For fire protection, floors are categorised depending on their
height relative to adjacent ground ~
Tests for fire resistance relate to load bearing capacity, integrity
and insulation as determined by BS 476 † 21: Fire tests on building
materials and structures. Methods for determination of the fire
resistence of loadbearing elements of construction.
Integrity ~ the ability of an element to resist fire penetration and
capacity to bear load in a fire.
Insulation ~ ability to resist heat penetration so that fire is not
spread by radiation and conduction.
Typical applications ~
38 mm timber joists with
noggins or struts to
support board edges
12.5 mm plasterboard,
joints taped and filled
50 mm timber joists with
noggins or struts to
support board edges
two layers of 15 mm
plasterboard
independently
nailed with joints
taped and filled
600 mm max. spacing
600 mm max. spacing
40 mm galv. steel clout
nails at 150 mm spacing
60 mm galv. steel clout
nails at 150 mm spacing
21 mm t & g wood
board flooring
21 mm t & g wood
board flooring
30 MINUTE FIRE RESISTANCE
60 MINUTE FIRE RESISTANCE
Ref. Building Regulations, AD B Fire safety, Volume 1 † Dwellinghouses.
Height of top floor above ground Fire resistance
(load bearing)
Less than 5 m 30 minutes (60 min.
for compartment floors)
More than 5 m 60 minutes (30 min. for
a three storey dwelling)
Timber Upper Floors---Fire Protection