Pathologies of Industrialized Buildings Made by Bearing Precast Concrete Panels. The Case Study of Intervention with the Same Building System at (27 dwellings), Francavilla in (27 dwellings) and (36 dwellings)

Filiberto Lembo 1

ABSTRACT

The research concerns some residential buildings, realized by 's IACP - Autonomous Institute for Popular Houses, by means of a call for bids made in 1984. Work begun the same year but, following the bankrupcy of the firm, occurred in 1986, it was necessary to re-assign it, and by doing so the work has been going on until 1991 for dwellings at Chiaromonte, 1995 for those at Francavilla and 1996 for those at Lagonegro.

Since the oneness of the system building in the three different locations, the interest of the research lies in the comparison between environmental features on one side, and on the other the state of preservation and pathologies who are there in the three interventions, with the aim of specifying how much these are connected with local environmental conditions, and how much on the contrary they follow on from defects of building systems of their's one, or from their use.

Since to date in many parts buidings are before made subjected to further retrofitting operations, with not completely satisfacting results, it is possible also to express some good practice criteria and workmanlike assessment in order to maintenance and thermal upgrade of this kind of buildings.

KEYWORDS

Durability & environmental exposition, Pathologies of envelope, Management mistakes, Design mistakes.

1 Faculty of Engineering of the University of (Department DAPIT), Potenza, , [email protected]

Filiberto Lembo

1 INTRODUCTION

The research, made in 2005-2006 thanks to the Master Thesis work of Eng. Adele Oliveto, coordinated by the writer, concerns some residential building of a public housing program, made by means of a call for bids of Potenza’s IACP – Autonomous Institute for Popular Houses - in 1984, originally designed to achieve 180 housing, but reduced to 90 due to problems of availability of land. The work begun the same year but, following the bankruptcy of the firm, occurred in 1986, it was necessary to re-assign it, and by doing so the work has been going on until 1991 for dwellings at Chiaromonte, 1995 for those at Francavilla and 1996 for those at Lagonegro.

The project was drawn up by the Firm successful undertaking of contract, the direction of the work was carried out by technical staff of IACP; for this reason it was possible a direct and continuous control on the quality of the project and works, in the course of their implementation. But such monitoring was not able to ensure good durability and the absence of diseases.

2 DESCRIPTION OF THE BUILDINGS

2.1 Typological characteristics

The 90 homes of three interventions in terms of types relate to a single model, which has three apartments to "windmill-type", around the staircase, repeated for a number of floors three to six. The coupling of two mirror image of the model determines unit buildings apparently different. The different size of housing, which are repeated across the column equal, does the rest (see Fig.1).

Figure 1. Plan of the basic model "windmill"(left) and specular double (right).

The orientation of housing is random, and the same blade mill basic model makes the housing environment (living rooms, bedrooms, kitchens and bathrooms) are pointing in all directions.

2.2 System Building

The building system, patented by successful undertaking of contract, the SACEP S.p.A., is called "S.B.S. System" and is characterized by large multitubular bearing precast panels, modular 120 cm, with the possibility of sub 30 cm, and this, for both floors, and walls, that are built on foundations made on site, with piles and continuous beams connection (see Fig.2a-b). The multitubular panels consist of two reinforced concrete walls R 30 with a thickness of 6.5 cm, connected to each other, each 60 cm, by 3.5 cm thick ribs to the panels of the facade, and 9 cm for those of floors. The cavities can be empty or (for facade panels) filled with high density polyurethane foam, thus achieving an average transmittance (according to the manufacturer) U = 0.64 W/m 2 K. Of course, on the two vertical edges, the need to connect the adjacent panels from the static point of view, they have each one vertical cavity of about 30 cm in length for the entire height of the panel, which is completely filled with concrete and reinforcement. It thus forms a thermal bridge 60 cm wide, all over the height of the panels, each time there are joints in line, in the corners to L, and T-junctions with internal bearing walls. A similar thermal bridge occurs horizontally, at the junction between the external chaining between bearing wall and floors. The joints between the panels forming the exterior walls

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are butt joint type, with silicone jointing compound (see Fig.2c).

Prefabricated structural components for the flights of stairs, cantilevering from the side panels, balcony railings and crown, complete the system. The roofs are sloping with fake cold ventilated roof with two slopes, with a slope of 8-10%, bitumen sheet coated, in Chiaromonte and Francavilla (see Fig.3), and of 30% in Lagonegro, covered with concrete tiles.

Figure 2. Precast panels for bearing walls and floors (a, b) and vertical joint between precast bearing panels for walls and floors (c).

Figure 3. Roof sections, Chiaromonte and Francavilla; typical (left), edge (right).

3 GEOGRAPHICAL AND CLIMATIC DATA OF THE THREE LOCATIONS

3.1 Geographical data

The municipalities of Lagonegro, Chiaromonte and Francavilla in Sinni are located in the inner part of the mountain of Basilicata, at a latitude between 40°7'29" and 40°4'56" and a longitude 15°46'6 " and 16°12'51". The heights above sea level of municipalities and of places of work are very different between them: they are in Lagonegro 772 m, in Chiaromonte 645 m and in Francavilla 355 m a.s.l.

The configuration of the planimetric and altimetric sites where there are the buildings is quite different: at Lagonegro the building is located at the top of the country, along the contours of a slope of 13%, and is oriented with the axis in the sense North-South (see Fig.5); in Chiaromonte buildings are located on the southeast side of the mountain, along the contours of a slope of 25%, and oriented in the direction southwest-northeast (see Fig.6); in Francavilla they are placed at the foot of the hill on which stands the town, north of it, on a slope of 12%, and oriented in the west-east direction (see Fig.7).The insolation of the rooms - as a physical fact of departure - is similar for the three locations, but is strongly influenced by the layout plans of the buildings, which have random orientations, and rooms facing all sides, with therefore strong differences of insolation in the various seasons, for different exposures, and no bioclimatic attention. It should be noted that all the balconies are actually

XII DBMC, Porto, PORTUGAL, 2011 3 Filiberto Lembo internal loggias, surrounded on three sides by walls and railings bordered by two small vertical slots filled with 12 cm wide side, and then they determine strong shadows and stop the passage of air, while (including the absence of suitable eaves sprout) are suitable for accumulating rain water blown by the wind, resulting in stagnant water, water penetration, and therefore internal and external stains.

Surface/Volume ratio is 3:1 for basic "windmill model ", 2.3:1 for two mirror image e 2.6:1 for the same in Lagonegro (six floors high).

3.2 Climatical data

The research, which examined the years 1988 to 1999, showed that, despite being located close together, the three sites have very different climatic conditions, but all with cold winters. Lagonegro is characterized by long, harsh winters with frequent snowfalls and long rainy seasons, and summers are short and cool; Chiaromonte has a humid climate, mild, hot summer's, but quite hard winter' s, with significant rainfall and also (albeit brief) of snow, with large daily temperature ranges, even in summer; Francavilla in Sinni has similar climatic characteristics to the nearby Chiaromonte, but with less rainfall (see Fig.4).

Figure 4. Maximum and minimum temperatures in the three sites, 1988-1999 (a), and Quantity of rain in the three sites, 1988-1999 (b).

The presence of a meteorological station in Lagonegro allowed to conduct a complete analysis of the wind direction and strength between January 1996 and April 2005. The results can be applied in two other locations, with details that say, plano-altimetric configurations on the sites, which influence their exposure to wind and wet clouds, or rain and snow. The remainder of the climatological data of Chiaromonte was derived from weather stations and Valsinni and , and those of the weather station of Francavilla from Agromonte.

It appears that in winter the winds are predominantly from West and South-West (between 200° and 240°), with seasonal average intensities ranging between 1.4 m/s and 3 m/s, unless isolated on a weekly basis (especially during the months of January-February), in which the wind speed reached and even exceeded, the 5 m/s, posing a real threat to the proper maintenance of the functionality of the building envelopes. These periods appear to be also the wettest, so the danger of environmental conditions becomes greater. It's no accident that Basilicata is home to some major wind parks.

It should be noted that while the situation in relation to the orographic Lagonegro building is located in a quiet area at the foot of the slope, those of Chiaromonte found along the slope, in an area prone to depression with the formation of vortices , and those of Francavilla in areas with intermediate situation between depression and the formation of eddies and zones of peace . Have been studied the relationship between the configurations of the buildings and the flows of wind caress them, as previously defined, including in relation to the presence of obstructions such as other buildings, with reference to the form and all height of one and the other, as well as to the direction of the flow of air [Grosso 1997, De Pascalis 2005] (see Figs 5, 6 and 7).

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4 CONSEQUENCIES IN TERMS OF PATHOLOGIES

In Lagonegro , West and South sides, and corners on exposed, affected by strong winds, heavy rain and snow, which caused illness by infiltration of meteoric water in the opaque parts of the facades and in that window, determining the need to ensure, after the construction of buildings, to placing of an insulating coating from outside. In contrast, the leeward side, there is little ventilation.

Figure 5. Wind exposition,, Lagonegro, in most raining period (27-31 January 2004).

In Chiaromonte , buildings are invested by the wind in parallel and a building is partially protected. From technical reports to file, that just the immediate damage and disease have arisen on the facades facing South-West led to the decision to intervene on these fronts with an insulation from the outside, which was then extended to other fronts. Again, the presence of protrusions and recesses resulting in the formation of vortical motion, and the concentration and storage of water in particular points (especially the loggias).

Figure 6. Wind exposition, Chiaromonte, in winter time (seasonal average direction, 225°).

In Francavilla buildings are protected from the prevailing winds from the nearby steep slope. In this case, there are no problems of infiltration water through the walls and windows, but on the contrary, problems, common to almost all housing, resulting from very poor ventilation and lack of internal evaporation of meteoric water, which collects in the recesses and the flat roof, although with lower intensity rainfall than the other two sites (see here above). The spread of diseases from condensing on the walls of housing has been such, that in this case it was necessary to resort to affix isolation from the outside, everywhere, even before the construction works were declared over. But without what turned out to be exhaustive.

Figure 7. Wind exposition, Francavilla in Sinni, in winter time (seasonal average direction, 225°).

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The analysis was carried out on time, building by building, for each apartment and room by room, the three sites, with reference to the Building Rules of the era of design and to feel more hours regulations in force, having the very outset, the ab origine overall failure rate for renewal of the air, particularly serious problem in buildings with walls almost impervious to air and steam, except that the boundary of the frames. It should be noted, moreover, the high humidity 's outdoor air, which in winter is often equal to 72-78%, and therefore makes it ineffective the ventilation made opening windows.

5 MANAGEMENT MISTAKES, PLANNING MISTAKES, CONSTRUCTIVE MISTAKES, REFURBISHMENT MISTAKES, AND THEIR INFLUENCE ON DURABILITY OF BUILDINGS

The analysis, the hygrothermal calculations, reconciliations and regulatory subsequent in-depth reflections, led to highlight the whole chain of errors that led to the serious problems of durability of the buildings in question, which will be listed below, which have compromised their habitability, and still cause serious problems for the occupants.

The form of contract, a call for bids, has allowed them to be bridged the traditional general conditions, referred to the "traditional" system building (in situ concrete pillar-beam system, with infill in double masonry wall, and insulation in between); in this contract, the rules have been suggested by the same manufacturer-designer, and the Commission for the award has not been able to understand that the proposed prefabricated system could not function in the harsh and rainy weather of the sites in question . Or if they have noticed the construction management, which has had to run buildings whose bad behavior was perfectly predictable, where he was referred to the International Recommendations for Computing and Making of Structures in Large Panels C.E.B.-C.I.B.-U.E.A.tc, edited in Italy by Associazione Italiana Tecnico Economica del Cemento, Roma, 1969 [Lugez, 1978], that's the only specific European legislation, existing at' era of 'contract; but a voluntary contract law, which applies only when invoked in the general conditions. In the notice , even if it allowed the participation of the licensees of prefabricated building systems, reference was made to the laws in force in Italy on the stability and safety of buildings in steel and r.c. and prefabricated (Law No. 1086 of 05/11/1971, Law No. 64, 2/2/1974, 3/10/1978 M.D., Circ. Min. No. 6090 of the Public Works' 11/ 8/1969) (where "prefabricated" means the individual structural elements such as floor joists or beams, and non-whole "system buildings"), and then with the notable absence of reference to the Technical Standards C.E.B.-C.I.B.-U.E.A.tc. But what does it say " prefabricated buildings " in the field of housing, but " large panel building "?

And the clear unpreparedness to manage the contracting system buildings that do not know. And, again, in Italy, the technical innovation, and in particular the industrialization 's construction and prefabrication, far from promoting the elevation of the quality of building products, have become the Trojan horse through which bypass the rules, and to ensure a market for products that are obsolescent elsewhere [see Lembo 2010]. Obviously, in this case, the final general conditions, which are attached to the contract, and that have been suggested by the manufacturer, make no reference to the Rules of C.E.B.-C.I.B.-U.E.A.tc. The reason is obvious: if you were referring to this rule, the S.B.S. system could not be taken into consideration. Just one example: the European Regulation prohibits the use of butt joints in the positions they are not easily serviceable, that they only allow planes to land or inside the lodges, here we have a building six floors above ground, and the other three or four floors. All this, in places hilly or mountainous areas, with high temperature amplitudes (and hence a strong potential differential movements of the panels), and intense rainfall. And moreover, a management mistake , or a design mistake take place in such a building system based on sandwich panels rigidly connected by ribs boundary at every 60 cm, abandoned the system, first in France and then throughout Europe after the first oil shock of 1973, for reasons of energy conservation, and the inability to solve the generalized problem of thermal bridges, and the resulting diseases from condensation? [Lembo 1977]? The writer believes that it is a management mistake .

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For an expert in large prefabricated bearing panels would have been impossible to make good-value of the average transmittance of the facade panels indicated by the company proposing: the analytical tests performed show that a front panel S.B.S. with windows, given the thermal bridges, has an average transmittance of non-U = 0.64 W/m 2K, but W/m 2K of 1.49, with the risk of generalized condensation in all units of all three sites, because (see Rules C.E.B.-C.I.B.-U.E.A.tc) f is always greater than amply 0.25 [Lugez, 1978, cit., pagg. 64-65]. It's also, of course, a management mistake , for buildings in different geographical, topographical and climatological which are seen, and that the administration surely knew, and not to seek to impose through the general conditions that the walls of the buildings had such a typology, to allow them a high degree of impermeability to rain. In Italy there is not existing legislation such as that of the French DTU 20.11 or 20.01, but nothing prevents you (and prohibits) in Italy that could (and can) be prescribed, for example, with reference to that legislation, which offers the Company should (should) provide for the external walls of the third type ("walls drained” or directly "curtain walls and drained"). The outer wall of the System S.B.S. is classified as a wall of the first type (" hydrophilic material in contact with insulating wool ") (corresponding to the ribs there is only one material, from internal to external) entirely unsuitable to the conditions of exposure there. So much so that even the application of an external insulation system thin render-on-insulator (which led to become the walls of IIa type to " cut capillary vertically in wall thickness, consisting of an-hydrophilic insulating ") was able to solve, under certain conditions, the problems of waterproofing the walls.

It's still a management mistake not to realize that in a building system with walls and floors made of two slabs r.c. prefab class R 30, each constituent vapor barrier, and which are horizontal and vertical tubular channels, you need precise control of the design solution not only structural and technological, but also plants, and careful monitoring on construction methods to ensure that ventilation of the rooms comply with the provisions of the Standards in order to keep low the relative humidity to internal environments, and that meteoric water cannot enter from the shell or facade, as happens in the buildings concerned, then that liquid water is conveyed in the most disparate from the tubular blank panels. If this happens, have a direct impact on the disease by condensation and the quality of indoor air, so be it (at least for building these systems), also in southern Italy, the centralized control of the change of air, heat recovery, as in passive houses in Germany, but with de- humidification too. Never mind, if you miss the traditional manual control of opening the windows, which is seen per tabulas they are usually held closed for too long, as naive defense against the errors and shortcomings in the design, construction that is part of that plant.

It's still quite a mistake in the management control of the proposed solution rather than a design mistake to take the good (in the race [call for bids], and then to construction management, and then Test) solution for the roofs which provides, on the multitubular slabs: 1.) in all three sites, a sheet of kraft paper bitumen (which the proposed project poses as vapor barrier); 4.5 cm of glass wool; a ventilated cavity with openings to the external, high ranging from 0 to 50 cm in Chiaromonte and Francavilla, from 0 to 150 cm in Lagonegro; clay tiles and then resting on brick walls every meter; a slab of concrete and the coating and waterproofing bitumen sheet in Chiaromonte and Francavilla, cement tiles in Lagonegro; 2.) on the edge of roofs of all three sites, a channel of internal collection of rain water, four feet wide, and consists of a simple slab of concrete with a slope no insulation, followed by a bitumen sheet turned up to 20 cm high, without flashing fixing higher, and no insulation over the surface of the raceway.

Obviously, the verification of Glaser shows that interstitial condensation occurs over the entire surface of the roofs. Obviously, the thermal bridge at the raceway has devastating consequences. Obviously, if the sheath of the channel has some gaps, the water falls vertically along the channels of the panels, and appear where it happens. But even more surprising to note that in the speeches of thermal retro-fitting completed by the owner of the body housing, the insulation from outside the jetties have been stopped under the crown, leaving intact the thermal bridges, as they stopped at the bottom connection between the first floors and the cellar, leaving intact the lower thermal bridges.

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And yet, who is at fault if there are widespread phenomena of capillary at basement and ground floors? Who has not provided the planned cuts of capillary action, or who he has not alleged in the general conditions, and imposed in the Executive? Who is responsible if the basement or semi- basement panels are directly matched to the ground, without protection from cavities' ground water, and then soaked with water, making it unsuitable environments, even for only deposit? Who did not enforce, in the design and execution, the requirement to be met, or who, designing, it has not taken into account? And, with regard to durability, to accept a construction system that had such thin slabs and ribs connecting just 3.5 cm, mean time to accept a very risky bet in terms of durability, if you think that the carbonation depth reaches usually 25 mm in 25 years, and if it is true that the Directives Communes pour l' Agrément des Procedés de construction par grands panneaux lourds préfabriqués (Cahiers du C.S.T.B. n. 696, June 1966) showed even then that "... all the materials, components, works, etc., with non-replaceable maintenance, must be such that we can estimate that they will retain for a period of at least 50 years, if the subject of regular maintenance treatments, the characteristics that allow them to remain consistent with the rules previously stated . .. "

5 CONCLUSIONS

The analysis of environmental characterization has allowed to understand that most of the diseases and the consequent problems of durability of these buildings has its origin in errors in evaluation reports. The management would have to scrap a construction system that is patently unfit to perform well in a difficult environment. The geo-climatic characteristics have been the detonator of defects in design and meta-design that would have been recognized already in the tender process. Once again, the main responsible for the lack of rules that ensure the quality and durability of the buildings is the bidding process – call for bids . Retrofitting interventions have had only heat content and were not even aimed at substantially improving the meteoric water proofing of roofs and façades. They were also partial, and not sufficiently corrected by the technical point of view. It should have taken more complete solutions (façades ventilated and drained to the sides most vulnerable, isolated and well- designed covers, complete isolation from the outside, perimeter insulation of buildings from the ground, pieces of capillary action, automatic ventilators, dehumidifiers). It requires that Contracting Authorities must achieve the know-how suitable to the challenges posed by technological progress.

ACKNOWLEDGMENTS

Many thanks to Eng. Adele Oliveto, for his thorough research on the topic, and to ATER, now EPER of , represented by its CEO, Eng. Raffaele Vita, and its Director, Arch. Michele Bilancia, for the great willingness to make available the original design documentation.

REFERENCES

Lembo F. 1977, Le tecnologie di industrializzazione ed i sistemi di prefabbricazione utilizzati nell’edilizia civile , Special Issue n. 7-8, July-August 1977 “ Industrializzazione dell’ edilizia e prefabbricazione – Parte 2^ ” of “ L’ Industria Italiana del Cemento”.

Lugez, J. 1978, La prefabbricazione a pannelli nell' edilizia residenziale , edited by F. Lembo, Edizioni C.E.L.I., Bologna.

Grosso, M. 1997, Il raffrescamento passivo degli edifici , Maggioli Editore, Milano.

Lembo, F. & Marino F.P.R. 2002, Il comportamento nel tempo degli edifici. Cause di degrado e soluzioni progettuali dei sistemi edilizi "tradizionali" ed "industrializzati". Casi di studio, EPC libri, Roma, ISBN 88-8184-241-6.

De Pascalis, S., 2005, Progettazione Bioclimatica , Dario Flaccovio Editore, Palermo.

Lembo, F. 2010, Causes: Processes in which there is lack of Quality Control, Errors in Planning or Executing , CIB W 86 State-of-The Art Report , CIB W 86 Annual Meeting, Santander 29 October 2010.

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