Permissible height of buildings - a comparison of three cities
Though the definition of high-rise buildings and the rules vary from city to city, the guiding principle is the same, writes Suresh Kuppuswamy
— Photo: K.V. Srinivasan
Important parameter: The height of a building dictates the number of floors buildable and thereby establishes the maximum buildability in a plot.
Height of a building means the vertical distance measured from the ground level. The height of parapet walls, staircase head rooms, lift machine room and architectural features is normally excluded in computing the height. It is an important planning parameter as it dictates the number of floors buildable and thereby establishes the maximum buildability in a plot. As the buildings become taller they attract the provisions of the National Building Code with regard to fire s
afety and stability factors. The definition of high-rise buildings and the rules pertaining to them vary from city to city.
Buildings in the Chennai Metropolitan Area are broadly classified as ordinary buildings, special buildings and multi- storeyed buildings based on the height by the CMDA. Any building that exceeds 15.25M is termed as a Multi-storeyed Building (MSB). In order to encourage amalgamation of smaller plots into large plots and provide large open space, a higher FSI of up to 2.75 is permissible in MSBs. They are permitted anywhere within the city limit except in a few restricted locations.
For a plot to qualify for an MSB, it should have a minimum extent of 1500 M2 and it should gain access from a road of width 18M. The maximum permissible height for an MSB is 60M or one and half times the width of the road which ever is higher. In the case of IT buildings it is 60M or twice the width of the road whichever is higher. There are no stipulations with regard to the number of floors that can be constructed. Since FSI is the limiting factor, a designer can explore many options before deciding on the height of the building. Other factors such as plot coverage and set backs are also to be considered.
For special buildings, the maximum permissible height is 15.25M and within this height a ground + 3 floor building or a building with stilt + 4 floors are permissible provided the portion of the building on the stilt is used only for parking of vehicles. Special buildings are permitted only on roads having a width of 10M. In the case of ordinary buildings only two floors are permitted irrespective of the width of the road.
The provisions mentioned above are retained in the draft Master Plan II. The only relaxation being that the MSBs are proposed to be permitted in the entire Chennai Metropolitan Area. At present, this provision is applicable only for IT buildings.
In the Bangalore Metropolitan Area, buildings exceeding 24M in height are termed as high rise buildings (an alternative term for MSB). Unlike Chennai and Hyderabad, there is no direct relation between the permissibility of a high rise building and the width of the road. Road width factor is important for the FAR (Floor Area Ratio -synonymous with FSI) directly in addition to the other parameters such as plot size and ground coverage (plot coverage). The general rule is that the bigger the plot and the wider the road the more is the buildability. For plots having an extent of 1000 to 2000 M2, which is more or less comparable to Chennai, on roads having width from 18 to 24M, an FAR of 2.5 is allowed for residential developments. Since the FAR is the limiting factor, a designer has the freedom of determining the height of the building based on plot coverage and set back requirements.
Even though there is no specific requirement of road width for taller buildings, on roads having width up to 9M, the height of the building is restricted to 11.5M irrespective of the FAR permissible. In such buildings stilt + 3 floors are permissible. The set back requirements depend on the width and depth of the plot. The setback requirements for buildings exceeding 11.5 M are more stringent.
Since the FAR and plot coverage factors have been dispensed with in the Hyderabad Metropolitan Area, the height of the building becomes a sole governing factor in deciding the maximum buildability. Buildings are broadly classified as high-rise buildings and non-high rise buildings based on height. Buildings exceeding 18M are termed as high rise buildings and buildings below 18M are termed as non-high rise buildings.
High-rise buildings are permissible only in plots having an extent of 2,000 M2 and above. The height of the building is governed by the width of the road. The set back requirements are directly based on the height of the building proposed.
High-rise buildings are not permitted in congested areas /old settlement areas, certain notified areas within the Municipal Corporation of Hyderabad and on roads having width less than 30M in the MCH. In new areas and approved layout areas high-rise buildings intended for residential and institutional uses are permitted on roads having 12.2M width. There is no upper limit specified for high rise buildings and a notable feature is that in areas designated, as sky scraper zone, the minimum height of high-rise buildings permitted is 36M and above. In such zones, the minimum plot size should be 4000 M2 and the road width not be less than 24M.
In the case of non-high rise buildings, those up to a height of 18M are permitted in the existing built-up areas/congested areas even on roads having a width of 9M.
In new areas and approved layout areas, residential buildings up to 15M height are permitted on roads having 9M width. For non-residential buildings having a height of up to 18M are permitted only if the site abuts a road having 12.2M width and the height permitted is directly proportional to the size of the plot. Even though the models adopted in the three cities vary from one other, the guiding principle is more or less the same. The width of the road is an important factor in determining the carrying capacity. It governs the height of the buildings.
The author is Professor, School of Architecture and Planning, Anna University, Chennai.
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