National Building Code Summary Notes

NATIONAL BUILDING CODE National Building Code: The National Building Code of India(NBC), a comprehensive building code, is a national instrument providing guidelines for regulating the building construction activities across the country. It serves as a model cede for adoption by all agencies involved in building construction works be they public works departments, other government construction departments, local bodies or private construction agencies. The code mainly contains administrative regulations, development control rules and general building requirements; fire safety requirements; stipulations regarding materials, structural design and construction (including safety); and building and plumbing services. The code was first published in 1970 at the instance of planning commission and then revised in 1 983. Thereafter three major amendments were issued, two in 1987 and the third in 1997. Considering a series of further developments in the field of building construction including the lessons learn in the aftermath of number of natural calamities like devastating earthquakes and super cyclones witnessed by the country, a project for comprehensive revision of NBC was taken up under the aegis of National Building Code Sectional Committee, CED 46 of BIS and its 1 8 expert panels; involving as many as 400 experts. As a culmination of the project, the revised NBC has now been brought out as National Building Code of India 2005 (NBC 2005). Provisions of National Building Code : ( 1) Inclusion of a complete philosophy and direction for successfully accomplishing the building projects through integrated multidisciplinary approach right through conceptual stage to planning, designing, construction, operation and maintenance stages. (2) A series of reforms in building permit process (3) Provisions to ensure and certification of safety of buildings against natural disaster by engineer and structural engineer. (4) Provisionfor two stage permit for high rise and special buildings. (5) Provision for periodic renewal certificate of occupied buildings from structural, fire and electrical safety point of view. (6) Provision for empowering engineers and architects for sanctioning plans of residential buildings up to 500 m2. (7) Inclusion of detailed town planning norms for various amenities such as educational facilities, medical facilities, distribution services, police, civil defense and home guards and fire services. (8) Revision of parking requirements for metro and mega cities. (9) Up-dation of special requirements for low income housing for urban areas. (10)Inclusion of special requirements for low income housing rural habitat planning.

(ll)Revision of the provisions for buildings and facilities for physically challenged. (12)Fire safety norms completely revamped through detailed provisions on fire prevention, life safety and fire protection. (1 3)Inclusion of new categories of starred hotels, heritage structures and archeological monuments for fire safety provisions. (14)Substitution of halon based fire/extinguishers fire fighting system. ( 15)Promotion to new/innovative building materials/technologies. (16)Inclusion of latest provisions for earthquake resistant design and construction. (17)Inclusion of details on mult-disaster prone districts. (18)Inclusion of new chapter on design and construction using bamboo. ( 1 9)Chapter on prefabricated and composite construction for speedier construction. (20)Updation of provision of safety in construction. (21 )Complete revision of provision on building and plumbing services in line with applicable international practices. (22)Provisions on rain water harvesting. (23)Inclusion of new chapter to cover landscaping needs. Building Bye-laws Building Bye-laws :Every locality has its own peculiarities in respect of weather conditions, availability of materials and labour and thus adopts its own methods of construction. Every locality prepares certain rules and regulations which help in controlling the development of the locality. The rules and regulations covering there requirements of buildings, ensuring safety of the public through open spaces, minimum size of rooms, and height and area limitation, are known as building byelaws. Objective of Bye-laws: The building bye-laws are necessary to achieve the following objectives : (i) It prevents construction of buildings in a haphazard manner. (it) It lays down guidelines tc be followed by architect/engineer in involving the building layout and plans to ensure planned development of the area as a whole. (iii) The building which are planned based on bye-laws are comfortable to live in, have proper light and ventilation and are safe.

(iv) Bye-laws serve as a standard document for the local bodies to lawfully enforce the prescribed norms in the planning of buildings by the architect.

Importance of Building Bye-laws. Every locality has its own pecularities in respect of weather conditions, availability of materials and labour and thus adopts its own methods of construction. Every locality prepares certain rules and regulations which help in controlling the development of the locality. The rules and regulations covering the requirements of buildings, ensuring safety of the public through open spaces, minimum size of rooms, and height and area limitation, are known as building bye-laws. The building bye-laws are necessary to achieve the following objects. (i) Building bye-laws give guidelines to the architects or Engineer and thus help in pre-planning the building activities. (ii) Building bye-laws allow orderly growth and prevent haphazard development. (iii) Provisions of bye-laws usually afford safety against fire,, noise, health hazard, and structural failure. In the absence of suitable building bye-laws, the people will construct residences lacking in amenities and health conditions, with profit: as the only motive. Hence only framing of building byelaws is not sufficient. If desired results are to be achieved there should be proper authorilty who could enforce the building bye-laws. While framing building bye-laws assistance of experts on various subjects such as town planning, law, health, civil engineering, traffic, general administration etc. should be sought and their views given due weightage. Now the importance of building bye-laws is being increasingly realised. Indian Standard Institution, an organization of Government of India has published I.S. 1256 "code of building laws" covering all the salient aspects of building activities. Having realised the importance of building bye-laws and also to smoothen the work of local enforcing authorities Government of India has published National Building Code (NBC). This publication covers all the aspects of building activities and embodies all the relevent Indian Standards and thus has been taken as an advisory document by all the local authorities, government and semi- government departments and other construction agencies. The; document has been drafted with performance orientation and gives better freedom to architects and engineers. In case of any difficulty or dispute the provisions of N.B.C. form the basis of deciding the things BUILDING LINES Building Lines :Building line refers to the line of building frontage. It is a line up to which the plinth of a building adjoining a street or an extension of street or on a future street may lawfully extend. This line is also known as front building line or set back line. This line is laid parallel to the plot boundary

by the authorities. Beyond this line nothing can be constructed towards the plot boundary. The building such as cinemas, business centers, factories etc. which attract large number of vehicles, should be further set back from the building line. The line which accounts for this extra margin is known as control line. Sometimes, a line is fixed and no building or its portion should be projected beyond this line. This line is drawn at the front of the building and is known as general building line. The position of building line depends upon the site of the proposed building, keeping in view the present width and future winding requirements .A minimum distance either from boundary of the road or center line, is prescribed for the line of building frontage. The table 2.2 gives some idea of such distances from building and control lines specified for different types of areas

In urban areas distance of control line is taken as 1.5 times that of building line. These distance are measure from the centre of the roadway. National building code specifies a minimum frontage of 6m on any street. Following are the advantages of fixing building lines: (i) Future widening of street is possible. (ii) Noise and dust of street is kept away. (iii)

Formation of blind corners at the intersection of streets is prevented.

PLINTH AREA, FLOOR AREA AND CARPET AREA. PLINTH AREA : This is built-up covered area measured at the floor level of the basement of any storey. The following shall be included in the plinth area: (i) Area of the walls at the floor level excluding plinth offsets, if any, when the building consists of columns projections beyond cladding. (ii) Internal shafts of sanitary installations, provided there do not exceed 2m2 in area, air-conditioning ducts; lifts etc. (iii) Porches and other cantilevers provided. (iv)The area of barsati and the mumty at terrace level. The following shall not be included in the plinth area : (i) Area of lofts. (ii) Internal sanitary shafts provided there are move than 2m2 in area. (iii) Unclosed balconies. (iv)Unless they form a storey at the level, towers, times, domes projecting above the terrace level at terrace. (v) Architectural bands, cornices etc. (vi) Vertical sun breakers or box louvers projecting out. FLOOR AREA : This is the usable covered area of building at any floor level. To get floor area, the area of walls shall be deducted from the plinth area to arrive at the floor area. The following shall be included in the wall area: (i) Door and other opening in the wall. (ii) Internal pillars and supports. (iii)Plaster along walls exceeding 300cm2 in area. (iv)Flues which are within the walls. The following shall be excluded from the wall area :

(i) Plaster along wall each not exceeding 300 cm2 in area. (ii) Fire place projecting beyond theface of the wall in living or bedrooms. (iii)Chullah platforms projecting beyondthe wall of kitchen. CARPET AREA : This is the floor area of the usable rooms at any floor level. The carpet area of any shall be the floor area worked as per floor area and exclude the following portions of the building: (i)

Sanitarv accommodations

(ii)

Verandahs

(iii)

Corridors and passages

(iv)

Kitchen and pantries

(iv)

Stores in domestic buildings

(v)

Entrance hall and porches

(vi)

Staircases

(vii)

Shafts for lift

(xi)

Barsaties

(x)

Garges

(xi)

Canteens

(xii) Air-conditioning ducts and air-conditioning plant rooms.

FLOOR AREA RATIO FloorArea Ratio (FAR): It is the quotient obtained by dividing the total covered area (Plinth area) on all the floors multiplied by 100, by the area of the plot.

The limitation of area and height of buildings of different types of construction and occupancy class is achieved by specifying it in terms of FAR.

The floor area ratio is also termed as floor space index or F.S.I. The maximum area which can be allowed to be built on a plot of land and the maximum height upto which construction can be carried out on a plot is governed by the F.A.R. prescribed for the site by the local authority. The various aspects that are considered in specifying the value of F.A.R. for a site are given below. (i) Type of occupancy i.e. residential or non-residential (ii) Type of construction (iii) Width of street fronting the proposed building and the traffic load. (iv)Locality where the building is proposed and the density of that area. (v) Parking facilities (vi) Water supply, drainage and fire fighting facilities National Building Code (N.B.C.) has laid down certain value of F.A.R. for different occupancies and type of construction. The local authority arrives at the values of F.A.R. for the area under its juridistion by adopting the basic F.A.R. value as give in N.B.C. and modifying the same based on local factor or consideration. Hence if the area of a given plot is 400 sq.m and if the F.A.R. prescribed by the local authority for the site is 1 .5 than the maximum total area of building that can be constructed on such a plot would be = 1.5 x 400 = 600 sq.m. Depending upon the width of the road fronting the plot one can have a 4 storeyed building each floor having an area of 150 sq.m. or 3 storeyed building each floor having an area of 200 sq.m. Plot Coverage :Besides F.A.R., the local authority also specify the maximum permissible ground coverage (covered area of the building on ground) for different type of occupancies (residential or non-residential) which are required to be respected by the architect in evolving, the design of the building and deciding upon the number of stories/height of the building. List out the various aspects of building activities covered by the bye-laws The various aspect of building activities covered by the byelaws is summarised as under : (i) Distance from electric lines (ii) Lines of building frontages (iii) Open space within a plot. (iv) Built up area limitations . (v) Norms relating to size and height of rooms and other requirements of part of buildings (vi) Lighting and ventilation of rooms (vii) Parking spaces

(viii) Exit requirements (ix) Fire protection requirements (x) Structural safety requirements _ (xi) Buildingservices OPEN SPACES. Every building should have provision of open spaces, inside and around the building to cater to the requirement of natural light and ventilation of the room abutting such open spaces. In case of building abutting on streets in the front, rear or sides, the extent of open spaces provided should be sufficient to permit future widening of such streets. (i) Front Open Space :The width of the open space which is required to be provided for a buildingdepends upto the width of the street fronting the plot.As per National BuildingCode, every buildingfronting a street should have a front space forming on integral part of site as below :

For streets less than 7.5 m in width the distance of building shall be at least 5m from the centre line of the street. (ii) Rear Open Space :Every residential building should have a rear open space forming an integral part of site of an average width of 3m. For plots of depth less than 9m, for building upto 7m in height, the rear open space may be reduced to 1 ,5m. (iii) Side Open Space : Every semi-detached and detached building should have open air space as under: (a) For detached building ....3 m (minimum) on both sides. (b) For semi-detached buildings ...3 m (minimum) on one side. For building of a height above 10m: The open space (side and rear) shall be as given in table 2.3.

For buildings above 24 m in height there should be a minimum front open space of 6m. HEIGHT OF BUILDING : The height of the building is decided by two factors. (i) By the width of the street on which it fronts. (ii) The minimum width of rear open space. InNational BuildingCode the height and number of storey are related to FAR and provisions of open spaces. The maximum height generally limited on the basis of the width of street is given as follows : a) The maximum height of building shall not exceed 1.5 times the width of road abutting plus the front open spaces. b) If a building abuts on two or more streets of different width, the building shall be deemed to face upon the street that has the greater width and the height of the building shall be regulated by the width of that street. Height shall however, not exceed the maximum height as provided in the Master Plan. c) For buildings in the vicinity of the aerodromes the maximum height of such buildings shall be subject to clearance from the Civil Aviation Authorities from time to time and to this effect a no objection certificate issued by that Authority shall be submitted by the applicant along with plans to the sanctioning Authority.