Standard Dimensional Requirements Of Building Components


The country’s responsible authorities determine the standard dimension of all components of a building and the minimum size and other regulations to follow while designing a structure.

These norms and specifications provide adequate protection for construction workers, users’ health and comfort, and the general public.

Building bye-laws are rules of restrictions imposed by municipal, urban development authorities, or any other government authority, such as town planning trusts.

It provides the amount of construction allowed, the amount of clear space to be left around a building, and so on. So, the proposed building design must be created following the bye-law, verified, and approved by the government authorities.

This defines the building dimensions standard in residential buildings. Bye-laws are regulations that ensure the correct construction of a project while also considering safety and preventing future harm to the structure.

Dimensional Standards of Building Components

Footing, Column, Beam, Slab, Lintel, Doors, Windows, Sill, and D.P.C., filling up the earth, constructing a parapet wall, and so on are the basic components of a building structure.

These components of the structure support, enclose and protect the structure. The standard dimension of building components are discussed below:

1. Depth of Foundation

The minimum foundation depth is kept at 1 meter below ground level to avoid weathering impacts and improve stability. The foundation’s width should be such that soil stress is kept within its safe bearing capacity. When a large number of footings are necessary, the depths should be kept as equal as possible.

2. The Plinth Of Buildings

The plinth or any other component of a structure must be positioned in proportion to the surrounding ground level to allow proper site drainage.

A minimum of 450 mm must separate the plinth from the surrounding ground level. The height of the plinth can vary from 300 to 600 mm, but 450 mm is the most usual.

The minimum plinth height for water-prone and important buildings is 600 mm. The structure takes on a more majestic appearance with a higher plinth height.

The plinth area should be at least 1.2 times the floor area of the building. The minimum footing width is 100 m wider than the one above, and the minimum footing depth is the same as the standard brick depth of 100 mm.

3. The Thickness Of Damp Proof Course (D.P.C)

At the plinth level, D.P.C. is a layer of waterproofing material such as asphalt or waterproof cement. The superstructure walls are built above the D.P.C. layer to prevent moisture from rising from the ground surface to the walls.

D.P.C. is often laid to the plinth level in brick masonry construction. As a result, D.P.C. has the same width as a brick wall and thicknesses ranging from 2.5cm to 5cm.

4. The Thickness Of Cement Concrete Floor

The cement concrete floor must be at least 100 mm thick, with a floor finish applied on top. As a floor finish, cement mortar or tiles with a thickness of 10 mm to 20 mm are typically used.

5. Height Of Ceiling

The main rooms of the residential building should have a ceiling height of 3000 mm to 3600 mm (i.e., headroom).

The ceiling height for the bath and the toilet can range from 2000 to 2750 mm. (The type of structure determines the maximum height of the building.)

6. Sizes of Rooms

Sl no.Name of RoomMinimum DimensionMaximum Dimension
1.Drawing Room or Living Room4200 mm x 4800 mm5800 mm x 7200 mm
2.Bed Room or Master Bed Room3000 mm x 3600 mm4200 mm x 4800 mm
3.Dining Room3600 mm x 4200 mm4200 mm to 4800 mm
4.Kitchen2500 mm x 3900 mm3000 mm x 3000 mm
5.Bath / WC Combined1800 mm x 1800 mm1800 mm x 2500 mm
6.Bath (Separated)1200 mm x 1800 mm
7.W. C. (Separated)    1200 mm x 1200 mm
8.Guest Room3000 mm x 3600 mm3000 mm x 3000 mm

7. Sizes of Doors

A residential building’s main entrance door should measure 1000 mm by 2100 mm, and other doors must be at least 900 mm wide and 2000 mm tall.

The garage doors are 2500 mm x 2300 mm, while the single–leaf shutter doors for the W.C. and bathrooms are 600 mm to 750 mm x 1800 mm.

8. Sizes Of Windows

The Sill level is the starting point for any window in a house or a level where windows are installed. To achieve evenness in all window levels, the sill level is critical.

Any house should have a sill level of roughly 3 feet (900 mm). The size of the windows is determined by the overall area of the needed window apertures. It’s important to remember the following guidelines:

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

ii) For optimal illumination, windows should have a glass area of 10% to 20% of the room’s floor area.

iii) One square meter of window area should be provided for every 30 cubic meters of interior room space.

iv) 750 mm x 1000 mm is the standard minimum window size.

9. Chajjas

Weather Shed is another name for Chhajjas. This is a structure built above a window that is projected outside from the window face.

Dimensional Standards for Chajja:

Chhajjas Length = Window Width + 0.15m Bearing on Both Sides 

Width of Chhajjas = 0.45 m to 0.60 m

10. Ventilators

The size of the ventilator must be at least 1000 mm x 500 mm to ensure enough ventilation for any comfortable room.

The bath and toilet should be at least 450 mm x 300 mm in size, and its depth must be more than 450 mm; you have to compromise with privacy.

11. Bathrooms And Water Closets

The height of a bathroom ceiling or water closet should be a minimum of 2.1 m (From the floor’s surface to the lowest ceiling point ). A bathroom must be at least 1.8 square meters in size and 1.2 meters wide.

The floor area of the water closet must be at least 1.1, and the width must be at least 0.9 m. The floor space must be at least 2.8 m with a minimum width of 1.2 m if a bath and a water closet are combined.

12. Staircases

The following are the minimum width, minimum tread width, and maximum riser of staircases for buildings:

  • In residential construction, the rise = 130 to 190 mm.
  • In an office building, the rise =125 and 150 mm.
  • For public buildings, the rise =275 mm to 350 mm.
  • For residential buildings, the rise =250 to 300 mm.

The thumb guidelines used to select a building’s rise and tread are as follows: 

2T X R = 550 to 650 

T x R = 39000 to 48000

The width of steps in residential structures is 900 mm, and in public buildings, it is 1000 mm.

(Total Floor Height / Riser Height) = Number of Risers

The number of treads = the number of risers -1

13. Lintel Beams

Lintels are made of reinforced concrete, and it is installed over openings in the wall such as doors and windows. The Lintel carries the load that comes through window and door openings. R.C.C. lintel beam thickness ranges from 100 to 250 mm, with 150 mm being the most common.

14. R.C.C. Roof Slab

Roofs come in various shapes, although flat and sloped roofs are the most common. Most roofs are made of R.C.C., stone, tiles, and other materials.

R.C.C. roof slabs are 100 – 150 mm thick (100 mm is most common), whereas sunshades are 25 – 50 mm thick.

15. Parapet Wall

A parapet wall is a low-rise wall that runs along the edge of a roof, terrace, walkway, balcony, or other structure.

The parapet wall height above the finished floor level should not be less than 0.60 m or more than 1.2 m.

16. Verandah

In residential buildings, the width of the verandah varies from 1.8 to 3 meters. In comparison, the width of the corridor varies from 0.8 to 1.2 meters.

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