2. INTRODUCTION Building construction, the techniques and industry involved in the assembly and erection of structures, primarily those used to provide shelter. Building construction is an ancient human activity. It began with the purely functional need for a controlled environment to moderate the effects of climate. Constructed shelters were one means by which human beings were able to adapt themselves to a wide variety of climates and become a global species.

3. SHALLOW FOUNDATIONS Spread footings Square Rectangular Circular Continuous Mat (Raft) foundations

4. SPREAD FOOTINGS Made from reinforced concrete Square (B x B)-Usually one column Rectangular (B x L)-When large M is needed Circular (D/B<3, Rounded)-Flagpoles, transmission lines Continuous (Strip)-Support of bearing walls Combined (Cantilever)-Provides necessary M to prevent failure. Desirable when load is eccentric and construction close to property line.

5. MAT (RAFT) FOUNDATIONS Necessary when the soil is weaker and more compressible Since large area is needed from a spread footing, mat foundation is more economic. Advantages Spread the load in a larger area-Increase bearing pressure Provides more structural rigidity-Reduce settlement Heavier-More resistant to uplift Distributes loads more evenly

6. DEEP FOUNDATIONS When shallow foundations cannot carry the loads Due to poor soils conditions When upper soils are subject to scour Piles-prefabricated small-size (usually < 2 ft or 0.6 m diameter or side) poles made from steel (H or pipe piles), wood or concrete and installed by a variety of methods (driving, hydraulic jacking, jetting, vibration, boring) Drilled shafts-Drilled cylindrical holes (usually > 2ft or 0.60 m in diameter) and filled with concrete and steel reinforcement

7. SHALLOW FOUNDATIONS Bearing Capacity Gross Bearing pressure q = (P+W f )/A – u where W f =  c *D*A, u = pore water pressure Net Bearing pressure = Gross Bearing pressure – Effective stress q = P/A +  c *D– u SQUARE FOOTINGS q = P/(B*b) +  c *D– u CONTINUOUS FOOTINGS

8. SHALLOW FOUNDATIONS Bearing Capacity (Cont’d) FS bearing capacity = q ultimate / q allowable = 2 to 3 q allowable = Gross bearing pressure q ultimate = cNc +  ’ D N q + 0.5  BN  strip footing q ultimate = 1.3cN c +  ’ D N q + 0.4  BN  square footing q ultimate = 1.3cN c +  ’ D N q + 0.3  BN  circular footingf See Table 17.1, page 623 for bearing capacity factors (N c, N q, N   as a function of friction angle,  c = cohesion,  ’ D = vertical effective stress at foundation base level, D (surcharge),  =unit weight of soil below foundation base level, B=width (diameter) of footing Effect of Groundwater table (Page 624) Case1- D W < D (high water table; use buoyant unit weight) Case2-D<D w <D+B (intermediate water table; prorate unit weight) Case3-D+B <D w (Deep water table; use moist unit weight )

9. SHALLOW FOUNDATIONS Design-Cohesive soils 1. End-of-construction (short term) analysis 2. Calculate q ultimate 3. q allowable = q ultimate / FS bearing capacity 4. Area allowable = P/ q allowable 5. Calculate setllement-  <  allowable- DESIGN OK  >  allowable- Consider soil improvement, deep foundation. Increasing area will not help, cause more settlement

10. SHALLOW FOUNDATIONS Design-Cohesionless soils 1. Drained (long term) analysis 2. Calculate q ultimate Assume B to calculate q ultimate 3. q allowable = q ultimate / FS bearing capacity 4. Area allowable = P/ q allowable will give you B. Iterate until B assumed = B computed 5. Check if q allowable is OK for settlement case (usually at most 1 inch)

11. Deep Foundations Design Static Analysis: Q ultimate = Q EB +Q SR (end bearing + shaft resistance) Q EB = q ult A p where A p is the area of pile tip q ult = c N c * +  ’ D N q * Q SR =  pLf where p= is the pile perimeter, L= pile length, and f = unit shaft resistance (skin friction) in a layer of soil on the side of the deep foundation f= K  ’ v tan  + c a where K=lateral earth coefficient,  ’ v = vertical effective stress at given depth,  =pile-soil interface friction angle, c a = pile-soil adhesion in a given soil adjacent to lateral pile surface Pile load test, dynamic formulas, and wave analysis during driving are also used to arrive at a reliable pile capacity, Q u. Q allowable = Q ultimate /FS ; typically FS=2 for deep foundations.

12. Bearing Capacity Factors for Deep Foundations (Meyerhof, 1976)

13. 13 Stone vs Brick Similarities: Similarities: –Both stacked –Mortar Joints Differences: Differences: – Shape: »Brick molded - Stone Cut and Carved –Physical Properties: »Brick made/controlled – Stone provided by nature

14. TYPES OF ROCKS USED IN STONE MASONRY Stone Masonry: Building stones obtained by quarrying from the rocky strata of earth and reducing it to the required shapes and sizes for construction Types of rock: (i) Igneous - Formed as a result of cooling of the molten rock to solid state - It is nonporous, hard, strong and durable - Granite: Consists mainly of quartz, feldspar, mica, and other colored minerals; colors include black, gray, red, pink, brown, buff, and green - Serpentine: Main ingredient is serpentine; color ranges from olive green to greenish black, is fine grained and dense - Basalt: Color ranges from gray to black; used mainly for paving stones and retaining walls - (ii) Sedimentary : Sediments deposited by the action of water or wind gets consolidated to a rock - Sandstone: Sedimentary rock composed of sand sized grains made of silica, iron oxide and clay - Colors include gray, brown, light brown, buff, russet, red, copper, and purple - Shale: Derived from clays and silts; weak along planes and is in thin laminations - High in limestone and color varies from black to red, yellow, and blue

15. 15 Granite Non-porous, hard, strong, durable Non-porous, hard, strong, durable Color Range Color Range Surface Textures Surface Textures Sources Sources Primary Uses Primary Uses

16. 16 Polished Surface Rough Texture

17. 17 Shape Flat to Round

18. Shale: Derived from clays and silts; weak along planes and is in thin laminations - High in limestone and color varies from black to red, yellow, and blue - Limestone: Sedimentary rock composed of calcite and dolomite - Three types: oolitic, dolomitic and crystalline - Has high compressive strength - Used for building stones and for paneling - Metamorphic: Igneous or sedimentary rock transformed by heat and pressure into another rock - Marble: Recrystallized limestone, color varies from white through gray and black, red, violet, pink, yellow, and green - Presence of oxides of iron, silica, graphite, carbonaceous, matter, and mica produce these color variations TYPES OF ROCKS USED IN STONE MASONRY (Cont’d)

19. 19 Limestone & Sandstone Porous, relatively weak Porous, relatively weak Color Range Color Range Surface Textures Surface Textures Sources Sources Primary Uses Primary Uses

20. 20 Limestone with Granite

21. Quartzite: It is a variety of and stone composed of mainly granular quartz cemented by silica, color varies from brown, buff, tan, ivory, red through gray - Schist: Made of silica with smaller amounts of iron oxide and magnesium oxide - Color varies from blue, green, brown, gold, white, gray, and red - Slate: Consists mainly of clays and shales - Major ingredients are silicon dioxide, iron oxide, potassium oxide, magnesium oxide, and sometimes titanium, calcium and sulfur - Slate found in parallel layers, which enables it to be cut into thin sheets TYPES OF ROCKS USED IN STONE MASONRY

22. 22 Metamorphic Rock Marble Slate

23. 23 Marble - Exterior Application

24. 24 Slate Flooring

25. Produced by blasting or cutting - Irregular-sized stone is produced by blasting the rock, the larger pieces are cut into smaller units for use as an exterior finish, rest is crushed and sorted into various sizes as aggregates - Most of the dimensional stones used in building construction are produced by cutting large blocks in the quarry - Cut with diamond belt saws (12ft wide, 2 to 5 ft thick, and 50 ft long); rubber air bags inflated in the saw cut to break it away and then the separated rock is lowered onto prepared stone chips cushion - Thereafter it is cut into smaller sizes and transported by front-end loaders to the mill for further processing QUARRYING AND PRODUCING BUILDING STONES

26. 26 Types of Stone Fieldstone Fieldstone Rubble Stone Rubble Stone Dimension Stone Dimension Stone

27. 27 Stone Masonry Patterns Laid in Mortar Rubble (Unsquare pieces) Rubble (Unsquare pieces) Ashlar (Square Pieces) Ashlar (Square Pieces) Coursed or Random Coursed or Random Orientation Orientation

28. 28

29. Types of Stone Masonry Walls: (i) Solid masonry wall made by laying stone masonry over a prepared bed of mortar, and proceeding in a similar manner to increase the height; (ii) Composite wall made of an outer wall of large stone slabs, attached to a backing of structural frame or brick/concrete masonry wall; and (iii) Cavity wall made by two different types of masonry wall separated by a cavity, which is either insulated or empty and connected together by metal ties Laying of stone masonry blocks in a wall: (a) Rubble Masonry - Composed of unsquared pieces of stones; mason has to choose carefully each stone so that it can fit into the available space - (b) Ashlar masonry - Made of squared pieces of stones; mason has to carefully lift the heavy stones by a hoist and lower it into place - (c) Coursed stone masonry: has continuous horizontal joints - (d) Uncoursed or random masonry : Does not have defined bedding planes for the wall TYPES OF STONE MASONRY WALLS AND THEIR CONSTRUCTION

30. 30

31. 31

32. PRECAST CONCRETE MASONRY AND CONSTRUCTION OF WALLS Precast Concrete Masonry Blocks : Manufactured by vibrating a stiff concrete mixture into metal molds, immediately turning it out wet onto a rack (so that the mold can be reused immediately) at a rate of 1000 or more units per hour - Racks are cured at an accelerated rate by subjecting them to steam, either at the atmospheric pressure or for faster curing at higher pressure. After the units are steam cured, the units are dried to a specific moisture content, and bundled in wooded crates for shipping to the construction site Made in varying sizes and shapes: Standard hollow blocks - 4”x8”x16” long or 4”x8”x8” - 6”x8”x8” or 8”x8”x8”, 10”x8”x16”, or 10”x8”x8”, 12”x8”x16” or 12”x8”x8” - Other shapes: Channel bond beam, Low-web beam, Solid unit, Capping unit, A-block, H block, Header unit, Control joint unit, Single Bullnose, etc.

33. 33 Concrete Masonry Units Manufacturing Process Manufacturing Process Configurations Configurations Testing Standards Testing Standards

34. 34 Typical Shape Bond Beam Combination ‘Corner’ – Round & Square

35. 35 Spanning Concrete Block Openings Steel Lintels Steel Lintels Block Lintels - Reinforced Bond Beam Block Lintels - Reinforced Bond Beam Precast Reinforced Concrete Lintel Precast Reinforced Concrete Lintel

36. 36 Reinforcing & Anchorage Joint Reinforcing Joint Reinforcing –Ladder –Truss

37. 37 System Properties Sizes: 10 foot lengths; width should be 2” less than wall Sizes: 10 foot lengths; width should be 2” less than wall Shapes: ladder & truss Shapes: ladder & truss Configurations: Many variations Configurations: Many variations Materials: Steel with various finishes and gauges Materials: Steel with various finishes and gauges Ladder Truss

38. 38 Layout & Lead Blocks

39. 39 Installation of Mortar Bead

40. 40 Lay CMU

41. 41 Tooled Joints

42. 42 Control Joint

43. 43 Split face (colored) and Brick

44. 44 Painted CMU

45. 45 Split face, Brick, & Tile

47. Window Terminology Windows are factory assembled as complete units, often with the exterior casing in place. The basic parts are the glazing, the sash, and the frame. Glazing refers to the clear glass or plastic portions of a window. (the glass within each section may also be called a pane or light) The sash is the part that holds the glazing and the frame is the fixed part of the assembly that receives the sash.

48. Anatomy of a Window 1. Tracks 2. Screen 3. Mounting Flange 4. Exterior casing 5. Head jamb 6. Weather-stripping 7. Sash 8. Glazing 9. Muntins 10. Removable storm panel 11. Sill

49. Types of Windows Casement Have a single hinged side that swings inward or outward Outward-swinging sash does not get in the way of furniture and the wind tends to keep push outward-swinging sash against the weather- stripping making a tighter seal. Hardware consists of a rotary opener, a hinge assembly, and a sash lock.

50. Types of Windows Awning / Hopper Awning windows swing outward at t he bottom. A hopper window is similar except that the sash swings inward at the top. Both types provide protection from rain while open. Hardware includes hinges, pivots, and sash support arms.

51. Types of Windows Horizontal Sliding Resemble casement windows in appearance. However, the sashes slide horizontally in tracks or guides, located on the sill and head jamb.

52. Types of Windows Double Hung Consists of an upper and lower sash that slides up and down in channels in the side jambs. Each sash has springs or balances to hold it in any position. Some types allow the sash to be removed or pivoted for easy cleaning, painting or repair. Hardware includes one or two metal sash locks.

53. Frame & Sash Materials Any of the basic types of windows can have sashes and frames made of wood, metal, vinyl, fiberglass, or wood composites. Hybrid windows are a combination or two or more materials

54. Wood Clad-Wood Window Wood window frames and sashes should be made from a clear grade of all-heartwood stock. Species commonly used are ponderosa pine, cedar, cypress, and spruce. Some wooden windows are referred to a “wood-clad” meaning the exterior is covered or “clad” in another type of material such as vinyl or aluminum. Wood-clad windows never need to be painted.

55. Metal Made from steel or aluminum these windows are lighter and less costly than windows made from other materials. Require less maintenance than wooden windows. Available with baked on or anodized finishes. Are very common in some parts of the country and less common in other parts, especially areas where winters are cold as metal windows experience greater heat loss. Also moist interior air has a tendency to condense on metal windows. The most efficient metal windows have two piece frames separated by a thermal break. Normally installed via a nailing flange.

56. Vinyl, Fiberglass, & Composites Structural PVC Window Windows with structural PVC (polyvinyl chloride) sashes and frames are easy to maintain. The vinyl is colored all the way through and resists attack from insects. The hollow channels in these windows are insulated making them very energy efficieint.

57. Vinyl, Fiberglass, & Composites Window frames can also be made of fiberglass, which is a polyester-based material reinforced with very thin glass strands. Like vinyl, they come in hollow and insulated types. Fiberglass is stiffer and stronger than vinyl. Composite windows are made from a mixture of polymers (plastics) and wood under pressure. They have properties of solid wood but are more decay resistant.

58. Types of Glazing Low-e glazing; also called Low-Emissivity, means that the glass radiates less heat to the outdoors than regular glass. In some types a special coating is applied to one glass surface facing the air space. This can reduce energy flow by as much as 50%. Heat-absorbing glazing; contains special tints that enable it to absorb large amounts of solar energy. Gas-filled glazing; air between the glazing is replaced by a heavier gas such as argon or krypton. The heavier gas increases energy efficiency.

59. Weather-stripping The main purpose of weather-stripping around a window is to prevent air from leaking between the sash and the frame. It can be made from various flexible materials such as foam and fibrous pile. Over time it will loose its effectiveness and must be replaced… it must never be painted or stained.

60. STAIRS AND STAIRCASES

61. Tread Newel post A staircase is a stairway which serves one dwelling. The majority of staircases used in domestic construction are made from solid timber with, manufactured board such as Medium Density Fibreboard (MDF) used for the Goings and Treads. They are usually manufactured in a workshop to specified dimensions. The flights of stairs are then delivered to and installed on site prior to plastering. Hardwood stairs may not be installed until all plastering has been completed. A stairway is a series of steps with straight nosings on plan intended for use solely in connection with one dwelling.

62. Stair Function The function of a stairs is to allow easy pedestrian access from one floor level to another in safety. Stairs must be strong enough to carry weight of people, furniture and equipment. A stairway is a series of steps with straight nosing on plan intended for use solely in connection with one dwelling.

63. Private Stairway StringBaluster Handrail Balusters should have no opening of such a size as to permit the passage of a sphere of 100mm diameter. Stairs should be designed, arranged and installed to afford safety, adequate headroom and space for the passage of furniture. Stairs should be designed to provide ease and comfort, hardwood stairs are often a design feature and should be pleasing to look at. Stairs should be designed to comply with the building regulations.

64. Tread Detail Minimum Going for domestic stairs is 220mm. Maximum Rise is 220mm string and handrail. In consecutive flights of stairs, each step shall have the same rise and the same going. Handrail to be provided on both sides of stairs if width is 1.0 metres wide or more.

65. Stair Detail

66. Stair Terms Stairwell The space in which the stairs and landing are housed. Tread Upper surface of a step on which the foot is placed Riser The vertical member between two treads Step Rise plus tread Nosing The exposed edge of tread usually rounded or splayed.

67. Stair Terms Handrail Member parallel to the string and spanning between newels or fixed to the wall. Baluster Vertical infill members between string and handrail. Newel Post at bottom and top of flight supporting handrail. String Members into which the ends of treads and risers are housed and wedged. Pitch line Line connecting the nosing of all treads in one flight.

68. Stair Terms Margin Space left between edge of nosing and edge of string. Rise Vertical distance from top of one tread to top of the next. Going Horizontal distance from face of one riser to face of the next. Total going of flight Horizontal distance from face of first riser to face of trimmer (landing). Total rise of flight Vertical distance from surface of floor to surface of landing.

70. Flooring Types Soft Flooring Carpet Rugs Resilient Hard Flooring Wood Stone Tile

71. Wood - Most popular Strip Flooring Tongue and groove Nailed to sub floor Pre-finished or unfinished Random Plank Wider than strips Screwed to sub floor, covered with wood plugs Parquet Small pieces arranged in different designs Pre-finished squares for easy installation

73. Stone Marble Various colors depending on origin Verdigris (v ə r-d ə -grēs) : marbles that have a green color Limestone: most common, usually white but may have cloudy streaks Onyx: may have layers of colors or banding

74. Terrazzo formed using marble or chipped stones embedded in full concrete. artistic and very reliable best for outdoor spaces such as verandas or patios. strong but 50% chance of breakage at quarry Stone

75. Travertine: porous limestone used on floors or walls Comes from mineral springs Holes from escaping gas Holes filled with resin which may or may not be same color Stone

76. Ceramic Tile Bathrooms, kitchens, entryways Made from baked clay Durable, moisture resistant, easy to clean Can crack if not installed on even surface

77. Other Tiles Ceramic Mosaic Individual tiles mounted together to keep together and make installation easier More often on walls Mexican Made from clay Shaped by hand Dried in sun Quarry Fired Earth/Clay Warm brown to beige

78. Resilient Floor Coverings Flooring with a semi-hard surface that returns to its original shape after stress Warmer and quieter to walk on Not quite as durable Vinyl and plastic laminate

79. Resists stains, affordable Sheet Vinyl 6, 9, 12 foot sheets Rotogravure Top layer covered with clear coating Thin, tears easily Inlaid Colored chips make designs (heat, pressure) Design all the way to backing Most durable of the vinylVinyl

80. Vinyl Vinyl Tiles 12 in. X 12 in. Sticky backing Place together like a puzzle

81. Carpet Insulates against drafts Decreases noise More comforting feel Quality Pile (nap): visible surface of carpet Density: how close the tufts are made together, more important than depth Heat setting Twist Depth

82. Carpet Fibers Nylon: most popular, durable, easy to maintain, limited colors Polypropylene (olefin): –strong, –nonabsorbent, –resists stains and static, –colorfast, –cheap, –crushes easily, –limited colors, –heat sensitive 95% made of manufactured fibers

83. Carpet Fibers Cont. Polyester blend (PET) made from recycled plastics, resists stains and fading Acrylic: feels and looks like wool, low static level, resists mildew, subject to pilling

84. Carpet Fibers Cont. soft durable long lasting expensive moth sensitive shrinkage allergies hard to clean Wool:

85. Carpeting Textures / Categories Cut Pile Formal looking plush, velvet, smooth, may flatten Saxony Similar to cut but yarns have been twisted more giving less formal appearance Frieze Informal, curly texture, shows minimal marks

86. Carpeting Textures / Categories Level Loop Loops are all same height, may have flecks of darker color, durable Multi-level Loop Two or three loop heights, sculpted or embossed effect, good in high traffic areas Cut and Loop Pile Sculptured effect from some looks cut and some braided, very durable

87. Backing or Cushion Extends life of carpet Shock absorber Less than ½” thick

88. ROOFS

89. ROOF GENERAL FUNCTION: To give a protective covering to the building, so rain, wind or snow may not damage the building Functional requirements 1.Weather resistance 2.Structural stability 3.Provide good appearance 4.Provide thermal insulation

90. Functional Requirements (cont’d) Weather Resistance 1. Required to protect a building from the damaging effects of rain & wind 2. The ingress of rain: causes damage to decorations & structural damage to timber due to attacks by fungus & insects 3. The roof is covered by a layer of impermeable material which prevents the passage of rain into a building 4. The deflection of building may be cause of wind

91. Functional Requirements (cont’d) Structural Stability Provide support for the roof covering In designing a roof structure, the designer must take into consideration the span of structural members If span at joist too great will cause bending To overcome : introducing a structural element which reduces the span

92. Functional Requirements (cont’d) Provide Good Appearance 1. Might be a major visual element in the design of a building 2. The detailing of roof can significantly affect the appearance of a building

93. Functional Requirements (cont’d) Provide Thermal Insulation 1. Roof represents a large proportion of the external surface area of a building has potential for heat loss. 2. Pitched roofs are usually insulated between the ceiling joists 3. Alternative insulation might be applied between rafters 4. Flat roof insulation is usually laid above the decking, either below or above the roof covering

94. General types of roofs: Sloping Flats Shell Domes

95. SLOPING ROOF / PITCHED ROOF Sloping roof may be categorized into: Medium to high slope – 4:12 to 12:12 Low slope - up to 3:12 Sloping roofs shed water easily to eave gutters (drain/sewer). Roof height & area increase with its horizontal dimension

96. This type of roof depends on:- Area covered Materials available Type of lighting Ventilation needed inside Available appliance Type of roofDescription Shed roofSimplest type and slopes only in 1 direction. Use for smaller span Gable roofSlopes in 2 directions, commonly used Hip roofSlopes in 4 directions Gambrel roofSlopes in 2 directions, but there is a break in slope Mansard roofSlopes in 4 directions, but there is a break in slope Saw-tooth / north light roof Used in factories where light is admitted from the glazing fixed on the steep sloping sides of the roof.

98. Shed Mansard Gambrel Hip Saw tooth Gable

99. SLOPING ROOF (cont’d) Sloping roofs may have a structure of: 1. Rafters & sheathing 2. Beams, purlins & decking 3. Trusses

100. Medium & high slope roofs may be covered with shingles, tiles or sheet materials Low slope roofs require roll or continuous membrane roofing; some shingle & sheet materials may be used on 3:12 pitches The roof slope also affects the design loads. Slope roof planes may be combined to form a variety of roof forms SLOPING ROOF (cont’d)

101. FLAT ROOFS Pitch from 0 to 10 degree Slope may be achieved by sloping the structural members or by tapering the deck or rigid insulation Slope usually leads to interior drains; perimeter scuppers can be used as overflow drains

102. FLAT ROOFS (cont’d) Roof structure may consist of:- 1. Joist & sheathing 2. Beams & decking 3. Flat trusses 4. Concrete slabs Flat roofs require continuous membrane roofing Deck

103. Shell Roof A thin shell is defined as a shell with a thickness which is small compared to its other dimensions and in which deformations are not large compared to thickness These elements are typically curved and are assembled to large structures. Example: factories and roof structures in some buildings. Advantage in construction : a lot of material is saved as the section needed is very thin.

104. Domes A roof of semi-spherical or semi elliptical shape Constructed of stone or brick or concrete, & supported on circular or regular polygon shaped walls The structure is such that within certain height & diameter ratios, very small thickness is needed

105. Common Term Used TermDescription Ridge pieceA member which runs horizontally at the highest level of the roof HipExternal angle of a sloping roof at which the roof slopes are turned down Common rafterMembers supporting the battens or boardings under the roof covering Hip rafterMembers which form the hip of the roof & to which the common rafters are attached Ridge

106. Common Term Used (cont’d) RidgeApex line of a sloping roof EavesThe lower edges of the sloping surface of a roof Eave-boardWooden board fixed along the eaves connecting the common rafters GableWall which follows the slope of the roof from eave to ridge & covers the end of a roof Barge board Wooden planks used to fix the ends of common rafters projecting beyond the sloping top of a gable wall

107. Common Term Used (cont’d) ValleyA depression formed at the intersection of two sloping roofs at their junction Jack rafterShort lengths of rafters fixed at the hip rafters & eaves board Valley rafterMember at the intersection of 2 inverted slopes to which rafters are fixed Dragon beamShort member of wood which carries the foot of a hip rafter which is attached to the tie fixed across the angle formed by the intersection of 2 wall plates at the corner of a building PurlinsMembers that laid horizontally to support the common rafters. They transmit the loads to the trusses or walls

108. Common Term Used (cont’d) Purlin cleatShort piece of timber bolted to the rafters of roof truss for fixing the purlins TrussA framework of triangles

109. ROOF COVERINGS Is a materials which gives a protective surface to the roofing structure The function is only to prevent ingress or egress of heat & moisture into the building Various types of coverings depending on :- The character of the building The type of the roofing structure Local conditions, cost, etc.

110. Types of Roof Coverings 1. Thatch - is the craft of building a roof with dry vegetation such as straw, water reed, sedge, rushes, or heather. Now become choice for rustic look and more ecologically friendly roof. 2. Wood- thin, tapered pieces of wood primarily used to cover roofs and walls of buildings to protect them from the weather 3. Shingles- roof covering consisting of individual overlapping elements. Can be made of various materials such as wood, composite or ceramic. Thatch Wood

111. Tiles 4.Tiles -made of a ceramic material and is hard and brittle, poorly suited for places where tree limbs can fall on a house's roof. 5.Slates - is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash 6.Asphalt – known as bitumen, viscous liquid or semi solid form of petroleum.

112. 7. Asbestos cement sheets -known as fibre cement sheet. It is a building material in which asbestos (silicate mineral) fibres are used to reinforce thin rigid cement sheets. 8. Corrugated iron sheets- The corrugations increase the bending strength of the sheet. Normally each sheet is manufactured longer in its strong direction. 9.Bituminous felt- bitumen mixed with a filler component such as limestone or sand or polymers to gives rigidity and tear resistance. 10.Sheet metal roof coverings (copper, zink, etc.)- roofing system made from metal piece, or tiles. Asbestos

113. ROOF DESIGN & CONSTRUCTION FACTORS Roof structure must be designed to carry: Dead loads – roof structure, deck, insulation, roofing & any equipment located on top of or suspended from roof Live loads – accumulated rain, snow & ice & traffic if any. Wind loads – pressure or suction from wind Type of roofing required against: Surface water from the outside Water vapor diffusion from the inside Moist air flow Heat flow & solar radiation