The maximum height of a building is limited according to the width of the road and generally it shall not exceed 1.5 times the width of the road abutting plus the front open space. The limitation of area and height of buildings of different occupancy classes and types of construction shall be achieved by specifying it in terms of FAR (Floor Area Ratio). The FAR will vary depending on the location of the building and the prevailing building by-laws. Based on the allowable FAR and road width, the architects/builders decide the ceiling heights in consultation with the occupants.
As per the National Building Code of India 2005, the height of all rooms for human habitation shall not be less than 2.75 m measured from the surface of the floor to the lowest point of the ceiling (bottom of the slab). In the case of pitched roof, the average height of rooms shall not be less than 2.75 m. The minimum clear head room under a beam, folded plates or eves shall be 2.4 m. In the case of airconditioned rooms, a height of not less than 2.4 m measured from the surface of the floor to the lowest point of air-conditioning duct or the false ceiling shall be provided. For kitchens it is 2.75m, bathrooms 2.1m, lofts 2.2m, mezzanine floors 2.2m, store rooms 2.2m, and basements 2.4 m.
The ceiling heights for educational buildings is 3.6 m (cold regions 3m) and for industrial buildings it is 3.6 m (when airconditioned, 3.0m).
Architects design rooms, halls etc keeping in mind the volume of the space, ventilation and natural lighting requirements and not just the plan sizes. One has to visualise it in three dimensions before finalising the heights. A building can have same ceiling height throughout or it can have higher heights for living areas by providing split levels and double heights.
A lot of research and survey has been conducted world over to decide on the ceiling of ceiling heights! It all finally depends on the comfort of the user. The ceiling heights depend on many factors.
Clearance: Should be comfortable for the tallest individual, depends on the type of ceiling fixtures like lights, fans, ornamental hangings etc. Clear and safe head room below these fixtures is very important.
Temperature: Thermal comfort and radiation from the ceilings are important points. If there is a mechanism to control the radiation, it is better to have higher ceiling height
Ventilation: Higher ceiling heights will have better air circulation but it can also be achieved by proper design and placement of windows and ventilators.
Light and sound: Lower ceilings will necessitate more windows and ventilators for better light and sound effects.
Economics: Lower ceilings will be cost effective as there is savings in the construction materials and it is possible to build more storeys.
University of Minnesota researchers find that ceiling height can affect how a person thinks, feels, and acts.
“When a person is in a space with a 10-ft. ceiling, he/she will tend to think more freely, more abstractly,” said Meyers-Levy. “He/she might process more abstract connections between objects in a room, whereas a person in a room with an 8-ft. ceiling will be more likely to focus on specifics”.
(The author is a Professor at BIT and Secretary General, ACCE-I)