Building Bye-Laws and Standard Dimensions of Building units

What are Building Bye Law:-

Building Bye-Laws are the restriction laid down by municipal, urban development authorities and other government department a town planning trusts related to clear space to be left around the building, permissible construction area, etc hence the proposed plan of building is to be prepared accirding to the bye law which is checked and approved by above authorities

Following are Building Bye-Laws and the Standard dimensions for various building units

1) In order to be free from weathering effects and for better stability, the minimum depth of foundation is kept 1m below the ground level. The width of the foundation should be such that the stress on the soil is within its safe bearing capacity.

2) Plinth height may be 300 mm to 600 mm but 450 mm is more common. For waterlogging prone and important buildings, the minimum plinth height is 600 mm. With greater plinth height, the building gets a majestic appearance.

Building Bye-Laws

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3) Plinth area should be a minimum of 1.2 times the floor area of the building. Minimum width of the footing is 100 m more than the one above and a minimum depth of footing is the depth of the standard brick 100 mm. When a number of footings are to be provided preferably their depths are kept equal. The width of the cement concrete bed of foundation = width of the brick footing immediately above the concrete bed + 100 mm + 100 mm. (i.e. 100 mm is the minimum offset for concrete bed).

Building Bye-Laws

4) Minimum width of footing = 2t + 2j

Where, t = Thickness of wall immediately above basement level (Not less than 200 mm )

            j = offset of concrete (Not less than 100 mm)

5 ) Thickness of the damp proof courses 20 mm to 25 mm.

6 ) Thickness of cement concrete floor is a minimum of100 mm plus floor finish over it. Floor finishes are generally with 10 mm to 20 mm thick cement mortar or tiles.

7 ) Ceiling height (i.e., headroom) for main rooms of the residential building should be 3000 mm to 3600 mm. For bath and W.C. the ceiling height may be 2000 mm to 2750 mm.

8 ) The carpet area should be 50 to 65% of the floor area.

Building Bye-Laws
Carpet Area

9 ) Main entrance door of a residential building should be of 1000 mm x 2100 mm in size. Other doors should have a minimum width of 900 mm and a height of 2000 mm. Doors for the garage are 2500 mm x 2300 mm and for W.C. and bathrooms are 600 mm to 750 mm x 1800 mm with the single-leaf shutter.

10 ) The size of windows depends on the total area of window openings required.

Building Bye-Laws

Window Egress

 The following guidelines should be kept in mind:

(i) Window width = 1/8 (width of room + height of room).

(ii) Glass area in windows should be 10% to 20% of floor area of the room for  good lighting.

(ii) At least one sq.m. of window area should be provided for every 30 cubic meters of inside room space.

Generally, the minimum size of window is 750 mm x 1000 mm

Building Bye-Laws

(11) The minimum size of ventilator is 1000 mm x 500 mm in order to provide good ventilation for any habitable room. For bath and W.C. it should be a minimum of 450 mm x 300 mm. Its depth greater than 450 mm or otherwise privacy is lost.

12) Size of various room of residential building.

No .
Name of Room Minimum Dimension Maximum Dimension
1 Drawing Room or Living
4200 mm x 4800 mm 5800 mm x 7200 mm
2 Bed Room or Master Bed
3000 mm x 3600 mm 4200 mm x 4800 mm
3 Dining Room 3600 mm x 4200 mm 4200 mm to 4800 mm
4 Kitchen 2500 mm x 3900 mm 3000 mm x 3000 mm
5 Bath / WC Combined 1800 mm x 1800 mm 1800 mm x 2500 mm
6 Bath (Separated) 1200 mm x 1800 mm
7 W. C. (Separated)     1200 mm x 1200 mm
8 Guest Room 3000 mm x 3600 mm 3000 mm x 3000 mm

Building Bye-Laws

(13) Stairs:

Building Bye-Laws
Standard Stair Dimension

Rise in residential building = 130 mm to 190 mm.

Rise in office building = 125 mm to 150 mm.

Going – 275 mm to 350 mm for public buildings.

Going 250 mm to 300 mm for residential buildings.

For selecting rise and tread of a building, the following thumb rules are followed:

T 2 X R = 550 to 650

T x R = 39000 to 48000

Width of steps is 900 mm for residential buildings and is 1000 mm for public buildings.

Number of Riser = (Total Height of floor / Height of riser)

Number of treads = Number of riser – 1

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(14) Thickness of R.C.C. I lintel beam 100 mm to 250 mm and 150 mm is more common.

(15) Thickness of R.C.C. roof slab is 100 mm to 150 mm (100  mm is more common) and that of sunshades is 25 mm to 50 mm.

16) Sunshade projection through 450 mm or 500 mm beyond the facing of external wall.

RCC Lintel and Chhajja

(17) Width of verandah is from 1.8 m to 3 m and width of passage is 0.8m to 1.2 m in residential houses.

 (18) The height of parapet wall should not be less than 0.60 m and not more than 1.2 m above the finished floor level.

Parapet Wall

Building Bye-Laws

19) Height of various building component.

Sr.No. Description Height(mm)
1 Plinth Level 450 to 600 from GL
2 Window Sill Level 900 from floor level
3 Lintel Level 2100 from floor level
4 Roof Slab Level 3000 to 3600 from floor level
5 Parapet Wall 600 to 900
6 Courtyard or Garage 1500 from GL
7 Foundation for Single Story 1000 below GL
8 Foundation for Double Story 1000 to 1200 below GL
9 Railing Height 850 from thread
10 Rise of Step 150 to 190

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