ENGLISH BONDIn this type of bonding, the wall is constructed using alternative courses of header andstretcher bricks. This is the most commonly used type of bonding.

FLEMISH BONDIn this type of bonding, each course has alternate header and stretcher bricks. If the wallsare not to be plastered, this type of bond can be preferred over English bond as this givesa more pleasing pattern in the elevation. Further, since the sizes of the bricks are quiteuneven at times, the header bricks can be aligned with the inner side of the wall and patchpointing can be done on the outer faces of these header bricks. Even this gives a quitepleasing pattern from outside while inner plaster is minimised or can be avoided as perneed.

Figure 3.7 Double Flemish bond

Finish top and bottom with header Finish top and bottom with headers

Figure 3 9 English garden wail bond

Bonding of

two typical course

with three stretchersand one header

Figure 3.10 Flemish garden wall bond

Figure 3.12b Angles and curves in double Flemish bond

RAT TRAP BOND

What is Rat Trap bond masonry

Rat trap bond masonry is a cost effective application of brick masonry that has beenpopularised in India by the Architect Laurie Baker in the last 20-30 years. In rat trap wall,the bricks are placed on edge, thereby leaving a cavity of 4" between the two leaves incase of a 10" thk wall. The bricks are placed alternate headers and stretchers as inFlemish bond. The rate trap masonry reduces cost by reducing the consumption of bricksand cement mortar for the same cubic meter of brickwork.

Where to use Rat Trap Bonded brick masonry ?

if the available in a place where bricks have a compressive strength of more than 35 kgper square centimetres and the other properties as per IS 1905-1987.

Advantages• Compared to a 10" thick solid brick wall, consumption of brick is reduced by 25% in rat

trap.• Due to reduction in number of bricks, the consumption of cement mortar is also

reduced.• Stability of wall is not affected as the excess material is eliminated from around the

centre line.• Acts as a good thermal insulator due to the cavity in the wall.• Plastering of the outside face is not needed as well as inside plaster is minimised since

both surfaces are fair faced.

Limitations• Not a good sound insulator.

The rat-trap bond is a masonry technique that reduces brick and mortar consumption.Bricks are placed with a 3" cavity between two leaves of brick-on-edge. The cavityprovides for thermal insulation. (see graphic below)

BRICK ON

EDGE

HEADER

JUNCTlONS

JOINTS INRAT-TRAPBONDING

ELEVATION

1st 3rd COURSE OFFLAT BRICK PLAN

115 mm thk. WALL JUNCTION WITH RAT-TRAP BONDMASONRY

2 n d 4thCOURSE OFFLAT BRICK

END WALLS (DOORS ARCHES c/c)

COURSE 2.COURSE 1

L-JUNGTtCMJ

OPENING SUPPORTS

TYPES:1. RCC (reinforced cement concrete) lintels (good for any span)2. RBC (reinforced brick concrete) lintels (good for span upto 1.2 m)3. Arches (good for spans upto 3 m)4. Corbels (good for spans upto 1 m)

LINTELS

1. PRECAST REINFORCED CEMENT CONCRETE LINTEL

What is a Precast Reinforced Cement Concrete Lintel ?A lintel is a beam that is used for spanning openings of doors, windows etc. Precast RClintels are lintels which are cast on ground and then hoisted and placed over openings.Workmanship and strength of lintels may be significantly improved by casting and curingthem on the ground.

When to use precast RCC lintels• If they are available at the local building centre or in the market.• If the required number of lintels is high enough to establish a central production.Advantages• Saves steel and cement and is therefore economical.• Improved quality due to pre-casting.• If lintel dimensions can be standardised, large scale production will bring down cost.Limitations• Infrastructure is needed for the production of pre-cast RCC lintels.Precautions• Care should be taken while lifting the lintel up to the openings. Special care to be taken

during casting, to mark the upper and lower sides (so that during lifting and placement,the top reinforcement does not go below, and vice-versa!!)

Curriculum for Training of Barefoot Engineers, Gram Vikas

2. BRICK AND REINFORCED CEMENT CONCRETE LINTELWhat is a brick and reinforced cement concrete lintel ?This type of lintel is a small RCC beam with brick on edge as a permanent shutteringmaterial from the sides.When to use a brick and reinforced cement concrete lintel ?• If the opening is not more than 1500 mm.Advantages• Reduction of RCC consumption, hence economical. Elimination of shuttering.Limitations• Not suitable for openings larger than 1500 mm.• The door and window frames should be fitted in position before the lintel work starts,

hence it needs proper co-ordination.

LINTEL AND SUN SHADE

ARCHESWhat is an arch ?Arches are an economical and aesthetic means of spanning openings. An arch is definedas an arrangement of small units of blocks placed side by side over openings in the form ofsome curve. The blocks support themselves by mutual pressure and the whole arch ismaintained in equilibrium by the resistance offered by the supports.When to use an arch and which type should be adopted?

Arches can be used over all types of openings and also in verandas as colonnades. It is aneconomical alternative of RCC lintels or beams.Parabolic arches are one hundred percent compressive. The others are subjected tobending and compression. However, in rural areas, simplicity of construction should be thedeciding factor and hence flat, segmental or semi circular arches are recommendedAdvantages• They are economical due to the use of local materials like bricks.• They look aesthetically more pleasing.Limitations• Need form work

BRICK ARCHES

CAN BE FLAT

OR SEMI-CIRCULAR

OR EVEN POINTED

OR SEGMENTAL

STONE ARCHES

You do not require staging or formwork to construct a simple CORBEL ARCH

DO'S AND DON'T'S• In case of a plinth beam, the beam will go all around the building.• In case of DPC, space will be left for doors and other openings.• It is better to insert D/W frames during masonry. If not, wooden blocks should be

inserted where hold fasts are to be fixed.• Strong connections are to be provided between different materials/old and new

masonry.

• It is good to provide bed blocks in areas where concentrated load is applied (e.g.resting place of lintels, beaks, etc.)

• Pillars should be provided in 4-1/2" block, after every 10' maximum, for stability. Or, thewall should be staggered as shown.

• Headers to be provided in stone masonry.

PILLARCONGRETE.

BRICKMASONRY

M.S.FLATS/RODS

BRICK BATSUse them for under-flooring

Lay them dry without mortar in rows tight together on a rammed earth infilling then mix aheap of lime mortar and brush it all over the floor. This gives a good base for all types offlooring.

They are very useful for all sorts of curved or round walls such as for gate posts, spiralstaircases etc. If a string of vertical joints is avoided such wails are very strong and ofcourse you always need them for orthodox bonding.

PRINCIPLES OF CONSTRUCTIONBASIC PARTS OF BUILDINGSROOFING

Roofing

PRINCIPLES OF CONSTRUCTION BASIC PARTS OF BUILDINGROOFING

TOPIC ROOFING Code: PC 3c

OBJECTIVE

DURATION

PLACE

KEY WORDS

MATERIALSREQUIRED

LESSONSTRATEGY

ASSISTANCE TOTEACHER

To enable trainee to. understand basic structural requirement• techniques method of construction• identify problems• explain parts of function of building to uses

4 session

Classroom

Flat, Pitched, RCC, ACC, Filler Slab

Hand out

Lecture

Questions to assess the trainee/ training session and trainer.• How can you decide upon the roofing method for a building?• What are the different types roof according to shape?• What are the common materials used in roofing?• Describe the method of casting an RCC slab?• Describe the method of casting an ACC slab?• Describe the method of casting a filler slab?

ROOFING

1. PURPOSE

A roof is defined as the uppermost part of a building, which is constructed in the form ofa framework to give protection to the building against rain heat snow, wind, etc. A roofbasically consists of structural elements, at the top of the building, for the support ofroof coverings.

The design and choice of roof is also as important as building's foundation. The formerprotects the building from the damaging forces starting from its top and the latter takesits care from the likely damages at is bottom. Following are the requirements of a wellplanned roof:

• It should be durable against the adverse effects of various agencies suchas wind, rain, sun, etc.

• It should grant the desirable insulation against sound and heat.• It should be structurally stable and sound and it should be capable of

taking the loads likely to come over it. It should be strong enough tosupport its own weight plus what ever load -from use, high winds oraccidental impact - it might be subjected to. In many areas, this mightinclude the possibility of a serious earthquake at some point in the life of abuilding.

• It should be well-drained• It should have efficient waterproofing arrangement.• It should preferably be non-combustible, and its supporting structure

should have sufficient fire-resistance to enable the occupants to escapesafely in the event of an accidental fire.

• It should possess a high degree of durability, and not require replacementor major repairs with a short space of years.

• It should be possible to construct it within the technical competence of thelocal building industry, which may in many areas lack, any sophisticatedtools or lifting equipment and may be unfamiliar with non-traditionalmaterials.

Aspect of technicalperformanceRain protectionStructural strength

Fire resistance

Durability and maintenance

Construction

Requirement

Resist maximum shower intensityResist dead load and live/ Impact load and maximumwind loading (cyclones)Material non-combustibleSubstructure fire-resistantLimited to periodic cleaning and maintenance:More than ten years without major repairWithin capability of local building industry.

The dominating functional requirement for a roof is that it should provide adequateprotection from the climate, and for this reason, markedly different roofing types arefound in the different climatic zones. In the hot dry climates, the difference betweenday and night temperatures creates a need for roofs of high thermal mass, which canalso be used for outdoor sleeping in hot months, and consequently, flat roofs (often ofconsiderable thickness) are used. Similarly, in the warm humid climates, the highrainfall dictates the use of pitched roofs, in which high thermal insulation but lowthermal mass, are important.

2. TYPES

The choice of roofing material is one of the most crucial decisions facing the designer ofany small building in the tropics. Usually, the roof represents the largest singlecomponent of the cost of any small building. Often as high as 40 percent of the totalcost; at the same time, it presents the most complex array of technical problems forsolution. Its tends to dominate the external appearance of the building, its symbolicsignificant for the owner is commonly of great importance.

There are several kinds of roofs. Each can be made of different materials, and eachhas advantages and disadvantages, depending on the climate, the builder's budget, theavailability of materials, and the ease of construction. To make a good decision aboutthe kind of roof to be used, the builder needs to know:

• The basic roof styles; their advantages and disadvantages for the localclimate and environment;

• The kinds of materials suitable for each roof style;• How to design and build each roof style.

The roofs are classified into the following three categories:• Flat roofs• Pitched roofs• Curved roofs.

If you want to build a roof, you have to consult the following points:• Shape and dimension• Supporting structure and its material• Material of roofing• Ventilation• Draining of water

The shape and pitch depends on:• Dimension of the house• Object (living-house, community hall, factory)• Roofing materials• Climate (temperature, rainfall)• Architecture of the building and the country

2.1 Flat RoofA roof, which is nearly flat, is known as flat roof. \t should be noted that no roofcan be laid perfectly level. The roof must slope in one direction or the other tocause rain water to flow off rapidly and easily. The construction of flat roofs issame as that of floors except that the top surface is made slightly sloping in caseof flat roofs.

Reinforced concrete flat roofs are durable and with appropriate insulation andprotective covering, can perform satisfactorily in any climate region. Theproblem with reinforced concrete is the cost and scarcity of the materials in someareas, and a variety of techniques are available to reduce the amount of steeland concrete needed through pre-casting using ceramic fillers and morestructurally efficient shapes.

Advantages Of Flat Roofs:• The construction of roof is simplified.• It is easier to make a flat roof fireproof than a sloping roof.• The roof area can be utilised for roof gardens, drying yards, etc. The

terrace can conveniently be used for sleeping in hot season or forcelebration of functions.

• The construction work of upper floors can easily be started. In case of apitched roof, the entire roof is to be removed and is to be replaced by anew floor under such circumstances. It is, therefore, considered to be thebest choice for multi-storeyed buildings.

• A flat roof is more stable against high winds.• It is not necessary to enclose the triangular space in case of a flat roof

and hence, it leads to the overall improvement in the architecturalappearance of the building.

• A flat roof does not require false ceiling which is particularly desirable incase of a pitched roof.

• For multi-storeyed buildings, a flat roof is the only choice becauseoverhead water storage tanks and other services are located on theterrace.

• A flat roof is found to be overall economical than a pitched roof.

Dis-Advantages Of Flat Roofs• A flat roof cannot be used for long spans without the introduction of

intermediate pillars and beams.• Cracks are developed on the surface of the roof, when the variable in

temperature is high.• Pockets of water are formed on the surface of the roof, if slope is not

sufficient. This leads to-the leakage of the roof and it sometimes proves tobe difficult to exactly locate the position of leakage on the roof.

• At places, where rainfall is heavy, flat roofs are not desirable.• The dead weight of flat roof is considerable and hence, it proves to be

more expensive. Its initial cost is higher than a pitched roof.• . It is difficult to trace and to rectify the leakage in a flat roof.• The progress of work in a flat is slow as compared to that of a pitched

roof.• Flat roofs are generally the most difficult to build and the least suitable of

roof styles, especially in buildings wider than 4-5 m.• They tend to sag in the middle. Unless given very strong support: the

most common forms of support; wooden or reinforced concrete beams,must be heavy to be strong; as a result they are difficult to lift into place;reinforced concrete or heavy wood columns may also be used to supportflat roofs. However, columns reduce usable space inside the building.

• Flat roofs tend to hold snow or rain; this increases the weight on thebeams and walls and leads to leaks and warping;

• Flats roofs tend to lift in wind and must be securely tied to the building; inareas with severe storms, flat roofs are dangerous.

It is possible to remove all the disadvantages or inconveniences of flat roofs byemploying modern materials and methods of construction.

2.2 Pitched RoofA sloping roof is known as a pitched roof. The definitions of technical terms usedin connection with the pitched roofs are given below.

Types of pitched roofs:Pitched roofs are classified into the following three categories:• Lean to roofs• Gable roofs• Hipped roofs

2.2.1 Lean-to RoofsLean-to roofs are generally easier to support than flat roofs. They are usuallythe least expensive and the easiest style of roof to build.

Because of their pitch (angle), they shed water easily and are particularly good inwarm, rainy climates with no snow.

Lean-to roofs are slightly less subject to wind pressure than flat roofs. However,in stormy areas they must still be very securely tied down to the walls.

Lean-to roof

This is the simplest form of a pitched roof. In this type of roof, one wall is carriedup sufficiently higher than the other one to give necessary slope to the roof.Rafters are suitably secured on the wall -plates and eaves boards, battens androof covering are provided. A lean -to roof is generally used for sheds, out-houses attached to main buildings, verandahs, etc. It is suitable for a maximumspan for 2.40 metres.

2.2.3 Gable RoofsGable roofs use more materials, require more care in design, and are moreexpensive than lean-to roofs.

However, they can be built over large areas (buildings over 10 m. wide) withoutheavy beam or column supports because they are made of relatively lightmaterials and are extremely strong.

Gable roofs are much less affected by wind than flat or lean-to roofs and aretherefore better suited to areas with strong storms.

In addition, gable roofs provide excellent insulation against head and cold. Inareas with cold nights or seasons, the triangle formed by the double pitch abovethe ceiling helps hold the heat in at night. In very hot areas, gable roofs that areventilated have the opposite effect: they pass heat out of the building quickly,thus helping to keep it cool.

in general, gable roofs are the best and most adaptable style whenever they arewithin the builder's budget.

In this type of roof, the common rafters slope upwards from the opposite wallsand they meet on a ridge piece in the middle. The common rafters are firmlysecured in position at both the ends, one end being on the ridge piece and theother on the wall plate. A gable roof is suitable for spans upto about 3.60metres.

2.2.4 Hipped RoofsHipped roofs provide more protection against wind on the ends of a building thando gable roofs. But this is their only advantage over the other roof styles. Hippedroofs are harder to. design, harder to construct and use more materials than anyother roof style.

2.2.5 Components Of A Pitched Roof

1 span2 rise3 ,gable wall4 gable outlet5 apex6 ridge7 bavese pitch

9 tin beam10 king post11 rafter12 roofing battans13 wind connection (important!14 zinc-shoets (nails with

rubber washes)15 ply-wood

16 wood battens

Hose with a gutterSlope should be at least 2%

2.2.6 Pitched Roof Coverings

Sheet RoofsProfiled sheets roofs are popular in the warm, humid and upland tropical areasfor a number of reasons. They are light and easy to lay, non-combustible, andrequire less supporting structure than tiled or thatched roofs, so arecomparatively cheap; smaller roof slopes are also possible.

Corrugated Galvanized Iron SheetsThe most widely used material is still galvanized steel sheet, known asgalvanized iron or G.I. sheet, which is obtainable in a variety of lengths andwidths, and in thickness from 22 to 32 SWG (0.8-0.4 mm) with standardcorrugations at 76 mm pitch. The main defect of G.I. sheets is that they are liableto rapid corrosion in humid areas, due to the breakdown of the zinc coating. Thishappens especially rapidly in coastal areas because of the high salt content ofthe atmosphere. Climatically, G.I. sheets have a poor performance: thermalresistance is negligible, and surface reflectivity, initially poor at about 36 percent,gets worse with time and as corrosion takes place. A life of less than 5 years iscommon, though well galvanized; thicker sheets can last much longer. In spite ofthese drawbacks G.I. sheets account for a high proportion of roofing in manyurban areas.

These are used as roof covering for factories, sheds, cheap buildings, etc. Theyare sometimes covered with ordinary half-round country tiles so as to cool theinside of the building. The sheets are laid with the corrugations running downthe slope of the roof. Laps of 15 cm at the ends and of two corrugations at thesides are to be provided. These sheets are light in weight and easy to fix.

Asbestos-Cement Corrugated sheetsAsbestos-cement (AC) sheets are made from a mixture of cement and asbestosfibres. A variety of profiles can easily be formed including deep trough profiles forextra strength and long spans. The sheets, typically of 5-mm thickness, are lightand easy to lay, and have a much better thermal performance than either steelor aluminium sheets. On the other hand, they are brittle, and thus do nottransport well. Especially over poor roads, and are liable to impact damageduring and after laying.

AC sheets have continuous corrugations. Pitch of the corrugations dependsupon the width of the sheet. Laps of 15cm at the ends and 1 to 1 1/2corrugations at the sides are to be provided. These sheets can be cut, nailed,sawn or screwed and they are light, non-absorptive, strong and tough. Thesesheets stand extreme variation of temperature and they are fast replacing otherroofing materials for the pitched roofs.

Tiled RoofsRed clay tiles are used for pitched roofs more than any material other thanthatch.

Ordinary Half-Round Country TilesThese are used for cheap buildings. If tiles are laid in two layers, the roof isknown as a double -tiled roof. An overlap of at least 80mm should be providedwhen these tiles are used. These tiles are liable to break easily and hence, theyrequire frequent replacement.

ThatchThatch is by far the most common roofing material of the humid and uplandtropical areas. The abundant and renewable supply of raw materials in theseareas, combined with its cheapness, excellent thermal properties and simplicityof construction, are the main reasons for its popularity in spite of durabilityproblems.

The normal supporting structure for any type of pitched roof in a small building ismade from timber trusses or rafters. Where sawn timber is unavailable, roundpoles of eucalyptus, poplar or other timbers can be used for bamboo trusses).Steel trusses may also be used, but tend to become economical for spans largerthan about 5 m such as industrial roofs.

Following factors should be considered before selecting the type of roof coveringfor a pitched roof:

• climate of the locality,• nature of the building,• initial cost and maintenance cost,• resistance to fire and heat, and

Thatch is a suitable material for rural buildings in humid and upland climates,combining good rain resistance with good thermal insulation; it is cheap, and theraw materials are readily available and need no processing. There are problemsof combustibility and durability; chemical treatments are available but costly; thelife of thatch is closely related to the quality of workmanship but there is ascarcity of competent thatchers in many areas.

The suitability of clay tiles for pitched roofs depends on local availability; thereare many different systems. Half-round 'country made' tiles are easily madefrom a wide variety of clays but their crude shape requires considerable overlapleading to heavy roofs. Lighter and more watertight roofs can be made withpressed tiles, but a highly plastic clay is needed. All clay tiles need a ceiling tocreate satisfactory thermal conditions. They require considerable fuel for firingand their place is gradually being taken by tiles of other-materials, especiallyconcrete, and by sheet roofs.

Sheet roofs combine lightness and ease of construction with incombustibility andare easily transportable. Metal sheets are manufactured by highly capitalintensive processes, and therefore unavailable or expensive in many countries.Asbestos cement sheets are now widely available but liable to breakage anddepend on imported fibres. Galvanized steel sheets can corrode rapidly in someenvironments. Corrugated asphaltic sheets are made from waste materials andare cheaper than other sheets where available. Fibre-reinforced cement sheetsare a promising innovation using local fibres, and suitable for on -sitemanufacture. All sheet roofs need a ceiling to achieve satisfactory insulation inall climatic regions. Supporting structures need to be precisely constructed.

2.3 Vaults And DomesThe use of tension-carrying materials such as steel or timber is needed for all theroofing solutions so far discussed. But by using the principle of the arch. A roofcan be constructed out of purely compression materials. A vault is a roof inwhich the spanning is all in one direction. Creating a sideways thrust in thatdirection at the springing point. A dome is a roof with curvature in two directions,and usually with radial symmetry, which thrusts outwards on its supports in alldirections.

Vaults and domes using stone, soil or bricks are suitable for arid climates andespecially appropriate where tension materials (timber or steel) are in shortsupply.

Curriculum for Training of Barefoot Engineers, Gram Vikas 14

3. REINFORCED CONCRETE SLABS

Reinforced concrete slab roofs can be flat or pitched. In humid areas great advantagecan be obtained from using concrete slab roofs at slopes up to 25 degrees above whichangle it becomes impossible to lay and compact the concrete adequately. Use ofstoping roofs considerably improves rainwater run-off to such en extent that the use of aseparate waterproof membrane may be replaced by a thin mortar topping applied soonafter the slab is cast; and the use of the cantilevered eaves can also provide usefulshading and water protection.A further advantage in using a pitched roof is that the slab may be designed as a'folded plate', giving strength from the rigidity of the angle at the ridge in spanningbetween the gable walls. Both thickness of slab and reinforcement can be reduced bythis, and a light weight roof results which has little thermal mass and therefore can coolquickly in the evening as required in humid.

Conventional RCC slabs require comparatively more steel andcement.

Method• In order to cast an in-situ concrete slab, a flat decking or formwork must be

assembled usually of timber.• The reinforcement is assembled on this formwork. Bars in perpendicular

directions are tied together to form a strong mesh and propped away from theformwork by concrete or spacer blocks to ensure that the reinforcement hassufficient cover of concrete to protect it form corrosion.

• The concrete is then poured round the reinforcement and up to the requireddepth and vibrated or otherwise compacted to remove trapped air.

• The surface is trowelled flat, covered and allowed to set and harden withoutdrying for a period of 7 days or more. By which time it will have gained sufficientstrength for the formwork to be removed, and the slab to carry its own weight,plus the weight of whatever covering is to be applied.

3.1 Filler SlabSince for most domestic spans, a slab of thickness at least 150 mm is required,the weight of the concrete slab itself is considerable, upwards of 0.2 tonne/m2

Strong props for the formwork are required during casting, and a considerableproportion of the reinforcement used is needed just to carry the slabs own weightsubsequently.

Much of this concrete is not used structurally, since it is in the tension zone ofthe slab, where it cracks and allows the reinforcement to carry the stress. Thus,modifications of the straight forward reinforced concrete slab are frequently usein which part of the concrete in the tension zone is replaced by cheaper lightmaterial, leaving the concrete in 'ribs' surrounding the reinforcement, and at theedge where it is needed to carry the shear force.

In a filler slab, a stack of reject tiles replaces the redundant concrete. Thissystem is particularly good because the air voids between the tiles tend toreduce the weight of the slab and also to increase its thermal insulation value,important in this warm humid climate. Whatever lightweight cellular blocks ofclay, concrete or other materials are produced, these make ideal filler forreinforced concrete slabs.

Method• Prepare wooden or steel shuttering, and apply waste engine oil on the

surface for easy de-shuttering.• Place the reinforcements with a clear cover of 15mm from the surface of

shuttering.• Prepare a dry mix of 1:2:4 cement, coarse and 20 mm down stone chips.

Add water at the rate of 25 litres per ban of cement. Do the mixingthoroughly so t h a t is homogeneous and ready for use

• Place pairs of Mangalore tiles and pour concrete in the horizontal spacebetween the tiles as well as on top. Overall thickness of the slab shouldbe 100 mm. Use hand or machine compacting method.

• Cure the slanting surfaces by placing jute bags, which will hold the waterfor some times. Water curing should be done at least five times a dayand should be continued for 10-14 days depending upon span.

When To Use Folded Filler Slab With Mangalore Tiles?It has been observed that most of the cost-effective roofs are economic up to aspan of 3.65 metres. Folded filler slab with Mangalore tiles will be economicwhen the span is greater than 3.65 metres. Generally this type of roofs isadopted in design up to a span of 6 meters, beyond which the room height willbecome too high.

Advantages. Requires less steel and cement.• Light weight structure• Good heat insulator• Attractive ceiling• Greater room height

Disadvantages• Requires shuttering materials

4. CGI/ ACC SHEET ROOFING

PRINCIPLES OF CONSTRUCTION

ASIC PARTS OF BUILDINGSDoors and Windows

DURATION

PLACE

KEY WORDS

MATERIALSREQUIRED

LESSONSTRATEGY

• Define quality, identify defects and problems,to be able to rectify problems and defects instruct andsupervise good practices

4 Session

Classroom

• Why?• What is it called?• What?

Black board, chalk pointing staff duster

SESSION 1 Showing sketches of deferent systems, with some(those used by G.V.) in detailsSESSION 2: Introduce them to terminology, show themmaterials and components in the classroom.

ASSISTANCE TO Questions to assess the trainee/ training session and trainer.TEACHER • What is the normal height of a door?

• What materials can you use for a doorframe?• Draw cut a panel door?• Describe two advantages of metal windows over wooden windows?

DOORS AND WINDOWS

To enable trainee to

TOPIC

OBJECTIVE

Code: PC 3d

PURPOSEThe main function of doors in a building is to serve as a connecting link between thevarious internal parts. Windows are generally provided to give light and ventilation both tothe Interior parts of a building. When windows are provided for the purpose of light only, "asin case of storage rooms, show rooms, etc., they may be fixed so that they cannot beopened. But when windows are provided for light and ventilation, some or all the portion ofwindows must open. This can be achieved by providing suitable hinges at top, bottom orsides.

SIZEIn general, a door should have such dimensions as will allow the movement of the largestobject likely to use the door. The widths for interior doors, external doors and doors inpublic buildings such as community centres etc. are 80 cm, 1 m and 1.20 m respectively.The total area of the window openings should be at least 15 per cent of the floor area ofthe room.

MATERIALUsual materials for doors and windows are wood, glass, plywood and metals. Wood is themost common material for doors and windows as it can be moulded in a variety of shapesand can thus present a decent appearance. Glass is used for panels to admit more light.Plywood can be used as a covering material. Metals, such as aluminium and steel, arenow commonly used, especially for windows. At places where wood is likely to be attackedby vermin, R.C.C. frames or metal frames may be provided for doors and windows.

TECHNICAL TERMSFig. 12-1 and fig. 12-2 show respectively a door and a window. The definitions of technicalterms used in connection with the doors and windows are as follows:Frame: This consists of a group of members which form a support for a door or a window.Style: This is the outside vertical member of the shutter.Top rail: This is the topmost horizontal member of the shutter.Lock rail: This is the middle horizontal member of the shutter where locking arrangementis provided.Bottom rail: This is the lowermost horizontal member of the shutter.Panel: This is the area enclosed between the rails.Holdfast: This is generally in the form of a mild steel flat bar of section 30 mm x 6 mmand of length 20 cm. Three numbers of such holdfasts are provided on each side of thedoor frame and two numbers of such holdfasts are provided on each side of the windowframe. They keep the frame in position.Horn: This is a horizontal projection of head or sill beyond the face of the frame. It isusually 15 cm or so.Shutter: The entire assembly of styles, panels and rails is known as shutter.

Sash: This is a special type of frame, made of light sections and designed to carry glass. Asash consists of two vertical styles, a top rail and a bottom rail. A sash can be dividedvertically or horizontally by providing bars. These bars are known as sash bars or glazingbars.Millon:-This is a vertical member, which is employed to sub-divide a window or a dooropening vertically.Transom: This is a horizontal member, which is employed to sub-divide a window openinghorizontally.Louver: This is a piece of timber, which is fixed in an inclined position within a frame.Putty: This is a mixture of linseed oil and whiting chalk.It is used for fixing glass panels.Architrave: This is a strip of wood, usually moulded or splayed, which is fixed around thesides and head of openings. It thus helps in giving a decent appearance to the joint offrame with the masonry. It is used only when doors and windows are placed flush with theface of masonry.

TYPES OF DOORS

LEDGED AND BRACED DOORSThese are similar to ledged doors except that diagonal members, known as braces, areprovided as shown in the figure below. The braces are generally 10 cm to 15 cm wide and30 mm thick.

FRAMED AND PANELLED DOORSThis is the most usual variety of door and it consists of a framework in which panels arefitted. The figure shows a double-leafed, framed and panelled door with four panels. Thistype of door reduces the tendency of shrinkage and presents a decent appearance. The

styles are continuous from top to bottom and rails are joined to the styles. Mullions, if any,are joined to rails. The thickness of shutter depends on various factors such as type ofwork, situation of door, number of panels, etc. But the thickness of shutter is about 30 mmto 40 mm. The thickness of panels is about 20 mm. The panels are secured in position bygrooves made inside the edges of the framework. The number and size of panels dependupon the architect's design or owner's desire. But the number varies from one to six andpanels are moulded to add to the beauty of the door. For small openings, the shutters areof single leaf while double-leafed shutters are used for large openings. The figures belowshow respectively shutters for a single panel door, a door with two panels, a door withthree panels, a door with six panels and a double-leafed door with six panels.

FLUSH DOORS

Bottom Rail

Framed flush door

Vertical Ribs

Hollow Space

Enlarged section on AA

COLLAPSIBLE DOORS

Roller

A

V

Handles

Collapsible door

ROLLING STEEL DOORS

HandleLocking Arrangement

Rolling steel door

TYPES OF WINDOWS

CASEMENT WINDOWSThese are the windows, the shutters of which open like doors. The construction of acasement window is similar to door construction and it consists of a frame, styles, rails,vertical and horizontal sash bars and sometimes, it also includes mullions and transoms.The figure below shows a typical wooden casement window.

METAL WINDOWSThese are now a days widely used, especially for public buildings. Metal used in theconstruction may be mild steel, bronze or other alloys. Steel windows are manufactured instandard sizes and are widely used metal windows. The metal frame may be fixed direct tothe wall as shown in figure (A) or it may be fixed on a wooden frame as shown in the figure

Curriculum for Training of Barefoot Engineers, Gram Vikas

• . -

•

PRINCIPLES OF CONSTRUCTION BASIC PARTS OF BUILDINGS

Doors and Windows

(B). In the former case, lugs and plugs are provided to keep the frame in position. In thelatter case, screws are used to fix the metal frame with the wooden frame.

Metal window fixedto the wall

Metal window fixedon a wooden frame

Following are the advantages of steel windows over wooden windows:• Steel windows are factory made products and hence, they possess greater precision as

compared to wooden windows.• Steel windows are not subject to contraction or expansion due to weather effects as in

the case of wooden windows.• Steel windows exhibit elegant appearance.• The members of steel windows are narrow and hence, steel windows admit more light

and ventilation for the same area, as compared to wooden windows.• Steel windows are easy to maintain and their cost of maintenance is almost negligible

as compared to that of wooden windows.• Steel windows are highly fireproof and termite-proof.• Steel windows grant better facilities for providing different types of openable parts.• Steel windows are more durable and stronger as compared to wooden windows.

MOSQUITO-PROOFINGTo avoid the nuisance of mosquitoes and flies, it becomes necessary to make mosquito-proof shutters of doors, windows and ventilators. Such type of construction is very muchuseful for doors, windows and ventilators of refreshment rooms, sweet shops, kitchens,hotels, etc. The shutters of doors, windows and ventilators are made mosquito-proof asshown below.

Curriculum for Training of Barefoot Engineers, Gram Vikas

Doors

FIXTURES AND FASTENINGS FOR DOORS AND WINDOWS

Garnet hinge Parliamentary hinge Butt hince Strap hinge

Tower bolt Aldrop bolt Hook and eyeBarrel bolt

Bow handle Lever handle Pad lock Peg stay

Curriculum for Training of Barefoot Engineers, Gram Vikas

. . . . • . . .

PRINCIPLES OF CONSTRUCTIONBASIC PARTS OF BUILDINGS

Finishes

TOPIC FINISHES Code: PC 3e

OBJECTIVE

DURATION

PLACE

KEY WORDS

MATERIALSREQUIRED

To enable trainee to• Define quality, identify defects and problems,• to be able to rectify problems and defects , instruct and

supervise good practices

8 Session

Classroom

. What?

. Why?• Where?• With what? (materials)• (Not now!)

Black board, chalk pointing staff ,OHP

LESSONSTRATEGY

Session 1,2,3,4• plastering pointing, paints, distemper and whitewashSession 5,6,7,8. Flooring, Water Proofing (types, purposes, advantages

disadvantages of ail)

ASSISTANCE TO Questions to assess the trainee/ training session and trainer.TEACHER

1 What Ratio of cement and sand would you use in internal plaster?2.Which materials do you need to provide an IPS floor?3.Describe how you would make a fiat roof waterproof?

PLASTERING AND POINTING

PLASTERINGPlastering is the process of covering rough surfaces of walls, columns, ceilings and otherbuilding components with thin coat of mortars to form a smooth durable surface. Thecoating of mortar is termed as plaster.Objects of plasteringPlastering is done to achieve the following objects:• To protect the external surfaces against penetration of rainwater and other atmospheric

agencies.• To give smooth surface in which dust and dirt cannot lodge.• To give decorative effect.• To protect surfaces against vermin.• To conceal inferior materials or defective workmanship.

REQUIREMENTS OF GOOD PLASTER.The plaster material should fulfill the following requirements:• It should adhere to the background, and should remain adhered during all variations in

seasons and other atmospheric conditions.• It should be hard and durable.• It should possess good workability.• It should be possible to apply it during all weather conditions.• It should be cheap.• It should effectively check penetration of moisture.

TYPES OF MORTARS FOR PLASTERINGThe selection of type of plaster depends upon the following factors:• Availability of binding materials.• Durability requirements.• Finishing requirements.• Atmospheric conditions and variations in weather.• Location of surface (i.e. exposed surface or interior surfaces).Following types of mortars are commonly used for plastering• Lime mortar• Cement mortar• Lime cement mortar

Cement mortarCement mortar is the best mortar for external plastering work since it is practically non-absorbent. It is also preferred to lime plaster in both rooms etc, and in damp climates.

Cement mortar is much stronger than lime mortar. The mix proportion (i.e. cement:sand)may vary from 1:4 to 1:6. Sand used for plastering should be clean, coarse and angular.

VARIOUS TYPES OF MORTAR TO BE USED IN VARIOUS SITUATIONSRECOMMENDED MORTAR MIXES

Situation

1

2

3

4

External Plaster in localities whererainfall is less than 500 Mm peryear and where sub- Soil water isnot within 2.5 m Below the groundsurface:

(a) Below D.P.C.

!

(b) Above D.P.C.

External plaster in localities whererain fall is more than 1300 mm peryear and where subsoil water is notwithin 2.5m below ground surface:

(a) Below D.P.C.

(b) Above D.P.C.

External plaster in localities wherethe subsoil water is within 2.5 m ofthe ground

Below D.P.C.

Internal plaster in all localities

Composition of Mortar

1 cement 6 sand

1 cement 2 lime 9 sand

| 1 lime 2 sand

1 lime 1 sand 1 surkhi

1 lime 2 surkhi

1 cement 2 lime 9 sand

1 lime 2 sand

1 lime 1 surkhi sand

1 lime 2 surkhi

1 cement 4 sand

1 cement 1 lime 6 sand

1 lime 2 surkhi

1 cement 2 lime 9 sand

1 lime 2 sand

1 lime 1 sand 1 surkhi

1 lime 2 surkhi

1 cement 3 sand

1 lime 2 sand

1 lime 1 surkhi 1 sand

1 lime 2 surkhi

1 cement 2 lime 9 sand

I.S. Grading of Lime

-

B or C

A

B or C

B or C

B or C

A

B or C

B or C

B or C

B or C

B or C

A

B or C

B or C

-

A

B or C

B or C

B or C

Note : the ratio of lime varies with % purity of lime and these ratios may be suitably adjusted depending uponlocal practice.