BUILDING MATERIAL AND CONSTRUCTION Er Zamin Shakeel Department

BUILDING MATERIAL AND CONSTRUCTION Er. Zamin Shakeel Department of Civil Engineering SSCE, Udaipur SEMESTER-III

FLOORS SSCE DEPARTMENT OF CIVIL ENGINEERING 2

FLOORS �Floors are the horizontal elements of a building structure which divide the building into different levels for the purpose of creating more accommodation within a restricted space one above the other and provide the support for the occupants, furniture and SSCE DEPARTMENT OF CIVIL ENGINEERING 3

Floor consists of two components �SUB-FLOOR : - imparts strength and stability to support floor covering and all other super imposed loads. �FLOOR COVERING: - Covering over the sub-floor and is meant to provide clean, hard, smooth, impervious, durable and attractive surface to the floor. SSCE DEPARTMENT OF CIVIL ENGINEERING 4

SELECTION OF FLOORING MATERIAL �INITIAL COST �APPEARANCE �CLEANLINESS �DURABILITY �DAMP RESISTANCE �SOUND INSULATION SSCE DEPARTMENT OF CIVIL ENGINEERING 5

SELECTION OF FLOORING MATERIAL �THERMAL INSULATION �SMOOTHNESS �HARDNESS �FIRE RESISTANCE �MAINTENANCE COSIDERATIONS SSCE DEPARTMENT OF CIVIL ENGINEERING 6

TYPES OF FLOORS �TWO TYPES: - �GROUND FLOORS �UPPER FLOORS SSCE DEPARTMENT OF CIVIL ENGINEERING 7

GROUND FLOORS SSCE DEPARTMENT OF CIVIL ENGINEERING 8

GROUND FLOORS �The floor of building immediately on the ground is known as ground floor. �In normal construction of ground floor following two layes are constructed. � 1. 100 mm thick layer of coarse sand � 2. 100 mm thick layer of lime or cement concrete. SSCE DEPARTMENT OF CIVIL ENGINEERING 9

TYPES OF GROUND FLOORS SSCE DEPARTMENT OF CIVIL ENGINEERING 10

MUD OR MURRUM FLOORING �MUD FLOORING: - Used for unimportant buildings, particularly in villages of india. �cheap, hard, easy in construction and maintenance. SSCE DEPARTMENT OF CIVIL ENGINEERING 11

METHOD OF CONSTRUCTION � 25 cm thick layer of selected moist earth is spread and then rammed well to get consolidated thickness of 15 cm. � To prevent cracks, a small quantity of chopped straw is mixed with the moist earth. � The floors are maintained by giving occasionally a wash of cement-cow dung ( 1: 2 or 3) SSCE DEPARTMENT OF CIVIL ENGINEERING 12

Chopped straw SSCE DEPARTMENT OF CIVIL ENGINEERING 13

Chopped straw SSCE DEPARTMENT OF CIVIL ENGINEERING 14

Mud flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 15

Mud flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 16

MURUM FLOORING �Murum or disintegrated rock floors are also used in villages of india. �First of all a hard bed is prepared by laying about 25 cm think layer of rubble boulders or broken hard brick bats and then wetted and rammed. �Upon this a 15 cm layer of murum , over this another 25 cm layer of murum is spread. SSCE DEPARTMENT OF CIVIL ENGINEERING 17

MURUM FLOORING � Water is sprinkled on the entire surface and rammed well. � After ramming surface is saturated with water, of about 6 mm thick layer or film on the top. � The surface is then smeared or rubbed with a thick paste of cow-dung and the floor rammed for two days in the morning. � Finally, over the dry hard surface, a thick coat of cement cow dung plaster (1: 4) is applied evenly. SSCE DEPARTMENT OF CIVIL ENGINEERING 18

MERITS AND DEMERITS �MERITS: � Mud and murum floorings are cheap in initial and maintenance cost. � They provide a smooth, hard & impervious surface. � They offer good insulation against heat. � They possess sufficiently long life. SSCE DEPARTMENT OF CIVIL ENGINEERING 19

DEMERITS � For proper maintenance, the floors are required to be given a wash of cement cow dung plaster once or twice a week which is objectionable from sanitary considerations. SSCE DEPARTMENT OF CIVIL ENGINEERING 20

STONE ( FLAG STONE) FLOORING � The flooring consists of thin slabs of stones laid on concrete bedding. � The usual size of stones are 30 cm*30 cm, 45 cm*45 cm, 60 cm*60 cm and 45 cm*60 cm. � Their thickness varies from 2 cm to 4 cm. � The slab stones may be square , rectangular or oblong in shape with square edged. SSCE DEPARTMENT OF CIVIL ENGINEERING 21

STONE ( FLAG STONE) FLOORING � For the construction of stone flooring, the earthen base is levelled, compacted and watered, on the surface a layer of 10 to 15 cm thick concrete is laid and properly rammed. � Over this concrete bed or sub-grade, well dressed flag stones are laid and fixed with thin layer (2. 5 cm) of mortar. SSCE DEPARTMENT OF CIVIL ENGINEERING 22

Flag stone flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 23

Flag stone flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 24

Flag stone flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 25

Flag stone flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 26

MERITS AND DEMERITS � MERITS: � It provides a hard, durable and wear resisting floor surface. � Easy in construction and maintenance. � Very economical where stones are easily available. SSCE DEPARTMENT OF CIVIL ENGINEERING 27

DEMERITS � Doesnot give pleasing appearance. � Doesnot provide even surface perfectly. SSCE DEPARTMENT OF CIVIL ENGINEERING 28

BRICK FLOORING � Suitable for cheap construction. � The earth filling under floor is well compacted first and therafter 10 to 15 cm thick layer of lime or cement concrete is laid over the entire area of floor. � The bricks are laid on edge on 12 mm thick mortar. � The flooring should be cured for a minimum period of seven days before use. SSCE DEPARTMENT OF CIVIL ENGINEERING 29

Brick flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 30

Brick flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 31

Brick flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 32

MERITS AND DEMERITS � MERITS: � It offers a durable and sufficintly hard surface. � It provides a non-slippery and fire resistant surface. � It is cheap in initial cost as compared to cement concrete, terrazzo flooring etc. SSCE DEPARTMENT OF CIVIL ENGINEERING 33

DEMERITS � The only drawback is this flooring is that it is absorbant. SSCE DEPARTMENT OF CIVIL ENGINEERING 34

Wood or timber flooring � This type is not used much as groung floors. � Sometimes used for dancing halls, auditoriums etc. � The entire area of a building below the ground floor of timber is covered with an impervious material in order to prevent dampness. � The material can be either concrete or asphalt. SSCE DEPARTMENT OF CIVIL ENGINEERING 35

Timber flooring can be provided as: �Strip flooring: - narrow and thin strios which are joined to each other by tongue and groove joints( 6 to 10 cm in width and 2 to 2. 5 cm in thickness) �Planked flooring: - wider planks are used ( plank width is about 20 cm) SSCE DEPARTMENT OF CIVIL ENGINEERING 36

Timber flooring can be provided as: �Wood block flooring: - this consists of short but thicker wood blocks. �Parquet flooring: - this is similar to block flooring except thin(min. thickness=10 mm). SSCE DEPARTMENT OF CIVIL ENGINEERING 37

Wooden flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 38

Wooden flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 39

Concrete flooring � This is most commonly used these days in residential, commercial, instutional and public buildings. � i) prepration of sub-base: - the earth filling in plinth is consolidated thoroughly so as to ensure that no loose pockets are left in the whole area. A 10 to 15 cm thick layer of coarse sand is then spread over the whole area. SSCE DEPARTMENT OF CIVIL ENGINEERING 40

ii) Laying of base concrete � The base concrete used under floors may be cement concrete or lime concrete laid to a thickness varying from 7. 5 to 10 cm. � In case of cement concrete , the mix commonly used is 1: 5: 10. SSCE DEPARTMENT OF CIVIL ENGINEERING 41

Laying of topping � When the base concrete layer has fully set and hardened its surface is thoroughly cleaned and the entire srea is divided into rectangular or square panels by use of 4 mm thick glass strips. � The cement concrete topping consists of 1: 2: 4 SSCE DEPARTMENT OF CIVIL ENGINEERING 42

Cement concrete flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 43

MERITS AND DEMERITS � MERITS: � It is non-absorbant and thus it is useful for water stores. � It is adorable. � It is smooth and pleasing in appearance. � It is economical. SSCE DEPARTMENT OF CIVIL ENGINEERING 44

Demerits � It cannot be satisfactorily repaired by patch work. SSCE DEPARTMENT OF CIVIL ENGINEERING 45

Tiled Flooring � Tiled flooring is constructed from square, hexagonal, or other shapes made up of clay, cement concrete or terrazzo. � These are commonly used in residential flooring, offices, hospitals, schools and other public buildings. � The method of laying a tiled flooring is similar to that used for stone flooring. � The joints are well rubbed with a carborundum stone. SSCE DEPARTMENT OF CIVIL ENGINEERING 46

Tiled flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 47

Tiled flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 48

Tiled flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 49

Terrazzo Flooring � It is very decorative and has good wearing properties. The flooring is however more expensive. � It is widely used in residential buildings, hospitals, offices, schools and other public buildings. � Terrazzo is special prepared concrete surface containing cement and marble chips in proportion to 1: 2. � When surface has set, the chips are exposed by grinding operation. The sub base preparation and concrete base laying is done in the similar manner of cement concrete flooring. SSCE DEPARTMENT OF CIVIL ENGINEERING 50

Terrazzo Flooring � The top layer may have 40 mm thickness consisting of: a) 34 mm thick cement concrete layer (1: 2: 4) laid over the base concrete. b) About 6 mm thick terrazzo topping. � Concrete of the grade 1: 2: 4 is then laid in alternate panels leveled and finished to rough surface. When the surface is hardened, the terrazzo mix is laid and finished to the level surface. Additional marble chips may be added during the temping and rolling operations. So that, at least 80% of the finished surface show exposed marble chips. SSCE DEPARTMENT OF CIVIL ENGINEERING 51

Terrazzo Flooring � The surface is then floated and trowelled and left to dry for 12 to 20 hours. After that the surface is cured properly for 2 to 3 days. � The first grinding is done, preferably by machine using course grade (no. 60) carborundum stones using plenty of water. The ground surface is then scrabbed and cleaned. � Cement grout of cream like consistency, is then applied and is cured for 7 days. Then second grinding is done with carborundum stones of fine grade (no. 120). SSCE DEPARTMENT OF CIVIL ENGINEERING 52

Terrazzo Flooring � The surface is cured for 4 to 6 days and final grinding is done with carborundum stone. � The surface is thoroughly scrabbed and cleaned using plenty of water. � Wax polish is applied with the help of polishing machine to get final glossy surface. SSCE DEPARTMENT OF CIVIL ENGINEERING 53

Terrazzo flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 54

Terrazzo flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 55

Terrazzo flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 56

Marble Flooring � It is a superior type of flooring used in bathrooms and kitchens of residential building and in hospitals, sanatoriums, temples etc. where extra cleanliness is an essential requirement. � The base concrete is prepared in the same manner as that of concrete floor. � Over the base concrete, 20 mm thick bedding mortar of either 1: 4 cement-sand mix is spread under the area of each individual slab. � The marble slab is then laid over it, gently pressed with the wooden mallet and leveled. The paved area is properly cured for about a week. SSCE DEPARTMENT OF CIVIL ENGINEERING 57

Marble flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 58

Marble flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 59

Marble flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 60

Glass Flooring � This is a special purpose flooring used in circumstances where it is desired to transmit light from upper floor to lower floor and specially to admit the light at the basement from the upper floor. � Structural glass is available in the form of tiles in thickness varying from 12 to 30 mm. � Glass flooring is very costly and it is not used commonly. SSCE DEPARTMENT OF CIVIL ENGINEERING 61

Glass Flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 62

Glass flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 63

Glass flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 64

Plastic or P. V. C. flooring � It is made up of plastic material called poly-vinyl-chloride (PVC) fabricated in the form of tiles of different sizes and different color shades. � These tiles are now widely used in residential as well as non-residential building. � The tiles are laid on concrete base. � The tile is laid when the adhesive has set sufficiently; it is gently pressed with the help of 5 kg weight wooden roller and the oozing out adhesive is wiped off. SSCE DEPARTMENT OF CIVIL ENGINEERING 65

Plastic or P. V. C. flooring � The floor is washed with warm soap water before used. � It is resilient, smooth, good looking and can be easily cleaned. � It is costly and slippery and can be damaged very easily when in contact with burning object. SSCE DEPARTMENT OF CIVIL ENGINEERING 66

Plastic or P. V. C. flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 67

Rubber Flooring � It consists of sheets or tiles of rubber in variety of patterns and colors with thickness varying from 3 to 10 mm. � The sheets or tiles are fixed to concrete base or wood by means of appropriate adhesives ( epoxy-polyurethane). � Rubber flooring are resilient and sound proof, however they are costly. � They are used only in office and public buildings. SSCE DEPARTMENT OF CIVIL ENGINEERING 68

Rubber flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 69

Rubber flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 70

Rubber flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 71

Rubber flooring SSCE DEPARTMENT OF CIVIL ENGINEERING 72

Upper floors SSCE DEPARTMENT OF CIVIL ENGINEERING 73

Timber floors � Though timber floor is light in weight, but is poor in fire resistence and sound proofing qualities. � Timber floors used for upper floors are usually classified as: � Single floors or single joist timber floors. � Double joist timber floors � Framed or tripple joist timber floors. SSCE DEPARTMENT OF CIVIL ENGINEERING 74

Single joist timber floors � The floors consisting of only one set of joists called floor joists. � The floors are used for those residential buildings where spans are short and the loads are light. � These floors are adopted for a max. span of 4 m. � Joists are spaced 30 cm to 45 cm c/c. SSCE DEPARTMENT OF CIVIL ENGINEERING 75

Single joist timber floors � The width of joists are kept 5 to 8 cm. SSCE DEPARTMENT OF CIVIL ENGINEERING 76

Civil Engineering Drawing & Graphics Single joist floor system Double joist floor system SSCE DEPARTMENT OF CIVIL ENGINEERING 77

MERITS AND DEMERITS � Merits : � Single floors are easy to construct. � They require less initial cost. � Distribution of floor loads is more uniform. � Demerits: � The joists are liable to sag and crack. � If deep joists are used for large span then weight and cost of floor will increase. SSCE DEPARTMENT OF CIVIL ENGINEERING 78

Double joist timber floors � These floors are used where the span varies between 4 to 8 m. � Binders are used at suitable intervals. � Binders are spaced @ 2 to 2. 5 m c/c. � Binders are placed at shorter span. SSCE DEPARTMENT OF CIVIL ENGINEERING 79

� These floors are stiffer than single floor. � The binders throw the entire load of the floor at few points only and thus floor load is not evenly distributed. � Require additional material and labour. SSCE DEPARTMENT OF CIVIL ENGINEERING 80

Framed or triple joist timber floors � When span is more than 8 m and loads imposed are heavier, framed or triple floors are employed. � In framed floors binders are supported at regular intervals by large and heavy joists called girders. � Framed floors consists of joists, binders and girders. SSCE DEPARTMENT OF CIVIL ENGINEERING 81

Triple joist timber floor in house around great Britain in late 20 th century SSCE DEPARTMENT OF CIVIL ENGINEERING 82

Types � Stone � Floors of jack arches of brick or concrete � R. C. C slab floor � R. C. C beam and slab floor. � R. C. C ribbed floors or hollow tiled floor. SSCE DEPARTMENT OF CIVIL ENGINEERING 83

ROOFS SSCE DEPARTMENT OF CIVIL ENGINEERING 84

Introduction � It may be defined as the uppermost part of the building, provided as a structural covering, to protect the building from weather. SSCE DEPARTMENT OF CIVIL ENGINEERING 85

Requirements of a Roof � It should be durable against the adverse effects of various agencies such as wind, rain, sun etc. � It should grant the desirable insulation against sound and heat. � It should be structurally stable and sound, it should be capable of taking the loads likely to come over it. � It should be well-drained. � It should have efficient water-proofing arrangement. SSCE DEPARTMENT OF CIVIL ENGINEERING 86

Types of Roof � Pitched or Sloping Roofs � Flat Roofs or terraced Roofs SSCE DEPARTMENT OF CIVIL ENGINEERING 87

Pitched Roof �A sloping roof is known as pitched roof. � These are suitable in those areas where rainfall/ snowfall is very heavy. � Pitches are classified as: � Single roofs � Double roofs � Triple or framed roofs. SSCE DEPARTMENT OF CIVIL ENGINEERING 88

Pitched Roof: Basic Elements SPAN: - The horizontal distance between the internal faces of walls or supports is known as span or clear span. RISE: - It is the vertical distance between the top of the ridge and wall plate. PITCH: - It is the inclination of the sides of a roof to the horizontal plane. It is expressed in degrees or as a ratio of rise to span. RIDGE: -It is defined as the apex line of the sloping roof. EAVES: -The lower edge of a roof which are resting upon or projecting beyond the supporting walls are known as eave. SSCE DEPARTMENT OF CIVIL ENGINEERING 89

Pitched Roof: Basic Elements HIP: -The angle formed at the intersection of two roof slopes is known as hip. VALLEY: -When two roof surfaces meet together and form an internal angle, a valley is formed. VERGE: - The edge of a gable, running between the eaves and ridge is known as a verge. COMMON RAFTER: -These are the intermediate rafters, which give support to the roof coverings. PRINCIPAL RAFTER: - These are the inclined members of a truss. SSCE DEPARTMENT OF CIVIL ENGINEERING 90

SSCE DEPARTMENT OF CIVIL ENGINEERING 91

Pitched Roof: Basic Elements HIP RAFTER: - Which provided at the junction of two roof slopes. PURLINS: - The wooden pieces which are placed horizontally on principal rafters to carry the common rafters are known as purlins. GABLE: -The triangular upper part of a wall formed at the end of a pitched roof is known as gable. SSCE DEPARTMENT OF CIVIL ENGINEERING 92

Types of Pitched Roof A) Single Roofs: Ø Lean-to-Roof Ø Couple-close Roof Ø Collar beam Roof or Collar tie Roof B) Double or Purlin Roof C) Framed or Trussed Roof Ø King Post Roof Truss Ø Queen Post Roof Truss Ø Combination of king-post & queen-post truss Ø Mansard roof Truss SSCE DEPARTMENT OF CIVIL ENGINEERING 93

Single Roofs � In this type of roofs common rafters are provided to each slope without any intermediate support. � Such roof is used only when the span is limited to 5 m. � It is of following types: Ø Lean-to-Roof Ø Couple-close Roof Ø Collar beam Roof or Collar tie Roof SSCE DEPARTMENT OF CIVIL ENGINEERING 94

Lean-to-Roof � It is the simplest form of a pitched roof and it is known as pent roof. � In this type of roof, one wall is carried up sufficiently higher than the other to give necessary slope to the roof. � A lean-to roof is generally used for sheds, out-houses attached to main buildings verandah etc. � This is suitable for a maximum span of 2. 4 m. . SSCE DEPARTMENT OF CIVIL ENGINEERING 95

Lean-to-Roof SSCE DEPARTMENT OF CIVIL ENGINEERING 96

Couple Roof � This type of roof is formed by couple or pair of rafters which slope to both the sides of the ridge of the roof. � In this type of roof the common rafters slope upwards from the opposite walls and they meet on a ridge piece in the middle as shown in the fig. � A couple roof is suitable for spans up to about 3. 6 m. SSCE DEPARTMENT OF CIVIL ENGINEERING 97

Couple Roof SSCE DEPARTMENT OF CIVIL ENGINEERING 98

Couple Close Roof � This roof is just similar to couple roof except that the ends of the couple of the common rafters is connected by horizontal member, called tie beam. � The tie beam prevents the tendency of rafters to spread out and thus danger of overturning of the walls is avoided. � The tie beam may be a wooden member or a steel rod. � This roof can be adopted economically up to the span of 4. 2 m. SSCE DEPARTMENT OF CIVIL ENGINEERING 99

Couple Close Roof SSCE DEPARTMENT OF CIVIL ENGINEERING 10 0

Collar Beam Roof � When the span increases or when the load is more the rafters of the couple close roof have the tendency to bend. � This is avoided by raising the tie beam and fixing it at one-third to one-half of the vertical height from the wall plate to the ridge. This raised beam is known as collar beam. � This beam roof is adopted to economise the space and to increase the height of a room. � This roof can be adopted up to a maximum span of 4. 8 m. SSCE DEPARTMENT OF CIVIL ENGINEERING 10 1

Collar Beam Roof SSCE DEPARTMENT OF CIVIL ENGINEERING 10 2

Double or Purlin roofs � When the span exceeds 2. 4 m, the necessary size for the rafters becomes uneconomical. � Hence in order to reduce the size of rafters, intermediate supports called purlins are introduced under the rafters as shown in fig. � This roof can be adopted economically up to 4. 8 m. SSCE DEPARTMENT OF CIVIL ENGINEERING 10 3

Double or Purlin roofs SSCE DEPARTMENT OF CIVIL ENGINEERING 10 4

Framed or Trussed Roof � When the span exceeds 5 m and when there are no inside supporting walls or partitions for purlins, framed structure known as trusses are on the roof, position of cross walls, span and material of the truss. � The spacing is 3 m for wooden trusses. � Trusses carry the ridge piece and purlins on which the common rafters rest. SSCE DEPARTMENT OF CIVIL ENGINEERING 10 5

King Post Truss � In this type of truss, the central post known as king-post forms support for the tie beam. � The inclined members, known as struts, prevents the principal rafters from bending in the middle. � A king-post truss suitable for roofs of span varying from 5 to 8 m as shown in fig. SSCE DEPARTMENT OF CIVIL ENGINEERING 10 6

King Post Truss SSCE DEPARTMENT OF CIVIL ENGINEERING 10 7

Queen post truss � This truss is differ from a king-post truss in having two vertical members known as queen posts. � The upper ends of the queen posts are kept in position by means of a horizontal member known as straining beam. � Additional purlins are supported on the queen posts. � A queen post truss is suitable for roof spans varying 8 to 12 m as shown in the fig below SSCE DEPARTMENT OF CIVIL ENGINEERING 10 8

Queen post truss SSCE DEPARTMENT OF CIVIL ENGINEERING 10 9

Mansard Truss � This is a combination of king post and queen post trusses. � Lower queen post & upper king post trusses. � Use of mansard trusses results in the economy of space and room may be provided in the room as shown in the figure. SSCE DEPARTMENT OF CIVIL ENGINEERING 11 0

Mansard Truss SSCE DEPARTMENT OF CIVIL ENGINEERING 11 1

Steel Truss � For spans greater 12 m, it becomes economical to use steel trusses. � For smaller spans, steel trusses consists of angles riveted or welded together through plates known as gusset plates. � As steel resists both compression and tension stresses, the design of steel truss is simplified various types of steel trusses are shown in Fig. SSCE DEPARTMENT OF CIVIL ENGINEERING 11 2

Steel Truss Compound Fink Truss (20 to 30 m) SSCE DEPARTMENT OF CIVIL ENGINEERING 11 3

Composite truss � This truss composed of wooden members and steel. Steel members resists tension. A composite truss is light and economical as shown below. SSCE DEPARTMENT OF CIVIL ENGINEERING 11 4

Roof Covering for Pitched Roof � Roof covering is an essential part of pitches roof , to be placed over the roof frame work. � It protect from rain, snow, sun, wind & other atmospheric agencies. � Selection of roofing materials depends upon: a) Type of framework b) Initial cost c) Maintenance requirement d) Appearance e) Durability f) Availability g) Climate SSCE DEPARTMENT OF CIVIL ENGINEERING 11 5

Roof Covering Materials � Following a) b) c) d) e) f) are the roof covering materials Thatch Covering Wood Shingles Tiles Asbestos cement sheets Galvanized corrugated iron sheets Light weight roofing SSCE DEPARTMENT OF CIVIL ENGINEERING 11 6

Thatch Covering This is the cheapest roof covering, commonly used in villages. � It is very light, but is highly combustible. � It is unstable against high winds. It absorbs moisture & liable to decay. � The framework to support thatch consists of round bamboo rafters spaced 20 to 30 cm apart & tied with split bamboos laid at right angles to the rafters. � In order to drain roof effectively a minimum slope of 450 is kept. � The thickness of thatch covering should at least be 15 cm, normal thickness varies from 20 to 30 cm. � SSCE DEPARTMENT OF CIVIL ENGINEERING 11 7

Thatch Covering SSCE DEPARTMENT OF CIVIL ENGINEERING 11 8

Thatch Covering SSCE DEPARTMENT OF CIVIL ENGINEERING 11 9

Wood Shingles � It’s use is restricted to hilly areas where local timber is easily available at low cost. � Though it is light weight, it is not fire & termite resistant. � It is obtained from well seasoned timber. � They are obtained in lengths varying from 30 to 40 cm & widths varying 6 to 25 cm. � They are approximately 10 mm thick at the tail or butt end and taper to 3 mm. SSCE DEPARTMENT OF CIVIL ENGINEERING 12 0

Wood Shingles SSCE DEPARTMENT OF CIVIL ENGINEERING 12 1

Tiles � It is the oldest type of roof covering materials & is still preferred for residential building and country houses. � This is because country tiles are manufactured from locally available earth. � Following are the various types of tiles generally used: A) Plain tiles B) Curved tiles C) Italian or Allahabad tiles D) Interlocking tiles E) Spanish tiles SSCE DEPARTMENT OF CIVIL ENGINEERING 12 2

Plain Tiles � Plain tiles are made of clay or concrete, though clay are more common. � Plain or flat tiles are manufactured in rectangular shapes, of sizes varying form 25 cm X 15 cm to 28 cm X 18 cm, with thickness from 9 mm to 15 mm. � The tiles are not perfectly flat, but have slight camber of 5 to 10 mm in their length. � Before laying the tiles, common rafters are laid at 20 to 30 cm spacing. � Battens are then fixed across the rafters at a spacing 4 to 6 cm. SSCE DEPARTMENT OF CIVIL ENGINEERING 12 3

Plain Tiles SSCE DEPARTMENT OF CIVIL ENGINEERING 12 4

Plain Tiles SSCE DEPARTMENT OF CIVIL ENGINEERING 12 5

Curved or Pan tiles � Pan tiles are 33 to 36 cm long, 22. 5 to 25 cm wide and 12 to 19 mm thick. � They are flat longitudinally, but are curved transversely to a flat wave or Scurve. SSCE DEPARTMENT OF CIVIL ENGINEERING 12 6

Curved or Pan tiles SSCE DEPARTMENT OF CIVIL ENGINEERING 12 7

Spanish Tiles � This tiles are commonly used in villages. � These tiles are laid in pairs of under-tiles and over-tiles. � The under-tiles are laid with concave surface upwards while the over-tiles are laid with convex surface upwards. SSCE DEPARTMENT OF CIVIL ENGINEERING 12 8

Spanish Tiles SSCE DEPARTMENT OF CIVIL ENGINEERING 12 9

Italian or Allahabad Tiles � These tiles are also used in pairs- flat broad bottom under-tile which alternate with convex curved over-tile. � The under-tile is flat, tapered with upturned edges or flanges at the sides. SSCE DEPARTMENT OF CIVIL ENGINEERING 13 0

Italian or Allahabad Tiles SSCE DEPARTMENT OF CIVIL ENGINEERING 13 1

Inter-locking Tiles � These tiles are available with patent locking devices, the object of which is to prevent their dislodgment even in most exposed condition. � These tiles are machine made. SSCE DEPARTMENT OF CIVIL ENGINEERING 13 2

Inter-locking Tiles SSCE DEPARTMENT OF CIVIL ENGINEERING 13 3

Asbestos Cement sheets � These sheets are manufactured from asbestos fiber (@ 15%) & Portland cement. � These sheets are now becoming popular for industrial buildings, factories, sheds, auditorium & even residential building. � They are cheap, light weight, tough, durable, water tight, fire-resisting. � The main advantage is that they are available in bigger units, hence supporting frame is also cheaper, easier and lighter. � These sheets do not require any protective paint. � Construction with A. C. sheets are very fast. SSCE DEPARTMENT OF CIVIL ENGINEERING 13 4

Asbestos Cement sheets � Following points should be noted while fixing A. C. sheets: � The A. C. sheets should be laid with smooth side upward. � End lap and side lap should be properly maintained. General end lap is 15 cm but this can be varied to suit purlin spacing. � Purlin spacing and length of sheets should be properly checked before linked. � The holes for fixing accessories should be drilled (not punched) in the crown of the corrugations. The diameter of the holes should be 3 mm greater than the diameter of the fixing bolt or screw. Thus 8 mm dia. drilled holes and screwed lightly. SSCE DEPARTMENT OF CIVIL ENGINEERING 13 5

SSCE DEPARTMENT OF CIVIL ENGINEERING 13 6

Asbestos Cement sheets � Bitumen washers should be provided under G. I. flat washer. The nuts of the screws or bolts are moderately tightened when 10 to 12 sheets have been laid. They should not be screwed very tight. � Ridge capping should be secured to the ridge purlin. � The sheets should be ‘mitred’ properly as required. � The unsupported overhang of A. C. sheets should not exceed 30 cm. SSCE DEPARTMENT OF CIVIL ENGINEERING 13 7

Asbestos Cement sheets SSCE DEPARTMENT OF CIVIL ENGINEERING 13 8

Galvanized Iron Corrugated Sheets (G. I. Sheets) � G. I. sheets are also widely used. � They are stronger than A. C. Sheets. � Due to higher cost, they are replaced by A. C. sheets. � They are not used for slopes flatter than 1 in 4. � G. I. sheets are made from iron sheets which are galvanized with zinc to protect them from rusting action of water & wet weather. � These sheets are fixed in a manner similar to A. C. sheets. SSCE DEPARTMENT OF CIVIL ENGINEERING 13 9

Light Weight Roofing � The wide span industrial structures, it is desirable to reduce the weight of roof , so that structural framing can be economical. � The light weight roofing materials are of two types: A) Sheeting: i) Aluminum Sheet ii) Asbestos cement sheet B) Decking: i) Wood Wool ii) Straw board iii) Aluminum alloy and Steel decking SSCE DEPARTMENT OF CIVIL ENGINEERING 14 0

Wood Wool � It is made from wood fibres interwoven together & cement bonded under pressure in mould. � They are available in the form of slabs, having thickness 12 to 100 mm, 0. 6 m width & up to 3. 9 m length. � It has good sound absorbing & thermal insulation properties. SSCE DEPARTMENT OF CIVIL ENGINEERING 14 1

WOOD WOOL SSCE DEPARTMENT OF CIVIL ENGINEERING 14 2

Wood Wool SSCE DEPARTMENT OF CIVIL ENGINEERING 14 3

STRAW BOARD SSCE DEPARTMENT OF CIVIL ENGINEERING 14 4

� The sections comprising of a steel truss are readily available in the required dimensions, resulting in minimum wastage of material. � Steel trusses are light in weight and can be fabricated in any shape depending upon structural and architectural requirements. advantages OF Steel trusses over � Steel trusses are stronger and more rigid in comparison timber to timber trusses. The members trusses. are equally strong in tension as well as in compression. � Steel trusses can be used over any span, while timber trusses are suitable only up to 15 m span. SSCE DEPARTMENT OF CIVIL ENGINEERING 14 5

� Steel trusses are fire proof. � Steel trusses are termite proof. � Steel trusses are most resistant to othe advantages OF Steel trusses over � The fabrication of steel trusses is easier timber trusses and quicker since the sections can be machined and shaped in the workshop and then transported to the construction site for erection. SSCE DEPARTMENT OF CIVIL ENGINEERING 14 6

Flat Roof �A roof which is nearly flat is known as flat roof. � It should be noted that no roof can be laid perfectly level. � The roof must slope in one direction or the other to cause rain water to flow off rapidly and easily. � The construction of flat roof is same as that of floors except that the top surface is made slightly sloping in case of flat roofs. SSCE DEPARTMENT OF CIVIL ENGINEERING 14 7

Advantages of Flat Roofs � The roof can be used as terrace for playing, gardening, sleeping and for celebrating functions. � Construction and maintenance is easier. � They can be easily made fireproof in comparison to pitched roof. � They avoid the enclosure of the triangular space. Due to this, the architectural appearance of the building is very much improved. � Flat roofs have better insulating properties. SSCE DEPARTMENT OF CIVIL ENGINEERING 14 8

Advantages of Flat Roofs � They require lesser area of roofing material than pitched roofs. � They are more stable against high winds. � They do not require false ceiling, which is essential in pitched roof. � Flat roofs are proved to be overall economic. � In multistoried buildings, the flat roof is only choice. Since overhead water tanks and other services are located on the terrace. � The construction of upper floors can be easily done over flat roofs, if so required in future. SSCE DEPARTMENT OF CIVIL ENGINEERING 14 9

Disadvantages of Flat Roofs � They are vulnerable to heavy temperature variations, specially in tropics, due to which cracks are developed on the surface. These cracks may lead to water penetration latter, if not repaired in time. � It is difficult to locate and rectify leak in flat roof. � The speed of flat roof construction is much slower than the pitched roof. � The initial cost of flat roof is more than pitched roof. � The flat roofs exposes the entire building to the weather agencies, while the projecting elements of pitched roofs provide some protection to the building. SSCE DEPARTMENT OF CIVIL ENGINEERING 15 0

Disadvantages of Flat Roofs � The span of flat roof is restricted, unless intermediate columns are introduced. Pitched roofs can be used over large spans without any intermediate column. � The self weight of flat roof is very high. Due to this the sizes of beams, columns, foundations and other structural members are heavy. � They are unsuitable at the places of heavy rainfall. � They are highly unsuitable to hilly areas or other areas where there is heavy snowfall. SSCE DEPARTMENT OF CIVIL ENGINEERING 15 1