Building Construction
Classification of Doors on basis of arrangement of components
· Battened and ledged Doors
· Battened, ledged and braced Doors
· Battened, ledged and Framed Doors
· Battened, ledged, braced and Framed Doors
Types of Windows
1. Fixed Window 2. Pivoted window 3. Double hung window 4. Sliding window 5. Casement window
6. Sash window 7. Louvered window 8. Metal window 9. Bay window 10. Clerestory window
11. Corner window
The Strength of Brick Masonry depends upon the following factors
(i) Type and quality of bricks (ii) Mortar mix proportion (iii) Size and shape of masonry Construction
Material Used for Damp proof course
(i) Hot Bitumen (ii) Mastic asphalt (iii) Bituminous or asphaltic felts (iv) Metal sheets (v) Combination of sheets and bituminous felts (vi) Special bricks (vii) Stones (viii) Mortar (ix) Cement Concrete (x) Plastic sheets
Requirements of Good Plaster
(i) It should adhere to the background and should remain adhere during variations in season ant atmospheric conditions (ii) It should be hard and durable (iii) It should poses good workability (iv) It should be possible to apply it during weather conditions (v) It should be cheap (vi) It should effectively check penetration of moisture
Pointing
Pointing is the finishing of mortar joints in masonry. In exposed masonry, joints are considered to be weakest and most vulnerable spots from which rain water and dampness can enter. Pointing consist of raking the joints to a depth of 20mm and filling it with better quality mortar
Mortar (i) Lime mortar 1:2 (1 lime: 2 sand or surkhi) (ii) Cement Mortar 1:3 (1 cement: 3 sand)
Preparation of surface
(i) New work: - All the joints are raked down to a depth of 20mm while the mortar is still soft. The surface and joints then cleaned and thoroughly wetted.
(ii) Old work: - All loose pointing and superfluous mortar on the surface and the joints are removed. The joints and surface cleaned and then wetted
Following are the situations in which a pile foundation is preferred
(1) The load of superstructure is very heavy and its distribution is uneven.
(2) The top soil has poor bearing capacity.
(3) Sub soil water table is high so that pumping of water from the open trenches for the shallow foundation is difficult and uneconomical.
(4) There is a large fluctuation in sub soil water level.
(5) If deep strip foundation is attempted timbering of sides of the trenches is difficult to maintain or retain the soil of sides of the trench
(6) The structure is situated on the sea, shore or river bed where there is danger of scouring action of water
(7) Canal or deep drainage lines exist near the foundation
(8) Top soil is expansive nature
Methods of improving safe bearing capacity of soils
(1.) Increasing depth of foundation (2.) Compaction of soil (3.) Drainage of soil (4.) Confining of soil (5.) Grouting( 6.) Chemical treatment
Compaction of soil (a) Ramming moist soil (b) Rubble compaction of soil (c) Flooding of soil (d) Vibration (e) Vibroflotation (f) Compaction by pre loading (g) Using sand piles
Causes of failure of foundations
1. Unequal settlement of sub soil 2. Unequal settlement of masonry 3. Sub soil moisture movement 4. Lateral pressure on walls 5. Lateral movement in the subsoil 6. Weathering of subsoil due to trees shrubs
Brick Masonry preferred over other types of masonries due to following reasons
1. All bricks are of uniform size and shape and hence they can be laid in any pattern
2. Bricks are light in weight and small in size hence the can be easily handled by brick layers by hand
3. Bricks do not need any dressing
4. The art of brick laying can be understood very easily and even unskilled mason can do the brick masonry, stone masonry construction requires highly skilled masons.
5. Bricks are easily available at all sites unlike stones which are available only at quarry sites due to they do not required transportation.
6. Ornamental work can be easily done with bricks.
7. Light partition walls and filler material walls can be easily constructed in brick masonry.
Various types of bonds provided in brick masonry
1. Stretcher bond 2. Header bond 3. English bond 4. Flemish bond 5.Facing bond 6. English cross bond 7. Brick on edge bond 8.Dutch bond 9.Raking bond 10.Zigzag bond 11.Garden wall bond
Composite masonry
Composite masonry is which is constructed out of two or more types of building units or different types of building materials. The composite masonry may be adopted due to two reasons
(i) Improvement in the appearance of walls, etc.
(ii) Use of available materials to obtain optimum economy
Composite masonry may be of the following types
1. Stone composite masonry
2. Brick stone composite masonry
3. Cement concrete masonry
4. Hollow clay tile masonry
5. Reinforced brick masonry
6. Glass block masonry
Difference between asbestos cement sheets and GI sheets
1. Asbestos cement sheets are cheaper than GI sheets
2. AC sheets are made of about 15% asbestos fiber and Portland cement whether GI sheets are made of iron sheets which are galvanized with in zinc
3. AC sheets are not used flatter than 1:4 , GI sheets may used even flat roofs
4. AC sheets are available in 1 to 3m lengths only whether GI sheet can be available at any sheet length
5. AC sheets are brittle so they need precautions while handling but GI sheets are flexible and no precautions for handling
Underpinning
The process of placing a new foundation under an existing one or strengthening an existing foundation is called underpinning of foundations. Underpinning may be required to serve the following purposes
(i) To strengthening the shallow foundation of existing building when a building with deep foundation is to be constructed adjoining it.
(ii) To strengthen existing foundation which has settled and caused cracks in the wall
(iii) To deepen the existing foundation (resting on poor strata) so as to rest it on deeper soil strata of higher bearing power.
(iv) To construct a basement in the existing building.
.
.
.
Scaffolding
When the height of wall or column or other structural member of a building exceeds about 1.5m, temporary structures are needed to support the platform over which the workmen can sit and carry on the constructions. Theses temporary structures, constructed very close to the wall, is in the form of timber or steel framework, commonly called scaffolding
Component parts
(i) Standards. these are vertical members of framework, supported on the ground or drums, of embedded into the ground.
(ii) Ledgers. These are horizontal members running parallel to the wall.
(iii) Braces. These are diagonal members fixed on standards
(iv) Putlogs. These are transverse members, placed at right angle to the wall with one end supported on the ledgers and other end on the wall.
(v) Transoms. These are those putlogs whose both ends are supported on ledgers.
(vi) Bridle. This is a member used to bridge a wall opening; workmen material; these are supported on the putlogs.
(vii) Guard rail. This is a rail, provided to like a ledger, at the working level.
(viii) Toe board. These are boards, placed parallel to ledges, and supported on putlogs, to give protection at the level of working platform.
Types of scaffolding
(i) Single scaffolding or brick-layers scaffolding.
(ii) Double scaffolding or mason scaffolding
(iii) Cantilever or needle scaffolding
(iv) Suspended scaffolding
(v) Trestle scaffolding
(vi) Steel scaffolding
(vii) Patented scaffolding
Ventilations:
Ventilation may be defined as supply of fresh outside air into an enclosed space or removal of inside air from the enclosed space. Ventilation is necessary for the following reasons
1. Creation of air movement. 2.Prevention of undue accumulation of carbon dioxide 3.Prevention of flammable concentration of gas vapour. 4.Prevention of accumulation of dust and bacteria carrying particles 5.Prevention of odour caused by decomposition of building material.6.Removal of smoke, odour and foul smell generated/librated by the occupants’. 7.Removal of body heat generated/librated by the occupants. 8. Prevention of condensation or deposition 9. Prevention of suffocation conditions in conference rooms, committee halls, cinema hall, big rooms,etc
White washing of surface of building is necessary on both hygienic and aesthetic reasons. In order to obtain a clean, neat and uniform finish ,it is necessary to adopt proper method for both preparation of surface to receive white wash and for application of white wash. White wash is prepared from fat lime. The lime is slaked at the site and mixed and stirred with about five liters of water for 1 kg of unslaked lime to make a thin cream. This should be allowed to stand for a period of 24 hours, and then should be screened through a clean coarse cloth. One kg of gum is dissolved in hot water to each m3 of lime cream. About 1.3 kg of sodium chloride dissolved in hot water may also be added to every 10 kg of lime. Sometimes rice is used in the place of gum. The application of sodium chloride (common salt) to lime-wash helps in quick carbonation of calcium hydroxide making the coating hard and rub-resistant. Small quantity of ultra marine blue (up to 3g per kg of lime) may be added to the last two coats of white wash solution.
The difference between pier foundation and pile foundation lies in the method of construction. Though pile foundation transfer the load through friction and or bearing pier foundation transfer the load only through bearing. Pier foundation is preferred in a location where the top strata consist of decomposed rock overlying strata of sound rock. In such a condition it becomes difficult to drive the bearing piles through decomposed rock. In the case of stiff clays which offer large resistance to the driving a bearing pile, pier foundation can be conveniently constructed
Brick Nogging is the term used to denote brick work built up between wooden quarters or framing. The uprights or posts are 150 mmx120mm in size, placed at a central distance of 1.50m apart. The horizontal members are ribs of planking (known as noggin members) 100mmx50mm, fixed at 900mm vertical distance apart. All the faces of the timber in contact with the masonry is well coated with boiling coal tar (two coats) and the timber exposed to view, on completion is given three coats of specified paints. The bricks are laid in the opening of the framework and placed in such a way that equal projections of timber are left on both the sides, brick work is done in lime or cement mortar. After the completion of brick work, the surface of brick work is kept thoroughly wetted before plastering. Nails are driven into the ledge on the timber frame work to give a hold to the cement /lime plaster with which both faces of the brick work is then finished off, of a thickness to be flush with the faces of the posts. The plastering is cured for three weeks. It the wooden members are of shorter width and entire exposed surface is to be plastered. This arrangement will check the plaster from peeling off from wooden member.
Advantages of flat roofs
1. The roof can be used as terrace for playing, gardening, sleeping and celebrating functions.
2. Construction and maintenance is easier.
3. They can be easily made fire proof, in comparison to pitched roof.
4. They avoid the enclosure of triangular space. Due to this the architectural appearance of the building is very much improved.
5. Flat roofs have better insulating properties
6. They required lesser area of roofing material than pitched roof.
7. They are more stable against high winds.
8. They do not require false ceiling, which is essential in pitched roofs
9. Flat roofs are provided to be overall economical.
10. In multi-storied buildings, flat roof is the only choice, since overhear water tanks and other services are located on the terrace.
11. The construction of upper floors can be easily done over flat roofs, if so required in future.
Disadvantages of flat roofs
1. The span of flat roof is restricted, unless intermediate columns are introduced. Pitched roofs can be used over large spans without any intermediate columns.
2. The self weight of flat roof is very high. Due to this the sizes of beams, columns, foundations, and other structural members are heavy.
3. They are unsuitable at places of heavy rainfall.
4. They are highly unsuitable to hilly areas or other areas where the heavy snow fall
5. 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 later, if not repaired in time.
6. It is difficult to locate and rectify leak in flat roof.
7. The speed of flat roof construction is much slower than the pitched roof.
8. The initial cost of flat roof is more than pitched roof.
9. The flat roof exposes the entire building to the weather agencies, while the projecting elements (such as eaves etc.) of pitched roof provide some protection to the building.
Anti termite treatment is done because termite damages wooden parts and furniture of building it prospers in dampness and dark. Anti termite may be divided into two categories
(i) Pre-construction treatment
(ii) Post-construction treatment
(i) Pre-construction treatment: - this treatment is started right at the initial stage of construction of building it can be divided into three operations
(a) Site preparation.
(b) Soil treatment
(c) Structural barrier.
(a) Site Preparation: - This operation consists of removal of stumps, roots, logs, waste wood and other fibrous matters from the soil at the construction site. This is essential the termites thieve on these materials. If termite mounds are detected, these should be destructed by use of insecticide solution, consisting of any one of the following chemicals:
(1.) DDT 5% (2.) BHC 0.5% (3.) Aldrin 0.25% (4.) Heptachlor 0.25% (5.) Chlordane 0.5%
Four liters of the above emulsion in water is required per cubic meter of volume of mound. Holes are made in the mound at several places by use of crow bar and the insecticide emulsion is poured in these holes
(b) Soil treatment: - The best and only reliable method to protect building against termites is to apply a chemical treatment to the soil at the time of construction of the building. This should be done in such a way that a complete chemical barrier is created between the ground from where the termites come and damage wood work in the building. An insecticide solution consists of any one of the following chemicals in water emulsion:
Aldrin 0.5% , Heptachlor 05%, Chlordane 1%
Out of the above chemical and several other chemicals, Aldex 30 EC has proved to be the most effective. It has the following advantages (i) It is highly toxic to termites. (ii) It can easily be applied after dilution with water (iii) It is insoluble in water. (iv) it is effective even many years after application
One part of aldrex 30 E.C. is diluted with 59 parts of water. This provides an emulsion of 0.5% aldrin. The emulsion should be applied evenly either with a watering cane or sprayer at the foundations and refilled earth or before lying the floor entire leveled surface is to be treated at the rate of 5 liter PER SQ M.
(c) Structural Barrier :- Continuous impenetrable physical structural barriers may be provided continuously at plinth level to prevent entry to termite through walls
(ii) Post construction treatments: - It is a maintenance treatment for those buildings are already under attack of termites. It is essential to carry out inspection to estimate the magnitude of spread of termite in the building and detect the points of entry of termites in the building. These points may be in near vicinity of columns, basement, steps, leading from ground, bathrooms and laboratories, leaking pipes, drainage etc. Whenever these shelter tubes are detected , these should be destroyed fter injecting anti termite emulsion through these.
Salient features of framed and paneled doors
1. The styles are continuous from top to bottom, i.e. they are in single piece.
2. Various rails (i.e., top rail, bottom rail and intermediate rails) are jointed to the style at both the ends.
3. The styles and the rails are jointed by tenon and mortised joints.
4. Mullions or mutinies, if provided, are jointed to the adjacent rails between which it is fixed.
5. Bottom and lock rails are made wider than top and frieze rails.
6. The entire frame is grooved on all the inside faces to receive the panels.
7. Additional timber beading is provided either on one or on both sides to improve the elevation of the door.
8. The lock rail elevation is so adjusted that its centre line is at a height of about 800 mm from the bottom of the shutter
9. The minimum width of style is kept as 100 mm. The minimum width of bottom rail and lock rail is kept as 150mm.
10. If panels are made of timber, its minimum width should be 150mm, and minimum thickness should be 15mm. However the maximum area of single panel of timber should not be more than 0.5m2. These restrictions do not apply to panels of plywood, particle board or hard board
Three coats plaster: - The following procedure is adopted
1. The background is prepared by racking the joint to a depth on 20mm cleaning the surface and well watering it.
2. If the surface to be plastered is very uneven a preliminary coat is applied to fill up the hollows, before the first coat.
3. The first coat or rendering coat of plaster is applied the thickness being equal to the specified thickness of plaster less than 2 to 3 mm. in order to maintain uniform thickness of plaster screeds are formed of plaster on wall surface by fixing dots of 15cm x15cm size. Two dots are so formed in vertical line, at a distance about 2.0 m and are plumbed by means of a plumb bob. A vertical strip of mortar, known as screed, is then formed. A number of such vertical screeds are formed at suitable spacing. Cement mortar is then applied on the surface between the successive screeds and the surface is properly finished
4. Before rendering hardens it is suitably worked out to provide mechanical key for the final or finishing coat. The rendering coat is trovelled hard forcing mortar into the joints and over the surface. The rendering coat is kept wet for at least 2 days, and then allowed to dry completely.
5. The intermediate coat known as floating coat is applied. The purpose of this coat of plaster is to bring the plaster to an even surface. The thickness of rendering coat, floating coat and finishing coat are kept 9 to 10mm, 6 to 9 mm and 2 to 3 mm respectively. The rendering coat is made rough. The finishing coat may be applied about 4 to 7 days after applying the first coat. The finishing coat may be applied about 6 hours after application of floating coat
Preparation of surface for panting for old Wood work
Before painting to old work, the old paint having cracks and blisters should be removed applying any one of the following solvent or paint removers.
1. Applying solution containing 1 kg of caustic soda in 5 liters of water. The paint gets dissolved
2. Applying mixture containing 1 part of soft soap, 2 parts of potash and 1 part of quick lime, which in hot state. After 24 hours of application the surface is washed with hot water
3. Applying mixture of equal part of washing soap and quick lime to required consistency. After one hour of application the surface is washed with water
After removing the old paint the surface is properly cleaned and then rubbed with pumice stone or glass paper.