 Ibid.
38
3. Introduction of seismic joints separation.
4. Tying buildings together stronger to avoid deflection.
5. Providing a stiffer free end for the building.
6. Avoiding re-entrant corners or having them tied together stronger.
7. Using splayed corners over a right-angle corner.26
5.1.History of Earthquakes in Nepal
Nepal was formed by the Indian plate crashing into the Eurasian plate. The Indian plate still exerts pressure into the Eurasian plate; the exertion causes massive accumulation of stress at and around the fault area. When the stress exceeds the threshold, energy is released in the form of slip causing the ground to shake.
Nepal has therefore gone under many earthquakes over the centuries. Large earthquakes have occurred in 1253, 1407, 1681, 1803, 1824, 1833, 1835, 1934, 1988 and the most recent one in
2015. The earthquake on 25th April 2015 registered as 7.8 on the Richter scale, and a second earthquake on 12th May 2015 registered as 7.3 on the Richter scale.27
Because earthquake has been a reoccurring phenomenon in the country, the architecture, both traditional and the contemporary, has been constructed and adapted keeping in mind the seismic vulnerabilities. Nevertheless, no building is ever fully earthquake resistant, there are some flaws that are prevalent in both styles of architecture.
26 Ibid. 27 Stoppelaar, A. O., Oosterhof, A. J., Can Düzgün, B.C., Spelt, C.J., van Wijnbergen, E.C.M. Shock Safe Nepal. Delft University of Technology. Netherlands, 2015
39
Some of the characteristics of both kinds of architecture that make them seismically resilient and vulnerable are as below:
5.2.Vernacular Architecture – Seismic
The various earthquake-resistant technologies can be observed in the vernacular architecture of
Kathmandu Valley are:
1. Building configuration
A Newari building is usually rectangular in plan and
symmetrical in elevation. This reduces eccentricity i.e.
helps minimize, and at best even eliminate, the distance
between the center of mass and the center of resistance,
which minimizes possible rotation and distortion, and
minimizes the damages to the building that would
Figure 37 Center of Mass coincides otherwise occur due to torsion. The uniform story with Center of Resistance
(Source: author)
Figure 38 Symmetrical Elevation of the vernacular architecture
(Source: https://samirpathak.myportfolio.com/kirtipur-nepal)
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height of also contributes to equal stiffness of the walls which prevents irregularity of
stiffness and thus prevents stress concentrations.
2. Building Materials
A Newari building is built using brick, timber, and stones. They are not only used to
construct a timber frame in the interior but is also used in many other components like
beams, joists, lintels, doors, and windows. These wooden members help tie the brick walls
and prevents the walls from distortion and displacement when the lateral forces are exerted
in the building. Bricks are a good material to handle compression, but it fails in shear.
Timber on the other hand has the capability to withstand both tensile and compressive
stresses, including shear.
Timber can absorb the forces
and themselves distort,
without breaking apart, which
can prevent a sudden collapse
of the walls.
The brick walls of a vernacular
building are tapered as it
moves upwards, with the upper
floor constructed with timber Figure 39 Section showing all the wooden elements in the vernacular building. frames, making the structure (Source: author) lighter at the top.
41
Figure 40 Isometric view of the roof and the pillars that use timber in the vernacular building
(Source: Gutschow, Niels. Newar Towns and Buildings. pg 159)
3. Openings
Except the large window on the second
floor, the openings in a Newari building
is typically minimal in size and number,
and always placed symmetrically. The
double framed doors and windows Figure 41 Double frame windows of the Newari usually run from the outer façade into Architecture
the inner, acting as a tying unit between (Source: Gutschow, Niels. Newar Towns and Buildings. pg 158) the various layers of bricks that form the wall.
Similarly, there are various shortcomings in a vernacular building that can be strengthened to make the vernacular architecture more earthquake resistant. Some of these shortcomings are:
42
1. Soft and weak story
The timber arcades on the ground floor weaken the stiffness of the structure and create a
Figure 43 Section of Newari Vernacular Building showing the soft story
(Source: author)
soft story. The timber structures on the
upper floor also change the stiffness of the
structure and make it weaker at the top.
While making the structure lighter at the
top is beneficial, it makes the stiff
elements (masonry) more susceptible to Figure 42 Open Front of a vernacular building creating stress. Thus, the lateral forces during an torsion due to unequal perimeter stiffness
(Source: author) earthquake will be distributed unevenly
43
causing stiffer members to bear most of the load, making them vulnerable and susceptible
to buckling. This can also lead to the entire structure collapsing.
2. Vertical Plane Irregularity/ Discontinuity
The placement of large windows on the third floor means there is a huge gap in the wall.
This not only affects the load path, but it also affects the perimeter stiffness because the
structure will be weaker at the opening. Care must be taken to ensure that the wooden
window has adequate rigidity to help maintain the overall stiffness of the perimeter.
3. Vertical Mass Irregularity
The roof is a critical part of the
structure because it makes the
structure top heavy. The extra heavy
roof creates a weak story effect on
the floor below which can buckle
and fail when the lateral forces are
applied during an earthquake. Also
critical is the large bay window that
creates mass irregularity and causes
Figure 44 Section of a vernacular house showing the vertical mass vertical acceleration. irregularity (Source: author)
4. Weak floors
The traditional mud or clay floors have no tensile or shear capacity and fail to act as a
diaphragm. This creates a lack of stiffness in the structure as the floor isn’t rigid.
44
5. Weak corners
The cross walls are often built with little to no interlocking, this creates weak corners that
cannot withstand the movement of an earthquake. This can result in the separation of the
walls, and ultimately the collapse of the walls and even the building during ground shaking.
Figure 45 Weak corners resulting in cracks and collapse of buildings
(Source: https://i1.wp.com/www.circleofblue.org/wp-content/uploads/2015/05/NepalBuilding- 1.jpg?fit=1000%2C667&ssl=1) Besides the techniques for better performances of a building, it is also important to care for and maintain the buildings. As vernacular architecture is often built with materials that are organic, they tend to deteriorate faster than the newer engineered products, but this also means that the building materials are more easily and readily available than the engineered ones are.
It is interesting to note that there are various festivals celebrated by the Newari people of
Kathmandu Valley that incorporate the maintenance and upkeep of house into the festival. During the festival of Laxmi Puja28 in Tihar29, people are encouraged to coat their floors with clay (and sometimes even cow dung mixed with clay) as an auspicious gesture to welcome the goddess
28 Laxmi Puja is a festival celebrated on the 3rd day of one of Nepal’s biggest festival Tihar. 29 Tihar is a big Hindu festival celebrated around October – November. The festival spans for 5 days and entails worshipping cows, dogs, crows, the goddess Laxmi, your own soul, and your brothers.
45
Laxmi30 into the house; this practice is not only religious, it also inadvertently promotes the upkeep and maintenance of a house.
5.3.RCC Structure - Seismic
The RCC structures if built with appropriate design and workmanship will mathematically have better chance to withstand the forces of an earthquake than the vernacular buildings. Some of the other attributes that make an RCC structure more earthquake resistant are:
1. Use of Steel and Cement Concrete to create the moment resisting frame
The use of steel reinforcement bars makes the RCC structure ductile. Steel has a very high
elastic coefficient and a long plastic
plateau, which makes it a very
ductile material. Therefore, when
subjected to extreme loading during
an earthquake, the steel may deform
yet continue to carry the load of the
structure, ensuring a total collapse
Figure 46 Image showing the construction of RCC building does not occur. If it does, there is (Source: https://www.microaidinternational.org/single- plenty of time for the occupants to post/2016/06/02/Nepal-House-Project)
escape.
Cement Concrete on the other hand not only gives strength to the structure, but it is also
heavy and very useful in damping the amplitude of the vibration of the earthquake. This
30 Goddess Laxmi is the goddess of wealth and purity and is typically worshipped to gain prosperity and financial advantages.
46
helps in minimizing the effect of the earthquake on the building by reducing, and in rare
cases even neutralizing, the vibrations of the earthquake.31
2. Equal Floor Height
When an RCC structure is built
with equal floor heights, and
phenomenon such as short
columns are avoided, the
stiffness of the structure remains Figure 47 Building's reaction to earthquake force with uniform uniform throughout the building. stiffness and different stiffness (Source: FEMA Risk Management Series) This ensures that stress during
the earthquake is distributed equally and acts upon the building equally as well which
eliminates the chances of a building being stressed at the stiff areas and prevents buckling.
3. Uniform Mass Distribution
Unlike vernacular buildings, RCC buildings do not have a heavy top. The roof which is
basically a horizontal diaphragm, acts as an element that works in distributing the lateral
forces from an earthquake to the beams and the columns.
However, there are many things that can go wrong in an RCC structure if it is not designed and constructed properly leading to their failure. Some of the design flaws are:
31 This can lower the risk of total collapse as more damage occurs through continuous oscillation than through a higher acceleration for a short amount of time.
47
1. Short Column Effect
A short column effect arises if the walls aren’t constructed from the base to the top of a
column – this phenomenon affects the stiffness of the column and can cause uneven stress
concentration and bending failure.
2. Soft Story
Use of open ground floor either for a garage or for a rented space creates an irregularity in
the overall stiffness of the outer façade, which can lead to uneven load and stress
distribution and can result in the floor buckling and even the collapse of a building.
Figure 48 Buckling caused by soft story
(Source: http://archive.nepalitimes.com/article/nation/photos-nepal-earthquake-2015,2207, https://www.verrassendviltwerk.nl/images/foto-nepalreis/twee/nepal3.jpg) 3. Plan and Façade Irregularity
Because of the flexibility that a moment resisting frame provides in the plan and form of a
building, architects and clients come up with irregular floor plans that can be problematic
during an earthquake. The irregularity in plan and elevation can shift the center of
resistance away from the center of mass leading to overturning and torsion in a building.
Irregular plans also create reentrant corners which cause stress concentration at the corners
48
making it vulnerable during an earthquake. Similarly, the vertical irregularity like
cantilever can disrupt the load path which is essential for the load to be transmitted to the
ground and can cause vertical acceleration resulting in overturning.
Figure 49 Examples of vertical and plan irregularity in the RCC buildings
(Source left to right: Shock Safe Nepal, gharjagga.com) 4. Pounding Effect
Buildings of different heights oscillate at different frequency, and when they don’t have
enough space between them, can hit each other causing a pounding effect. This pounding
can cause enough damage to discontinue the load path or create irregular stiffness (by
weakening or destroying vertical surfaces and columns) which can lead to overturn or
collapse of a building.
5. Uneven Story Height
Like the soft story effect, buildings with uneven story height can also result in unequal
stiffness, resulting in stress concentration and buckling during an earthquake.
49
Figure 50 Weak story induced by uneven story height.
(Source: author) 6. The practice of placing water tank at the top
The lack of infrastructure in Nepal has led to people placing huge water tanks at the top of
a house to store water. Again, this disbalances the mass distribution of the structure causing
mass irregularity which can lead to overturning and collapse of a building.
Figure 51 Placement of Water Tanks on the rooftop
(Source: http://pilot-projects.org/images/blog/IMG_4514.jpg, www.gharjagga.com.)
50
5.4. Implication
By observing both the vernacular architecture and the RCC structures, it can be deduced that both the plan and the elevation of a building should be symmetric to reduce eccentricity in every direction and avoid overturning due to torsion.
The buildings should have a low height to width ratio, and a compact plan with low length to width ratio to minimize the tendency to overturn.
The number of openings should be less, and carefully and symmetrically placed with properly reinforced frames to make them less seismically vulnerable.
Ductile materials should be given preference with the highest preference given to timber and steel because of their ability to withstand tensile strength.
Thus, both the vernacular buildings and RCC constructions have elements and techniques that make it more seismically resistant and vulnerable. The lessons from both kinds of architecture can be used to strengthen the other.
5.4.1. Ways to strengthen the vernacular architecture
The vernacular architecture can benefit from the new construction method through:
1. Modification of overall behavior of the structure
This can be done through stiffening the structure by adding shear walls or braced frames.
In a vernacular structure the mass irregularity is evident, as can be observed from the
section. The irregularity will increase deformation as stress concentration at weaker stories
are more likely to occur when the lateral forces are exerted to a structure. This problem can
be lessened when the weaker stories are stiffened by adding braces that increase the
51
stiffness to match, as closely as possible, the stiffness of other stories, thus balancing the
overall stiffness of the structure.
Figure 52 Addition of braces on the soft story to increase the stiffness.
(Source: author) 2. Strengthening the weak corners and overall strength of the wall
The weak corners can be strengthened by interlocking the corners better. This can be done
by introducing timber reinforcements along the wall of the structure which helps lock the
corners and make them more rigid and less susceptible to ground acceleration.
Figure 53 Right: Bracing the corners to strengthen them.
(Source: author)
52
Figure 54 Different Methods of reinforcing the corners
(Source: Investigation of Damage in and Around Kathmandu Valley Related to the 2015 Gorkha, Nepal Earthquake and Beyond)
3. Ensuring the strength of mud mortar
Assuring that the load path is always complete, and a structure can perform according to
the designer’s assumption is crucial to maximize seismic resilience. This means the walls
need to be sturdy and able to withstand the ground acceleration without crumbling. The
strength of the walls can be increased by increasing the strength of mud mortar. For a strong
mud mortar, black clay mud should be avoided. The mortar can also be strengthened by
using cow dung.32 An addition of 10% cement to the mixture can also provide enough
strength.
32 Pant, Shaswant, Newari architecture in Kathmandu: ‘Old and weak’ buildings are also part of heritage. (http://english.onlinekhabar.com/newari-architecture-in-kathmandu-old-and-weak-buildings-are-also-part-of- heritage.html)
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5.4.2. Ways to strengthen RCC construction
In a similar manner, an RCC construction can borrow some attributes from the vernacular architecture:
1. Regular configuration
The strict adherence to the symmetrical and regular configuration (preferably 2:1 but not
more than 4:1 length to width ratio) of the vernacular architecture helps ensure the building
has equal resistance from overturning in every direction. This strategy can be implemented
on an RCC structure as well, if a building cannot be symmetrical, it can have a balanced
asymmetry and an equal mass distribution throughout the structure.
2. Equal Mass Distribution
The heavy roof in the vernacular building causes the structure to be heavier during the
earthquake. Therefore, an RCC building should prevent this unequal mass distribution
which can prevent a weak story and prevent buckling under the earthquake stress.
3. Height Restriction
The floor height and the building
height of the vernacular
architecture are limited to avoid
disproportionately tall buildings
which can cause vertical
acceleration and overturning. Figure 55 Slender Buildings in Kathmandu
(Source https://www.flickr.com/photos/ivo1/15825961983)
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6. Conclusion
One of the many paradoxes that challenge the developing world in its advent of modernization is the balance it needs to find between the old world and the new. How far from one’s root can one wander to step into the modern world without straying too far? Or in other words, how do you stay rooted but still move forward?
In the present day, where the world is so intently moving towards globalization and universalization it isn’t surprising that many cultures are sometimes lost in the whirlwind. While moving ahead and changing according to the need of time is a necessary thing, neglecting culture along the way is not always ideal. Hence, globalization has had both a positive and negative effect on the world, especially the developing ones. As Paul Ricoeur states in History and Truth,
The phenomenon of universalization, while being an advancement of mankind, at the same
time constitutes a sort of subtle destruction, not only of traditional cultures, which might
not be an irreparable wrong, but also of what I shall call for the time being the creative
nucleus of great cultures, that nucleus on the basis of which we interpret life, what I shall
call in advance the ethical and mythical nucleus of mankind… Thus, we come to the crucial
problem confronting nations just rising from underdevelopment. In order to get on to the
road toward modernization, it is necessary to jettison the old cultural past which has been
the raison d’etre of a nation... Thence the paradox: on the one hand, it has to root itself in
the soil of its past, forge a national spirit, and unfurl this spiritual and cultural
revindication before the colonialist’s personality.33
33Ricouer, P. History and Truth. Evanston: Northwestern University Press. 1965. Pg 287
55
He highlights the contradiction and the conflict that is arising in the developing world as it struggles to keep up with the developed world. While this conflict plagues all parts of society and culture, the most prominent witness of this conflict is perhaps the architecture, as it is the most physical and notable manifestation and reflection of the society.
The vernacular architecture of any place is the bearer of traditions and culture that have been passed down from generation to generation. They hold not only the ancient building traditions but also showcase the local materials and the lifestyle of the people to whom they belong. And although they were built without the supervision of any architects, they have evolved through trial and error over a vast span of time and have almost been perfected. They have thus borne witness to evolution and history throughout the years, making them not only very symbolic but also an ardent display of culture and tradition.
The high rise and the concrete buildings, on the other hand, are the prospects of the modern world
– it is a milestone of the advancement of human knowledge and technology. It is also sometimes a marker of the society and the developing country stepping into the developed world and standing equal with them.
As we advance and become more knowledgeable, we are now more than ever, able to manipulate the environment around us according to our need. Therefore, today, the limitations of climate or materials that once guided a building and its construction are no longer as grave an issue as it used to be. The advancement of technology has enabled building materials to now be transported thousands of miles, and the climate response of a building be tailored accordingly. This has truly paved the way for an anonymous building culture that can be constructed anywhere in the world
56 which can, without meaning to, lead to buildings often being isolating from their surrounding and maybe even their culture.
The same struggle is prevalent in Kathmandu, where the architecture is currently transitioning in its attempt to accommodate both the new and the old. Care must therefore be taken if we are to preserve the old building culture and let it persevere on to the future. Turning a blind eye to them might result in a future where the old building culture and old buildings no longer exist.
Preservation of historical buildings and values thus becomes very important. The threat of an earthquake and seismic resilience are therefore not the only reasons behind the flurry of new RCC construction. The building culture is also rooted in the desire for people to want to be modern and comfortable.
The preservation of the vernacular could be done in variety of ways, and while visual elements and aesthetic characters of any architectural style is the first thing that seems to get priority, it is not the only element or the most important one that can be transferred and passed on. Kenneth
Frampton writes in “Towards a Critical Regionalism: Six Points for an Architecture of
Resistance”,
The tactile resilience of the place-form and the capacity of the body to read the environment
in terms other than those of sight alone suggest a potential strategy for resisting the
domination of universal technology. It is symptomatic of the priority given to sight that we
find it necessary to remind ourselves that the tactile is an important dimension in the
perception of built form. One has in mind a wide range of complementary sensory
perceptions which are registered by the labile body : the intensity of light, darkness, heat
and cold; the feeling of humidity; the aroma of material; the almost palpable presence of
57
masonry as the body senses its own confinement; the momentum of an induced gait and the
relative inertia of the body as it traverses the floor; the echoing resonance of our own
footfall … Critical regionalism seeks to complement our normative visual experience by
readdressing the tactile range of human perceptions. In so doing it endeavors to balance
the priority accorded to the image and to counter the Western tendency to interpret the
environment in exclusively perspectival terms.34
He puts as much importance on other sensory perceptions as he does on the visual elements of a built form. Therefore, as we move forward, there are ways in which we can continue the vernacular tradition by incorporating the tactile along with the visual. Some of the elements of the vernacular architecture has unwittingly transformed and continued in the newer construction, while others have been forgotten completely.
As people develop and become modern, it is natural to want to move ahead and modernize buildings and the living environment. However, care must be taken to not eliminate the old either.
The old can be carried along and passed on, if not through exact duplication, then in its essence.
As the domestic architecture has developed and morphed over the years, the traditional architecture of Kathmandu Valley has seen drastic changes in the way it looks and is constructed. With the new construction rapidly replacing the older one, the vernacular architecture is at the brink of disappearing from the urban fabric.
34 Frampton, Kenneth. Towards a Critical Regionalism: Six points for an architecture of resistance. pg 28, 29
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It is also not ideal to abandon the RCC altogether and return to the vernacular architecture as well.
The two types of architecture both have their advantages and disadvantages as discussed in table
1 and table 2.35
The old and the new therefore needs to come together to realize an architecture that is reliable, resilient and reflective. Some of the ways in which the two can be furthered into the future are by preserving the vernacular architecture wherever they can be preserved, and where they cannot be preserved, the vernacular can continue in its essence through the RCC architecture in a hybrid way.
The hybrid of the vernacular and the RCC could be carried out through either one or a combination of continuation or adaption of the seismic resistance abilities, building materials, thermal elements, social interactions, aesthetics elements, and spatial arrangement.
1. Seismic Resistance
The earthquake has always been a huge part of Nepal, its people, and the building culture.
Regardless of the style of construction, the changes in construction methods and the change in lifestyle, the one thing that has remained constant through the history of building culture in
Kathmandu has been the need to construct buildings that are seismically resistant. The need for the earthquake resistant buildings is, therefore, a primary force that guides all constructions in
Nepal.
As previously discussed, vernacular architecture and RCC constructions both have their assets and liabilities when it comes to their seismic resilience. The two of them can always learn from each
35 Refer Appendix
59 other and strengthen each other to further promulgate themselves. Vernacular can take lessons on the load path, stiffness and overall performance of buildings during an earthquake, while RCC buildings can borrow elements of ideal configuration from vernacular architecture.
Hybrid construction can thus take lessons from vernacular by adhering to symmetrical elevation, regular floor plan, bands in masonry to increase stiffness, a lighter top to avoid vertical acceleration while using the RCC moment resisting frame to ensure maximum protection against earthquakes in the future.
Figure 56 An RCC construction that is built with RCC frame and masonry infill, with symmetrical in elevation, regular plan, and bands
(Source: https://www.microaidinternational.org/single-post/2016/06/02/Nepal-House-Project
2. Building Materials
While form and aesthetic elements of a building contributes a lot towards the identity and character of a building, building materials are an equally important aspect of the identity. Brick and wood are two very prominent building materials that are used for the construction of traditional buildings. The earthy colors of brick and wood have given the vernacular architecture its harmony and uniformity.
60
Hybrid construction can utilize these aspects by using materials like brick and wood wherever possible. This not only makes the building environment-friendly but also provides harmony and uniformity that the current rainbow-colored building trends lack. They can also be treated with weather-resistant treatments to ensure the longevity of the structure. The traditional roof that is constructed using heavy clay tiles can be constructed with lighter materials to keep them from being counterintuitive to the seismic forces. In reverse, the details of the frame can be changed to withstand more load to counter the weight of the sloped roof.
The uniform sloped roof can contribute to the harmony of the existing architecture by not conflicting with the already existing vernacular architecture that has sloped roofs but can also work well to maximize the thermal mass and help with water runoff and surface wall protection during the monsoon season.
3. Thermal Resistance
Heavyweight construction materials like brick, stone, and concrete are ideal materials to use for thermal mass as they have high storage capacity with moderate thermal conductivity. Because vernacular architecture has a higher thermal capacity, due to the spatial arrangement and thicker thermal mass, the thermal comfort is, therefore, a key character of the vernacular architecture.
Although thermal mass is present, the same thermal comfort is not achieved in an RCC construction, the thermal comfort of an RCC structure largely relies on mechanical methods to maintain the thermal comfort inside a building.
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Thus, instead of treating the brick walls in hybrid construction as just an outer shell and partitions, the thickness of the brick walls can be increased, and the thermal capacity of hybrid buildings be increased. The spatial arrangement of the buildings can also be rearranged to prioritize maximum thermal comfort for the living spaces and sleeping spaces.
4. Social Interaction
The open store front, shared courtyard and projecting bay window in the vernacular architecture have all been a crucial part of encouraging interactions of the inhabitants with the surrounding.
The same level of religious and social interaction does not occur in new buildings anymore. The loss of courtyards has been crucial to the loss of social interaction, but all is not lost as the terraces have emerged as the new place of social interactions and daily activities.
Thus, if possible, hybrid houses should be built around courtyards, however as land is scarce and open courtyards might not be possible now, terraces should remain in hybrid constructions to ensure that there is a space for social activities to continue. The placement of terrace, however, conflicts with the Figure 57 Sloped roof with cut out for terrace space sloped roof, a middle ground in which both could (Source: author) be incorporated is through sloped roofs with cutouts for terraces. This can ensure that the benefits and the architectural characteristics of the sloped roof are maintained while incorporating the terrace space from the RCC construction.
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5. Aesthetic elements
The most easily distinguishable and defining character of vernacular architecture is the physical characteristics of the structure. The long-standing buildings that remain today have great historical value and carry the important task of maintaining and promulgating the cultural and architectural identity. It is important to preserve the old not only for those values but also because they are a huge part of tourism – which is responsible for a significant portion of the country’s economy.
Therefore, all vernacular buildings that can be preserved should be preserved, and people made aware of the need to take care and maintain the historic buildings.
For the buildings that are destroyed, the various building components like the intricate doors and windows may be reused in the reconstruction of the buildings. Wherever possible, the vernacular architecture should be rebuilt and preserved in its traditional form – at least in the city core where the world heritage sites are situated and, in the outskirts, where tourists flock to witness the traditional architecture. Reconstruction in vernacular style should be promoted in areas outside of the world heritage sites wherever possible.
For the buildings that will be reconstructed in the newer construction style, copying the elements of vernacular architecture onto the modern could make it look like a vernacular building, but it would just be a reproduction of the old, and an empty shell of the past. Instead, aesthetic characters that are reminiscent of the vernacular but not necessarily a deliberate copy can be carried on by hybrid constructions through the implementation of symmetrical elevation, sloped roof, regular floor plan, courtyard settlement.
63
Figure 58 New Construction adapting the vernacular architecture and its principles.
(Source: Left: https://aees.org.au/nepal-earthquake-photos/tony-hagen-house-one-of-first-bldgs-in-nepal-minor-damage-from- outside/, Right: https://foursquare.com/v/vajra-guest-house--restaurant/517f4f4fe4b019ff231f9a23/photos)
6. Spatial Arrangement
The vertical arrangement of a vernacular house is one of its distinctive features and something that sets it apart. The definite formula of having the spaces planned and arranged in a certain way was followed by everyone. This has, however, changed with modern constructions as houses expanded horizontally rather than vertically.
In Kathmandu, where land is scarce today, the only alternative to accommodating the large influx of people and to have open spaces is to build vertically. The vertical spatial arrangement may be adapted to maximize the use of the plot and carry on the traditions of vernacular division of spaces and thermal advantages that follow. However, as people have modernized so have their requirements for a dwelling. The traditional architecture does not have space for garages, dining rooms or guest rooms. These are all modern requirements that vernacular architecture does not
64 accommodate. An RCC construction, on the other hand, has a flexible spatial layout that can accommodate the modern requirements as it does not necessarily adhere to any of the vernacular rules. Hybrid constructions can have flexible spatial layout according to the requirements, which ensures the comfort and necessities of the modern life, but it can borrow from the vernacular by segregating the private and the public spaces.
Therefore, as Nepal urbanizes, the lifestyle of people will advance with it and so will the architecture. To make sure that vernacular architecture persists but does not hinder the advancement and evolution of the contemporary building culture, vernacular architecture and RCC structures can mix together to form a hybrid architecture that takes advantage of both the architecture styles and ensures their continuity into the future. The integration of these two systems is ultimately a design project – one that cannot be addressed within the scope of a written thesis.
The purpose of this thesis is to lay out the salient issues that bear on the problem for future designers.
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Appendix
Comparison of the advantages and disadvantages of the traditional and new architecture of
Kathmandu.
Table 1 Advantages and Disadvantages of Vernacular Architecture
Advantages Disadvantages Lifestyle • Reflected the lifestyle of the • Indicative of the past and the farmers and tradesmen who were undeveloped Kathmandu. natives of Kathmandu Valley. • Could be perceived as a hindrance • Encouraged social and religious to progress and development. interaction with the open ground floor and large bay windows. Building • The use of wood, brick, clay, and • While building with the natural Material stones meant that the building material is more environmentally materials are easily available from friendly, they tend to deteriorate the surrounding and cost-efficient. quicker • The use of natural materials made • Exposed bricks without any it more environmentally friendly. weather protectant erode away • The craft of building and wood over time. craftsmanship is kept alive by • The workmanship required for the constructing them in the building. construction of the vernacular • With proper maintenance, these building is disappearing making buildings have stood for two to the construction costlier. three hundred years. • Chances of a fire hazard. • High maintenance cost. • Child labor approaching slave conditions in the local brick kilns. Visual • Tied to historical values and • Reminiscent of the past which Elements/ associated with the national might not be what everybody is Aesthetics identity. looking for.
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• The use of bricks, stones, wood, • Could be outdated and not and clay gives the vernacular reflective of the current time. buildings an earthy and warm • Vernacular architecture might not tone, which is in symbiosis with be as flexible in its design and the surrounding and gives the space as the RCC construction buildings uniformity and might be. harmony. • The sloped roof is reminiscent of the mountains and responsible for weather insulation. • Large carved wooden windows reflect the craftsmanship of the Newari community. Thermal • The thick walls ensure a larger • The thickness of the wall that is Properties thermal mass which ensures better helpful in maintaining the thermal thermal insulation. mass also means that more brick • The wooden lattice windows is required increasing the cost of provide ventilation and easy wind the building. flow. • The wooden windows are more • Sloped Roof provides a variety of expensive than the alternative thermal and weather insulation. aluminum windows. The roof helps in an easy run off • The lattice windows while good the water. It also helps protect the for ventilation isn’t the most ideal wall of the buildings from being for lighting. subjected to the harsh rain. The sloped roof also shades the building wall from harsh summer sun and helps keep the interior cool.
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Seismic • Use of regular plan ensures that • Thick walls have an adverse Properties the building does not get effect on the seismic resistance eccentrically loaded during an capability as the structure earthquake. This makes sure that becomes heavy and increases the the building doesn’t turn over chance of buckling. • Use of timber elements in the • The overhanging roof constructed façade and the structure of the using clay tiles makes the building helps dampen the effect structure counterintuitive as it of the earthquake as timber can makes the structure top heavy and withstand high loads for a short thus susceptible to damages time and retain its elasticity and during an earthquake because of strength. vertical acceleration. • Low story height helps the • The large openings in the upper vernacular building maintain its façade of the building with the stiffness and better tackle the use of overhanging bay windows lateral earthquake forces. cause irregularity in the vertical • Smaller windows made from plane which weakens the timber help keep the perforation structure’s performance during an in the façade to the minimum earthquake. which helps in maintaining the • Unreinforced masonry, stiffness of the wall. Windows are particularly with weak mortar, made from wood, which makes have centuries-old history of them ductile and more hospitable seismic failure. to the shear forces. Social • Courtyard – used for various • Lattice windows keep the interior Interaction social activities and religious private and hinder connection festivals. with the outside world. • The bay windows help connect • The rigidity of structure limits the the people in the house to the ability to alter spaces or add modern amenities.
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processions and the festivities going on in the street below. • The workshop and shops on the lower floor create a connection between the street and the building. Climatic • Roof overhangs shield from rain • The exposed bricks can erode and Features and harsh sun. It also helps the hinder the strength of the structure thermal mass control the internal over the course of time. temperature. • Effervescence can cause patchy • Thermal mass for maintaining a and aesthetically unpleasing comfortable internal temperature. facades. • Windows and courtyard planning • The clay tiles in the roof need allow adequate ventilation. frequent maintenance and repair over time.
Table 2 Advantages and Disadvantages of RCC construction
Advantages Disadvantages
Lifestyle • Reflects the modern society today • Although many families live where a good majority of the under the same roof, they do not population has migrated to the city necessarily interact with each and works in a technical and/or a other. professional job. • No open ground floor that • Multiple unit houses to encourages interaction of the accommodate the increasing inhabitants with the surrounding. population in the city Building • RCC moment resisting frame • Not very environmentally
Material makes the structure earthquake friendly as the materials take a resistant. long time to deteriorate.
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• The selection of the material and • The materials required for the structure ensures longevity and MRF and its construction is durability. expensive. • Low Maintenance of the structure. • The construction requires skilled • More fire resistant. labor and equipment. • Although initial construction cost • More material from non-local is high, the overall lifetime cost of sources requiring high carbon the structure might be balanced expanse transportation. through the longevity of the structure. Visual • The façade can be painted any • The flexibility of the design also
Elements color giving the owner more means that there is no uniformity control over their house and its in the buildings. aesthetic appearance. • Stratification of people based on • The modern design elements give the design and the façade of the the building a new look that house – a class stratification. appeals to occupants’ sense of • upward mobility. • The new look also gives the flexibility of not having to conform to a certain design or style. Thermal • The brick walls ensure that the • Not as much thermal mass as the thermal mass can be used to vernacular architecture. absorb, store and dissipate heat to • Flat roof causes over-heating of maintain thermal comfort inside the top floors. the building. • Open and bigger windows for better airflow.
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• Use of overhangs protects against the harsh summer sun. Seismic • Moment Resisting Frame helps • Irregular plan and reentrant resist both the compressive and corners can cause mass tensile stress during an earthquake. irregularity and torsional • Uniform mass distribution overturning. throughout the building ensures no • Open ground floor used for shop vertical acceleration. causes irregularity in stiffness • Major design codes account for which leads to soft story effect. much higher seismic resistance • Concrete structures tend to be than vernacular. heavier than wood leading to more seismic base shear. Social • There might be more interaction in • Stratification of people based on
Interaction houses that are rented out where the building façade and finishes. multiple families live. • The terrace has replaced the • The balcony acts as a place for courtyard, where neighbors social gathering and social would perform daily activities as interaction. a group, now perform them isolated. Climatic • The finish coat of paint can be • A flat roof can cause pooling of weather and termite proof. water in the roof. • The houses with projections are • Flat roof without projections can protected against rain. leave the walls exposed and • External water runoff drainage can susceptible to water during be planned. monsoon rain. This can also cause overheating of the thermal mass during summer.
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