L3-Building-Set-Out

CSTMAS301: BUILDING SET OUT Competence : Set out a building

RTQF LEVEL: 3 CREDITS: 9 LEARNING HOURS : 90

SECTOR: Construction SUB-SECTOR: Masonry

ISSUE DATE: 06/01/2020

MODULE STRUCTURE Learning Unit 1: Clear the site

Learning outcomes Contents

1.1. Assess the site  Types of soil and vegetation condition  natural features and built environment

 Topographic characteristics of earth

1.2. Identify harmful  Harmful waste to environment (industrial waste) waste to environment  removing waste:  manual and mechanical techniques and Safety precaution applied

1.3. Clear unnecessary  Classification of trees and plants trees, Tree trunks and cut grasses  Techniques of clearing trees and plants:  Manual  Mechanical 1.4. Remove top soil  Soil types and characteristics  Removing top soil: Manual and mechanical techniques

Learning Unit 2: Set profile

Learning outcomes Contents

2.1. Select hand survey  Identification of hand survey tools and equipment and their use: tools and equipment  Plumb bob, spirit level and hose pipe.  Dumpy levels, theodolite and accessories

2.2. Set up levelling  Setting levelling devices and instruments: plumb bob, spirit level, devices hose pipe dumpy levels and theodolite

2.3. Take data from  Parts of dumpy level and theodolite. dumpy level and theodolite.  Read data from dumpy level and theodolite.  Fill levelling book 2.4. Demarcate  Setting out methods: foundation pegs and  3-4-5 Method lines  Builder’s square method  Foundations (Marking out the measurements on the ground

,Selecting the pegs and lines Placing pegs)

Learning Unit 3: Excavate foundation

Learning outcomes Contents

3.1. Delimit the surface to  Setting out foundations and pegging be excavated

3.2 Dig out foundation  Theory of the angle of repose trench  Digging trenches

 Removing the excavated soil

 Timbering: Supporting the sides of an excavation  Safety precautions 3.3. Separate top soil and  removing topsoil away from other reusable material refill soil  Use of strength soil and filling

3.4 Make smooth sides and  Checking depth and surface level with a builder's level level base  Impact of levelling trench bases and making smooth sides:  Fasten foundation works  Provide structural stability to foundation  Avoid mortar wastage

INTRODUCTION TO THE MODULE Building set out or setting out of building refers to the act of measuring and marking out a full size plan of a building on site. This core module describes the performance out comes skills, knowledge and attitude to set out a building on the site where the learner will be able to clean the site, and then set the levelling instruments and demarcate the foundation, walls and columns on pegs, profiles and lines as required LEARNING UNIT 1. CLEAR THE SITE This is the first task of site preparation. The site should be in a cleared and graded condition. It involves the removal of trees, demolishing buildings, removing any and all old underground infrastructure, and any other obstacles that might affect the construction process of the project to be done.

Site clearance is done by a combination of manual (using spades, hoes, wheelbarrow, pick) and mechanical (using Mechanical shovel, back actor, bulldozer, dump truck, mechanical auger, pneumatic drill, tipper truck methods.

L.O.U 1.1. ASSESS THE SITE CONDITION

Investigating the site: When the client identifies a site, then the building surveyor investigates it to find out the: o The strength of the soil, because this affects the design of the foundations o Type of the soil which will be excavated o Amount of the water in the ground because this affects the design of the foundations and working procedures. o Amount of clean or contaminated ground o Amount that the ground slopes o Access to services such as mains water, electricity and drainage o Best position for the building in terms of the local climate o Position of natural features such as trees, rocks, and streams. o Position of other buildings near the site o Location of site boundaries and access road.

Evaluating or estimating the nature, ability or quality of the site. 1.1.1 Types of soil and vegetation  Soils Definition: the substance on the surface of the earth in which plant grow. Or, Soil is the substance on the surface of the earth on which buildings are constructed.

Classification of soil Coarse-grained soils Coarse-grained soils include sands and gravels with a low proportion of voids, negligible cohesion when dry, high permeability and slight compressibility, which takes place almost immediately on the application of load.

Fine-grained soils Fine-grained soils include the cohesive silts and clays with a high proportion of voids, high cohesion, very low permeability and high compressibility, which takes place slowly over a long period of time. There are of course soils that can be classified in between these two Extremes. Divides particle sizes as follows:

■ Clay particles: less than 0.002 mm. ■ Silt particles: between 0.002 and 0.06 mm. ■ Sand particles: between 0.06 and 2 mm. ■ Gravel particles: between 2 and 60 mm. ■ Cobbles: between 60 and 200 mm.

Types of soil 1. Soil Type: Sand

Sand soil has the largest particles among the different soil types. It’s dry and gritty to the touch, and because the particles have huge spaces between them, it can’t hold on to water. Water drains rapidly, straight through to places where the roots, particularly those of seedlings, cannot reach. Plants don’t have a chance of using the nutrients in sandy soil more efficiently as they’re swiftly carried away by the runoff.

2. Soil Type: Silt

Silt soil has much smaller particles than sandy soil so it’s smooth to the touch. When moistened, it’s soapy slick. When you roll it between your fingers, dirt is left on your skin.

Silt soil retains water longer, but it can’t hold on to as much nutrients as you’d want it to though it’s fairly fertile. Due to its moisture-retentive quality, silty soil is cold and drains poorly.

Silt soil can also easily compact, so avoid trampling on it when working your garden. It can become poorly aerated, too.

3. Soil Type: Clay

Clay soil has the smallest particles among the three so it has good water storage qualities. It’s sticky to the touch when wet, but smooth when dry.

Due to the tiny size of its particles and its tendency to settle together, little air passes through its spaces. Because it’s also slower to drain, it has a tighter hold on plant nutrients. Clay soil is thus rich in plant food for better growth. 4. Soil Type: Peat

Peat soil is dark brown or black in color, soft, easily compressed due to its high water content, and rich in organic matter

Although peat soil tends to be heavily saturated with water, once drained, it turns into a good growing medium. In the summer though, peat could be very dry and become a fire hazard. The most desirable quality of peat soil, however, is in its ability to hold water in during the dry months and its capacity to protect the roots from damage during very wet months.

Peat contains acidic water, but growers use it to regulate soil chemistry or pH levels as well as an agent of disease control for the soil. When wet peat soil is rolled, you won’t form a ball. It’s spongy to the touch and when squeezed, water could be forced out.

5. The Soil Type: Loam

The type of soil that gardens and gardeners love is loamy soil. It contains a balance of all three soil materials—silt, sand and clay—plus humus. It has a higher pH and calcium levels because of its previous organic matter content.

Loam is dark in color and is mealy—soft, dry and crumbly—in your hands. It has a tight hold on water and plant food but it drains well, and air moves freely between soil particles down to the roots.

Characteristics of Different Types of Soil

Sandy Loam Clay Runs between your fingers Feels crumbly Feels slippery when wet Few lumps Soft and feathery Dry clay is very hard When moistened and When moistened and When moistened and squeezed, it will not stay squeezed, it will stay squeezed, it will stay together together forming a loose together forming a tight ball ball Light brown Dark brown or black Color is determined by the minerals it contains Mostly minerals Balance between mineral Mostly minerals, little particles and organic humus matter Little food for plants Lots of nutrients for plants Fine texture Dries quickly Absorbs water very well Small pore size

These are discontinuous and they grow in gravel and sand soils Savanes, mountain, tropical,

1.1.2 Natural features and built environment a) Natural features are all things that are not made by people Examples: plants, trees, rocks, lake, sea, streams,… b) Built environment refers to the human made surrounding that provide the setting for human activity. Examples: buildings, road, cars, …

1.1.3 Topographic characteristics of earth Topography is the study of the shape and features of the surface of the earth. Topographic refer to the arrangement of the physical features of the area.  Characteristics of earth Physical characteristics of Earth Physical characteristics include shape, size and composition. 1. Shape: The shape of the Earth has been proven by ships circling the Earth, as well as from pictures of the Earth taken from the space vehicles.

2. Size: The diameter of the Earth at the equator is 12,756 km (7,926 miles), and its circumference or distance around the Earth at the equator is 40,075 km (24,901 miles). 3. Composition: The composition of the Earth consists of the solid and liquid portion and the atmosphere or gaseous portion.

The topographic characteristic of the earth are hills, mountains, valleys, Volcanoes, oceans, rivers.

1.2.Identify harmful waste to environment 1. Harmful waste to environment (industrial waste) What is harmful waste or Hazardous Waste? Anything that has been thrown away that can still potentially harm its surroundings and those who dwell in them is considered hazardous waste. This can be anything from chemical waste and materials left over from manufacturing to household garbage such as cleaning solutions, batteries, and non- biodegradable plastics. Examples: paint, acid, oil, cleaners, metal, gases,… 2. Removing waste: 1. manual remove 2. mechanical techniques

In manual method, we can use various tools and equipment that help us to remove those wastes are in site we want to build on. The tools we may use are:

Hoes Spades Safety helmets Shovels Face mask Etc. Pick axes Boots Buckets Glooves For the case of mechanical method,often there is some machines that are used to remove waste in the ground,where we want to build.some of machines that are used are follow:

Back hoe or drag shovel Loading shovel Forward loader Dragline Grab (drag bucket) Road lorries Dumpers Dozers Scrapers Graderss Safety precaution applied 1. Hard hat or helmets, Groves Mask Overall Strong boots Should be used while handling chemical of toxic nature. It is preferred that at least two persons should be present at all time while working with chemicals. 2. Heating flammable solvent may cause fire. Such work must be carried out in a well-ventilation fume-cupboard. 3. When your body is contact with the chemical, flush your body with plenty of fresh water and report the accident to the laboratory technician. 4. Waste products and disposals must be discharged with proper neutralization. If the material to be disposed is extremely toxic or poisonous, the material should be kept in closed container and sent to appropriate agency for proper disposal. 5. Use storage containers that are compatible with the type of waste stored, and are made of durable, weather- and corrosion resistant materials. 6. Ensure wastes are stored in an area that is inaccessible to unauthorized

1.3. Clear unnecessary trees, Tree trunks and cut grasses TREES Timber, the basic raw material of carpenter and joiner, is the product of the woody perennial plant which we all know as “tree”

Trees differ from most other types of plant, not only an account of their sizes and strength, but also in the way in which they grow.

PARTS OF A TREE

A tree may be regarded as having three main parts namely: Roots, Trunk and the crown.

The roots: serve to anchor the tree firmly into the ground, to support its weight and absorb water and soluble minerals salts from the soils.

The trunk: to support the crown and conduct food and water

The crown of tree –the branches, leaves and twigs (small thin branches of a tree) The classification as soft wood and hard wood has commercial importance. The difference between soft wood and hard wood is given below: 1. in soft wood annual rings are seen distinctly whereas in hard wood they are indistinct. 2. The colour of soft wood is light whereas the colour of hard wood is dark. 3. Soft woods have lesser strength in compression and shear compared to hard woods. 4. Soft woods are light and hard woods are heavy. 5. Fire resistance of soft wood is poor compared to that of hard wood. 6. The structure of soft wood is resinous while structure of hard wood is close grained. The cross-section of an exogenous tree is as shown in the Fig below. The following components are visible to the naked eye:

Fig. Cross-section of exogenous tree

1. Pith: It is the inner most part of the tree and hence the oldest part of exogeneous tree when the plant becomes old, the pith dies and becomes fibrous and dark. It varies in size and shape. 2. Heart Wood: This is the portion surrounding pith. It is dark in colour and strong. This portion is useful for various engineering purpose. This is the dead part of wood. It consists of several annular rings. 3. Sap Wood: It is the layer next to heart wood. It denotes recent growth and contains sap. It takes active part in the growth of trees by allowing sap to move in upward direction. The annual rings of sap wood are less sharply divided and are light in colour. The sap wood is also known as laburnum. 4. Cambium Layer: It is a thin layer of fresh sap lying between sap wood and the inner bark. It contains sap which is not yet converted into sap wood. If the bark is removed and cambium layer is exposed to atmosphere, cells cease to be active and tree dies. 5. Inner Bark: It is a inner skin of tree protecting the cambium layer. It gives protection to cambium layer. 6. Outer Bark: It is the outer skin of the tree and consists of wood fibres. Sometimes it contains fissures and cracks. 7. Medullar Rags: These are thin radial fibres extending from pith to cambium layer. They hold annular rings together.

PROPERTIES OF TIMBER Properties of good timbers are: Colour: It should be uniform.

Odour: It should be pleasant when cut freshly. Soundness: A clear ringing sound when struck indicates the timber is good. Texture: Texture of good timber is fine and even. Grains: In good timber grains are close. Density: Higher the density stronger is the timber. Hardness: Harder timbers are strong and durable. Warping: Good timber does not warp under changing environmental conditions. Toughness: Timber should be capable of resisting shock loads. Abrasion: Good timber does not deteriorate due to wear. This property should be looked into, if timber is to be used for flooring. Strength: Timber should have high strength in bending, shear and direct compression. Modulus of Elasticity: Timber with higher modulus of elasticity is preferred in construction. Fire resistance: A good timber should have high resistance to fire. Permeability: Good timber has low water permeability. Workability: Timber should be easily workable. It should not clog the saw. Durability: Good timber is one which is capable of resisting the action of fungi and insects attack Defects: Good timber is free from defects like dead knots, shakes and cracks.

SEASONING OF TIMBER This is a process by which moisture content in a freshly cut tree is reduced to a suitable level. By doing so the durability of timber is increased. The various methods of seasoning used may be classified into: i) Natural seasoning (ii) Artificial seasoning. (i) Natural Seasoning: It may be air seasoning or water seasoning. Air seasoning is carried out in a shed with a platform. This is a slow but a good process of seasoning.

Water seasoning is carried out on the banks of rivers. The thicker end of the timber is kept pointing upstream side. After a period of 2 to 4 weeks the timber is taken out. During this period sap contained in the timber is washed out to a great extent. Then timber is stalked in a shed with free air circulation. (ii) Artificial Seasoning: In this method timber is seasoned in a chamber with regulated heat, controlled humidity and proper air circulation. Seasoning can be completed in 4 to 5 days only. The different methods of seasoning are: (a) Boiling (b) Kiln seasoning (c) Chemical seasoning

(d) Electrical seasoning. (a) Boiling: In this method timber is immersed in water and then water is boiled for 3 to 4 hours. Then it is dried slowly. Instead of boiling water hot steam may be circulated on timber. The process of seasoning is fast, but costly. (b) Kiln Seasoning: Kiln is an airtight chamber. Timber to be seasoned is placed inside it. (c) Chemical Seasoning: In this method, the timber is immersed in a solution of suitable salt. (d) Electrical Seasoning: In this method high frequency alternate electric current is passed through timber.

DEFECTS INTIMBER Various defects which are likely to occur in timber may be grouped into the following three: (i) Due to natural forces (ii) Due to defective seasoning and conversions. (iii) Due to attack by fungi and insects (i) Defects due to Natural Forces: The following defects are caused by natural forces: (a) Knots (b) Shakes (c) Wind cracks (d) Upsets (a) Knots: When a tree grows, many of its branches fall and the stump of these branches in the trunk is covered. In the sawn pieces of timber the stump of fallen branches appear as knots. Knots are dark and hard pieces.

(b) Shakes: The shakes are cracks in the timber which appear due to excessive heat, frost or twisting due to wind during the growth of a tree. Depending upon the shape and the positions shakes can be classified as star shake, cup shake, ring shakes and heart shakes

(d) Upsets: Figure 1.12 shows a typical upset in a timber. This type of defect is due to excessive compression in the tree when it was young. Upset is an injury by crushing. This is also known as rupture.

(ii) Defects due to Defective Seasoning and Conversion: If seasoning is not uniform, the converted timber may warp and twist in various directions. Sometimes honey combining and even cracks appear. This type of defects is more susceptible in case of kiln seasoning. In the process of converting timber to commercial sizes and shapes the following types of defects are likely to arise: chip marks, torn grain etc. (iii) Defects due to Fungi and Insects Attack: Fungi are minute microscopic plant organism. They grow in wood if moisture content is more than 20°C and exposed to air. Due to fungi attack rotting of wood, takes place. Wood becomes weak and stains appear on it. Beetles, marine borers and termites (white ants) are the insects which eat wood and weaken the timber.

USES OF TIMBER

1.3.2 TECHNIQUES OF CLEARING TREES AND PLANTS MANUAL METHOD Land can be cleared using several different methods. When a land owner decides to clear land, it is important to carefully decide which method to choose. Part of this decision will be based on what the land will be used for after it is cleared, and how much time and cost is involved in the clearing. Trees can be cleared by manual method with hand tools like: Hoes, spades, Machetes, and pick axes MECHANICAL METHOD Trees and plant can also be cleared by Mechanical method by using Bulldozers for harvesting any large trees that are on your land before you bring in a bulldozer. Nice size trees can be cut and sold for logs. Use a bulldozer to completely clear an area of land after it is harvested. The bulldozer can then push away debris from the harvesting, and the bulldozer will push over stumps and fairly small trees and bushes Others equipments are mechanical shovel, back actor etc.

1.4 Remove top soil

 Soil types and characteristics (seen above)  Removing top soil:

 Manual and by using hand tools like: Hoes, spades, Machetes, and pick axes

 mechanical techniques Removing top soil by Mechanical method Mechanical equipment makes the job much easier. Following are the equipment that can be used for various types of work.  1. A bulldozer can quickly push the topsoil  2. A back actor is used for digging pits for column or piers  3. A mechanical auger is used for digging holes for piles  4. Tipper truck for transporting large amount of soil  5. Dump truck for transporting small quantity of soil at a short distance  6. Draglines for digging deep foundations  7. Face shovel: for pushing the soil forward  8. Pneumatic drill for drilling into solid rock

Fig. bulldozer Fig .back actor

Fig. Tipper truck Fig. Mechanical auger

Fig. dump truck Fig. Mechnanical shovel

Fig. dragline Pneumatic drill

LEARNING UNIT 2: SET PROFILE

2.1 Select hand survey tools and equipment

 Identification of hand survey tools and equipment and their use:  Plumb bob or plummet: is a weight with a pointed tip on the bottom, suspended from a string. It is used for checking vertical reference.

 Spirit level: is a tool designed to indicate whether a surface is horizontal or vertical.

 Hose pipe: is a flexible hollow tube designed to carry fluid. In construction hose pipe is used for horizontal levelling when a long wall is being constructed.

 Dumpy level: is an optical leveling instrument used to establish or check points in the same horizontal plane.

Parts of dumpy Level

Dumpy Levels can be used for:

 Determining the height of a particular point.  Determining differences in height between points.  Drawing contours on a land.

 Providing data to calculate volumes for earthworks.  Setting out level surfaces for construction.  Setting out inclined surfaces for construction.

 Theodolite and accessories Theodolite: is a precision instrument for measuring distance and angles in horizontal and vertical planes. Parts of Theodolite and their Functions Following are the parts of a theodolite: Telescope Vertical circle Index frame The standards The upper plate The lower plate The leveling head The shifting head Plate level Tripod Plumb bob Magnetic compass

Telescope A telescope is a focusing instrument which has object piece at one end and eye piece at the other end. It rotates about Horizontal axis in vertical plane. Vertical Circle Vertical circle is fitted to telescope and moves simultaneously with telescope. It has graduation in each quadrant numbered From 0 to 90degrees The Standards The standards are the frames which supports telescope and allow it to rotate about vertical axis. The Upper Plate This is also called as vernier plate. The top surface of upper plate gives support to the standards. It also consists an upper Clamping screw with respect to tangents screw which helps to fixing it to the lower plate. The Lower Plate This is also called as scale plate. Because it contains a scale on which 0 to 360 readings are graduated. It is attached to the outer spindle and consists lower clamping screw. The Leveling Head The leveling head contains two parallel triangular plates called as tribratch plates. The upper one is known as upper tribratch Plate and is used to level the upper plate and telescope with the help of leveling screws provided at its three ends. The lower One is called as lower tribratch plate and is attached to the tripod stand.

The Shifting Head Shifting head also contains two parallel plates which are moved one over the other with in small area. Shifting head lies below the lower plate. It is useful to centering the whole instrument over the station. Plate Level Plate levels are carried by the upper plate which is right angles to each other with one of them is parallel to trunnion axis. These plate levels help the telescope to settle in exact vertical position.  Accessories of a theodolite Tripod Tripod is a stand on which theodolite is mounted. It should place in such a way that theodolite should be in exact Leveled position. The tripod has legs with steel shoes at their ends. These hold the ground strongly without any movement when placed. Leveling staff: is a graduated wooden or aluminum rod used with a leveling instrument to determine the difference in height between points.

2.2. Set up levelling devices Setting leveling devices and instruments: plumb bob, spirit level, hose pipe dumpy levels and theodolite Definition of leveling Leveling: means the determination of the difference in elevation of various points on the ground. TERMS USED IN LEVELLING 1. Benchmarks: A benchmark is a relatively permanent reference point, the elevation of whichis known. It is used as a starting point for levelling or as appoint upon which to close for a check.

2. Datum: A reference point from which other points in a survey are measured from. A datum may be a known point within an existing survey grid or it may be any arbitrary point. 3. Mean Sea Level (MSL): MSL is the average height of the sea for all stages of the tides. 4. Reduced Levels (RL): The level of a point taken as height above the datum surface is knownas RL of that point. 5. Back sight: A backsight is a reading taken on a position of known coordinate(s). Since a survey progresses from a point of known position to points of unknown position, a backsight is a reading looking "backward" along the line of progress 6. Foresight: A foresight is a reading taken on a position of unknown coordinate(s). Since a survey progresses from a point of known position to points of unknown position, a foresight is a reading looking "forward" along the line of progress 7. Intermediate sight: reading taken after back sight and before foresight. 8. Change point or turning point: is the point on which foresight is taken and then instrument is shifted and set to new position, then back sight is taken. 9. Height of collimation: is the height of instrument. 10. Plane of collimation: is the reduced level of the plane of sight with respect to datum selected. leveling instruments: 1. Dumpy level. Setting up the level i. Setting up the instrument: this is the process of mounting the instrument like the level Over the tripod and clamps it with the screw. ii. Leveling up the instrument: by using foot screws with reference to the plate level, accurate leveling will be done. iii. Elimination of parallax: by focusing the eye piece and bring the image of the objects in The plane of cross hairs.

2. Theodolite

Setting up over a point i. Stand closed tripod on the ground, undo transport strap, loosen lock bolts and lift tripod to extend the legs evenly and tighten lock bolts ii. Place tripod over the setup point, move one leg out from the point about 0.5m and step into the ground

21 iii. Lift the 2 free tripod legs slightly off the ground while viewing down through the instrument securing bolt in the centre the tripod top plate and place over the setup point, keeping the top plate of the tripod relatively level iv. Secure theodolite on the tripod v. While looking through the optical plummet, slightly lift the 2 free legs and position the instrument over the setup point vi. Step in the tripod legs vii. Use the 3 adjusting screws on the theodolite so optical plummet is on the setup point viii. While viewing the bulls eye level adjust the legs up or down until level, taking care to stand on the leg being adjusted so it does not pull out of the ground ix. Level the theodolite positioning the spirit level first parallel with 2 leveling screws , then turn 120 degrees and use the third leveling screw to level the spirit level, recheck first position x. Once level view optical plummet to verify over the setup point xi. Loosen the mounting screw to move the plummet over the setup point if necessary and retighten xii. Recheck the instrument level

2.3. Take data from dumpy level and theodolite

 Read data from dumpy level and theodolite. The dumpy levels or theodolites have perpendicular cross hairs. There are the two short cross hairs above and below the main cross hair.

The difference between upper reading & Lower reading is multiplied by 100 to give you the distance from where you are to where the staffs is Example:

Upper Reading: 2.218

Lower Reading: 2.163 = 0.055 x 100= 5.5

Distance between Staff & instrument

= (Upper Reading - Lower Reading) x 100

= (2.218 – 2.163) x 100

Distance between staff & instrument = 5.5 metres

the levelling staff there are various types of graduated staves. out of all, the "sop with telescopic staff" is commonly used. the purpose of a levelling staff is to determine the amount which the station (foot of the staff) is above or below the line of sight by.

Adjustments of instrument Temporary adjustments Temporary adjustments are those kinds of adjustments that the user of the instrument will perform Every time he is going to perform any task while using the instrument, such as elimination of parallax. It is a set of everyday adjustment to the level during the time it is in use. It includes: i. Setting up the instrument: this is the process of mounting the instrument like the level Over the tripod and clamps it with the screw. ii. Leveling up the instrument: by using foot screws with reference to the plate level, accurate leveling will be done. iii. Elimination of parallax: by focusing the eye piece and bring the image of the objects in The plane of cross hairs. 2. Permanent adjustments Permanent adjustment is carried out by the manufacturer of the instrument for putting in good looking Conditions of the operator.

Elimination of parallax Parallax is the apparent movement of the image produced by movement of the observer's eye at the eyepiece. It is eliminated by focusing the telescope on infinity and then adjusting the eyepiece until the Cross-hairs appear in sharp focus. The setting will remain constant for a particular observer's eye. Fill leveling book All leveling shall be booked in either level books or leveling sheets which shall be retained as Permanent records. REDUCING THE LEVELS Two methods are in general use:  The "rise and fall" method and  The "height of collimation" method. a. The "rise and fall" method Rules used when booking levels i. The first (and last) reduced level is on an Ordnance Bench Mark (OBM) or a Temporary Bench Mark (TBM) ii. Following line by line down the page calculating the rise or fall between consecutive staff readings. iii. A rise occurs if the first staff reading is greater than the second staff reading in any consecutive pair of staff readings. iv. A fall occurs if the first staff reading is less than the second staff reading in any consecutive pair of staff readings. v. Add the rise or subtract the fall from the preceding reduced level to obtain the new reduced level, Entered on the same line as the rise or fall.

Level book note for Rise and Fall method

The advantage of the rise and fall method is that it is the simplest method of booking and checking the calculations on site. Example 2.

Checks: 1. Σ B.S. - Σ F.S. =4.287 – 4.287 = 0 m 2. Σ Rise- Σ fall = 2.582 –2.582 = 0m 3. Last R.L. - First R.L.= 86.452 - 86.452 =0m Sum of backsights - sum of foresights = first reduced level - last reduced level = sum of rises - sum of Falls = first reduced level - last reduced level. b. HEIGHT OF PLANE OF COLLIMATION (HPC) METHOD It consists of finding the elevation of the plane of collimation for every set up of the instrument; and then obtaining the reduced level (RL) of points with reference to the respective plane of collimation.

This survey is booked as shown below. It starts and ends on the same OBM

Height of collimation method (height of instrument) 1. Booking is the same as the rise and fall method for back-, intermediate- and foresights. There Are no rise or fall columns, but instead a height of collimation column. 2. The first back sight reading (staff on datum, benchmark or RL) is added to the first RL giving the height of collimation. 3. The next staff reading is entered in the appropriate column but on a new line. The RL for the Station is found by subtracting the staff reading from the height of collimation 4. The height of collimation changes only when the level is moved to a new position. The new Height of collimation is found by adding the back sight to the RL at the change point. 5. Please note there is no check on the accuracy of intermediate RL's and errors could go Undetected.

Comparison between the two methods of reducing levels

2.4 Demarcate foundation pegs and lines Demarcate: set the boundaries or limit, to mark or determine the limit Setting out a building

Definition of setting out Setting out refer to the act of measuring and marking out a full size plan of a building on site. FACTORS TO BE CONSIDERED WHEN SELECTING A BUILDING SITE - Elevation of site, elevated sites are generally preferable to low lying ones, being drier and easier to drain. - Availability of facilities e.g. hospital, transport etc - Availability of services e.g. water, electricity, sewage, etc - Types and conditions of subsoil e.g. gravel, sand, clay etc - Before any building work can commence, the area must be levelled i.e. reducing levels

STEPS INVOLVED FOR SETTING OUT OF BUILDING - Establish the baseline - Set out the right angle at the correct length and check the diagonals - Set up the profile boards to allocate the width of the trench, foundation and walls. - They should be far apart and wide enough not to obstruct excavation work.

METHODS OF SETTING OUT A RIGHT ANGLE BUILDING

- Typical builders square or steel square method - 3-4-5 method or Pythagoras theorem “ the square of hypothesis of right angle triangle is equal to the sum of square of the other two sides” - Levelling instruments - Prismatic square method

PROCEDURES

The 3,4,5 method

Mark out the base line from the road by measuring the required distance from the centre of the road or by stretching a line along an existing building to the proposed site.

The base line is then represented by a line known as front line or ranging line, which also marks the front wall of the buildings.

Mark out the overall length of the building by driving pegs at A and B along the front line obtain two steel tape measures. Mark out four equal distances on the front line starting from the corners peg at B. These distances may be in any unit of measurement, i.e. millimetres, metres, etc. Pull a tape measure from point B to C and ask an assistant to hold it, ready with a hammer and a peg.

Pull the second tape from the fourth mark at D on the front line to point E on the first tape, the distance 5m, if using metres, on tape DE should coincide with the point 3m on tape BEC. Then the angle B is 900(from, pythagoras’theorem). If the point do not coincide, the tape BC.

THE BUILDER’S SQUARE METHOD

- Set out the front line in the usual manner with pegs, - Place the builder’s square so that the front line touches one side of the square right through its length - Stretch a line from the corner pegs so that it is parallel to the second side of the square and establishes the third peg. - A corner of angle 900 is thus obtained. - With the aid of tape measure, mark the length and breadth of the proposed building, - Transferring the builder’s square to the remaining corners and repeating the above operations, a simple rectangular building can be set out. - After establishing the four corner pegs, profiles may be erected in the same way as described above.

Note that the builder’s square method can only be used with accuracy for small buildings.

Levelling instruments

Levelling instruments are used to run lines, to lay-out angles and to ascertain various differences in elevation during construction of a building and its foundation. These include:

(i) Spirit level (ii) Plumb bob (iii) Dumpy level

Dumpy level and transit level. These are precision instruments incorporating a telescope, levelling devices, horizontal and vertical cross-hairs and vertical angles. Checking diagonals

After you create a right angle, all other lines are produced parallel to the original line To check where the building is square, the diagonals are measured to ensure they are the same length. If you find they are not, then there is an error either in original right angle or in the measurement of the parallel sides.

Installing profiles

Where do you place profiles? They are be placed at least 1m away from the proposed excavation when manual excavation methods are used (pick and shovel) and at least 1.5m away when mechanical excavation methods are used ( back hoe, trench excavator). This space allows for ease of access and prevents the profiles falling back into the excavated area.

Tools, materials and equipment used in setting out.  String for string lines  Timber for profiles and pegs  Straight edge  Hummers  Hand saws  Marking equipment  Nails  Spirit level  Tape measure.

LEARNING UNIT 3: EXCAVATE FOUNDATION 3.1 Delimit the surface to be excavated Definition of excavation Excavation: refer to the process of removing earth to form a the trench in the ground Or digging a hole or channel in the ground. Delimit: to mark or fix the limit. Setting out foundation and pegging Foundation :A foundation is the base on which a building rests. Its purpose is to safely transfer the load of a building to a suitable subsoil, evenly and without undue settlement. Pegging: the process of driving or inserting pegs into the ground while setting out. (See setting out procedures in previous topic).

3.2. Dig out foundation trench You may need to dig even deeper into the subsoil to excavate trenches for strip foundations. The depth of the excavation will be shown on the working drawings.

Excavation by hand using spades, hoes, wheelbarrow, pick and shovels is a good method for excavating trenches for foundations for small buildings. If you want to achieve more speed then you can use machines like back actor.

3.2.1. Theory of the angle of repose Angle of repose: refer to the maximum slope measured from horizontal at which loose solid materials will remain in place without sliding. All excavation over 1.2m deep must be sloped for avoiding the sliding materials fall from excavated trench. One method of ensuring the safety and health of workers in trench is to slope the sides of the cut to the angle of repose. Angle of repose varies with the different kind of the soil, it varies from 00 up to 900

Typical angles of repose

3.2.3. Timbering: Supporting the sides of an excavation When the depth of trench is large, or when the sub-soil is loose, the sides of the trench may cave in. The problem can be solved by adopting a suitable method of timbering. Timbering of trenches, Sometimes also known as shoring consists of providing timber planks or boards and struts to give temporary support to the sides of the trench. Methods Adopted for Timbering of Foundation Trenches: The methods adopted for timbering in consideration of depth of the trench and nature of soil areas are: 1. Stay bracing. 2. Box sheeting 3. Vertical sheeting 4. Runner system 5. Sheet piling. 1. Stay bracing: This method is used in case of supporting sides of Trenches excavated in fairly firm soil and when the depth of excavation does not exceed 2.0 m.

FIG. STAY BRACING 2. Box sheeting. This method is adopted in loose soils, when the depth of excavation does not exceed 4 metres.

Fig. BOX SHEETING

3. Vertical sheeting. This system is adopted for deep trenches (upto 10 m depth) in soft ground. The method is similar to the box sheeting except that the excavation is carried out in stages and at the end of each stage, an offset is provided, so that the width of the trench goes on decreasing as the depth increases.

4. Runner system. This system is used in extremely loose and soft ground, which needs immediate Support as excavation progresses. The system is similar to vertical sheeting of box system, except That in the place of vertical sheeting, runners, made of long thick wooden sheets or planks with iron Shoe at the ends, are provided. Wales and struts are provided as usual . These runners are driven about 30 cm in advance of the progress of the work, by hammering

5. Sheet piling. This method is adopted when (i) soil to be excavated is soft or loose (ii) depth of excavation is large (iii) width of trench is also large and (iv) there is sub-soil water. Sheet piles are designed to resist lateral earth pressure. These are driven in the ground by mechanical means (pile driving equipment). They can be used for excavating to a very large depth.’

3.2.4 Safety precautions Generals trenching and excavation rules

 Keep heavy equipment away from trench  Keep surcharge loads at least 0.6m from trench edges  Test for low oxygen hazardous fumes and toxic gases when works are more than 1.5m.  Inspect the trench at the start of each shift.  Do not work under suspended or raised loads and materials 3.3 separate top soil and refill soil.

 Remove top soil Removing top soil involved the removal of the exposed layer of the earth surface, including any vegetation or decaying much could make soil unsuitable for bearing structure load. *bearing of soil is the ability of the soil to support structural loads.

 Refill soil Use of strength soil for filling

3.4 make smooth sides and level base The sides of trench should be smooth for avoiding irregularity materials falling from excavated trench.

 Checking depth and surface level with a builder's level  Impact of levelling trench bases and making smooth sides:  Fasten foundation works  Provide structural stability to foundation  Avoid mortar wastage

EXERCISES

LU1: Clear the site

LO 1.1: Assess the site condition

1. Match the elements of column A with that of column B by writing the corresponding letter in the provided space.

Answer Column A Column B

1……….. 1. Just below the topsoil lies another layer. It is comparatively A. Natural harder and compact than topsoil. It is lighter in color than the topsoil because there is less humus in this layer.

2……… 2. Natural feature B. Masonry

3……… 3. Refers to the human-made surroundings that provide the C. Transportation setting for human activity, ranging in scale from buildings to networks parks. It has been defined as "the human-made space in which people live, work, and recreate on a day-to-day basis."

4……… 4. To clearly define the outline of the excavation and the line D. Environment of the walls and foundation, so that construction can be carried out exactly according to the plan

5……… E. Built environment 5. Element of built environment

6……… 6. It is also called humus layer, which is rich in organic material. F. Topsoil This layer consists of decomposed material and organic matter. It has dark brown color.

7……… 7. It lies just below the subsoil. It contains no organic matter and G. Building set out made up of stones and rocks, so it is very hard.

8……… 8. Where ground has previously been excavated and filled, it H. Mountains is generally necessary to dig down to a level beneath the area of the fill.

9………. 9. Surroundings made up of living and non-living items I. Subsoil

10…….. 10. Item not created by people (i.e. insects, soil, plants…) J. Type of vegetation

K. Bedrock or Parent rock

L. Filled ground

LO 1.2: Identify harmful waste to environment

Question: Answer by True or False.

1. Generally, waste could be liquid or solid waste. None of them could be hazardous. Answer:

2. Hazardous or harmful waste they are generally industrial waste and is those that potentially cause danger to public health or the environment. Answer:

3. Non-organic waste comes from plants or animals sources. They are biodegradable (this means they are easily broken down by other organisms over time and turned into manure). Answer:

4. Before the structure is set on the ground, it should be clean from all kind of waste. The removal of waste can be done manually using simple hand tools or mechanically using mechanical equipment.

Answer:

5. Standard precautions (including wearing of personal protective equipment [PPE], as applicable) should not be implemented when cleaning surfaces and facilities. Answer:

LO 1.3: Clear unnecessary trees, tree trunks and cut grasses

Question: Answer by True or False.

6. First, all vegetations such as bushes and scrub should be removed. The roots of trees and bushes must be dug out and cleared away. The site needs to be clear of rocks and boulders in the area where the building will be set out. Answer: 7. Before the site clearance is every time necessary to ask for permit in local authorities in charge. Answer: 8. Site clearance is done manually or mechanically. Answer:

9. When clearing the site only trees have to be removed. Answer:

10. Clearing the site for construction purpose is not essential, it depends on the type of the structure to be constructed. Answer:

LO 1.4: Remove the top soil

1. Match the elements of column A with that of column B by writing the corresponding letter in the provided space.

Answer Column A Column B

1……….. 1. Contains vegetation, which can damage the foundations so A. Mechanical shovels it should be removed

2……… 2. Have particles that stick together more easily. B. Top soil

3……… 3. Push the soil layer by layer to one side and pile it up nearby. C. when you remove the top They do not dig out or lift out the soil. soil,

4……… 4. Then you should have a firm subsoil that is strong enough D. Tipper truck to support the building.

5……… E. Loose soils. 5. They have particles which do not stick together and remain separate

F. Bulldozers

G. Cohesive soils

LU2: Set profile

LO 2.2: Select hand survey tools and equipment

1. Match the elements of column A with that of column B by writing the corresponding letter in the provided space.

Answer Column A Column B

1……….. 1. It is used to verify the verticality and horizontality of an A. Tape measure object/structure.

2……… 2. A tool used to verify the verticality of the structure and to B. Theodolite transfer points on the ground.

3……… 3. Is an optical instrument used to establish or verify the C. Plumb bob points in same horizontal plane.

4……… 4. Is a portable three-legged frame or stand used as platform D. Spirit level for supporting the weight and maintain the stability of a mounted object/device

5……… 5. Is a graduated wooden or aluminium rod used with a E. A level staff or levelling rod levelling instrument determine the difference in heights between points above the datum.

F. A tripod

G. Dumpy level

PRACTICAL EXERCISE

Set out the walls and foundation of 40 cm for a store room considering the following given floor plan (the dimensions are in meters).