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Fireproof vs Firesafe
In our search for fire resistant materials there are certain
popular misconceptions to be discarded.
First of all it is necessary to recognize that
buildings can be made only firesafe, and not fireproof.
Fireproof buildings simply do not exist.
All buildings contain enough combustible materials,
which will sustain fire in a major fire outbreak.
The heat generated in the process can cause
extensive damage to the structural elements,
which may collapse and bring about loss of life.
National Building Code of India
The Bureau of Indian Standards has brought out a
publication called “National Building Code of India”
covering the various requirements related to
construction of buildings in India.
Part IV of this publication deals with fire protection
and forms the basis for setting standards of fire
resistance for building structures.
This code has stipulated two basic requirements
related to fire resistance in building materials.
“Surface Spread of Flame” and
“Fire Resistance Ratings of Structures”. Surface spread of flame
This is a measure of flammability of the finished
surfaces of building interiors like walls,
partitions, ceilings etc. IS 1642:1960,
which is the “Indian Standard Code of Practice
for Fire Safety of Buildings (General):
Materials and Details of Construction”
has divided surfacing materials used
in building construction into four classes,
and has further given specific
recommendations for use of surfacing materials
conforming to the various classes of surface spread.
Fire resistance rating of structures
Fire Resistance of a structure such as a partition,
a wall, or a ceiling is essentially the measure of
containment of fire within a room or a building.
It indicates the protection against fire penetrating
a wall, floor, roof etc. either directly or through a
high rate of heat transfer that might cause
combustible materials to be ignited on the
side of the wall or floor away from the actual fire.
It is thus, a property of an assembly of several
materials including fastenings and of the workmanship,
and is not the property of any single material
used for construction.
I.S. code for fire resistance
IS 3809:1979 is the Indian Standard Specification
which lays down the test procedure for the
determination of fire resistance of building structures
or elements like walls, partitions etc.
A structure is rated for fire resistance in terms
of the length of time for which a test specimen
representative of that structure satisfies
certain criteria when exposed to fire,
more less simulating actual fire conditions. A brief description of the test procedure
The test for determination of fire rating is carried out,
as per the procedure laid down in IS 3809:1979, as follows: 1. A test specimen representative of the complete element
of construction, on which information is required,
is prepared in the prescribed size.
The materials used, construction and workmanship
are required to be representative of those in actual practice.
In the case of load bearing elements the
test specimen is subjected, before exposure to fire,
to a load which induces, in the critical parts of the elements,
stresses of the same magnitude as are produced
in the full size structure under normal working conditions. 2. After preparation and conditioning, the test specimen
is exposed to the prescribed fire/heating conditions
and is observed for signs of failure in any of the three
critical parameters as follows; Load Bearing Capacity
The stage at which a test specimen can no longer
support the test load is taken as the stage of failure.
The length of time for which the test specimen
has withstood the fire, supporting the test load,
is recorded. Insulation
The point of failure of an element in terms of insulation
is determined on the basis of the rise in temperature
on the unexposed face of the specimen.
The length of time taken for the temperature
on the unexposed face to rise to the
prescribed limit is recorded. Integrity
The failure of a structure in terms of integrity is
caused by the development of crack, holes or other openings,
through which flames or hot gases tend to pass.
The length of time for which the test specimen
withstands the prescribed heating conditions
without showing any sign of integrity failure is recorded. The fire rating of a structure is eventually determined
taking into account its performance in terms of some,
or all the three basic parameters; viz.
load bearing capacity, insulation and integrity,
depending on its critical functions in the building. It is thus clear that fire rating has more to do with
complete structures than with materials alone.
In the case of sheet materials used in building interiors
for partitions etc. (whether wood based or non-wood based)
a desired fire rating for any system has to be achieved by
adopting a proper design incorporating comprehensive
specifications for materials, construction and workmanship.
Thereafter a prototype of that element may be tested for
evaluation of fire rating in an institution like CBRI. Back
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