Fire resistance

Minimum periods for elements of structure
(minutes)

Building type Basement storey Ground and upper storeys
more than less than less than less than less than more than
10 m deep 10 m deep 5 m high 20 m high 30 m high 30 m high
Flats and maisonettes 90 60 30a 60c 90b 120b
Houses n/a 30a 30a 60 n/a n/a
Institutionald
, residential 90 60 30a 60 90 120e
Offices without sprinklers 90 60 30a 60 90 X
with sprinklers 60 60 30a 30a 60 120e
Shops & without sprinklers 90 60 60 60 90 X
Commercial with sprinklers 60 60 30a 60 60 120e
Assembly & without sprinklers 90 60 60 60 90 X
Recreational with sprinklers 60 60 30a 60 60 120e
Industrial without sprinklers 120 90 60 90 120 X
with sprinklers 90 60 30a 60 60 120e
Storage & otherwithout sprinklers 120 90 60 90 120 X
non-residential with sprinklerss 90 60 30a 60 90 120e
Car parks for open sided park n/a n/a 15f 15f 15f 60
light vehicles any other park 90 60 30a 60 90 120e
X = not permitted
a Increased to 60 minutes for compartment walls separating buildings.
b Reduced to 30 minutes for any floor within a maisonette, but not if that
floor contributes to the support of the building.
c As b above and, in the case of existing houses, of no more than three
storeys being converted into flats. This may be reduced to 30 minutes
providing the means of escape conform to section 2 of requirement B1.
d Multi-storey hospitals should have a minimum 60 minutes standard.
e Reduced to 90 minutes for elements not forming part of the structural
frame.
f As a above and increased to 30 minutes for elements protecting the
means of escape.