PROVISION OF SEPARATING WALLS AND SEPARATING FLOORS
D3.1 A separating wall or separating floor must be provided between adjoining buildings or parts of a building where -
a. they are in different occupation from each other, except -
between garages in a block of garages where each garage is not more than 40m2 in area and the block is considered to be a single building for the purposes of this Part; or
b. one part of the building is in single occupation and the other is in communal occupation,except -
i. between a part in single occupation and an external access balcony or access deck;
ii. in an enclosed shopping centre, between a shop and a mall.
or:
c. they are in the same occupation but of different purpose groups,except -
where the affected parts of the building comply throughout with whatever is the most onerous of any required standard contained in this Part; or
d. each part is a unit of shared residential accommodation, as set out in D7.1.
PROVISION OF COMPARTMENT WALLS AND COMPARTMENT FLOORS
D3.2* A building, or part of a building, with a total storey area or cubic capacity which exceeds the limits given in the table to this Standard must be sub-divided into compartments which do not exceed the limits given in Table 1 to D2.1. Sub-divisions must be by compartment walls or compartment floors. In addition, but applying only to a building of purpose group 2-5,
a. a multi-storey building more than 15m high must be divided into compartments so that -i. the lowest compartment, not being a basement, is not more than 15m high;
ii. the compartment next above the lowest is not more than 9m high; and
iii. any other compartment is not more than 6m high;
b. where a building has a basement storey the floor of the ground storey must be a compartment floor, except -
where the building comprises one basement storey and not more than 2 other storeys, and no storey has a floor area more than 280m2;
c. where a building has a basement storey at a depth of more than 10m every basement storey must form a separate compartment;
d. in a building of purpose sub-group 2A every upper storey and every basement storey must form a separate compartment (see E8.19),
except -
this Standard shall not apply to -
i. a lift well, escape stair enclosure or duct enclosure, or
ii. a single storey part of a multi-storey building which complies with D3.7; or
iii. a single undivided space, including an auditorium, forming part of a building of purpose group 5.
Table to D3.2: Maximum storey area and cubic capacity of a building or compartment
|
Purpose group or sub-group |
Building form |
Maximum area of any storey within building or compartment (m2) [Note 1] |
Maximum cubic capacity of building or compartment (m3) [Note 1] |
|
1A (flats and maisonettes) |
any |
no limit |
no limit |
|
1B (houses) |
any |
no limit |
no limit |
|
1C (houses) |
any |
no limit |
no limit |
|
2A (institutional) |
any |
1500 |
8500 |
|
2B (other residential) |
any |
2000 |
14000 |
|
3 (offices) |
any |
4600 |
28000 |
|
4 (shops and commercial) [Note 2] |
any |
2800 |
7100 |
|
5A (high hazard assembly) |
any |
1900 |
no limit |
|
5B (low hazard assembly) |
any |
no limit |
21000 |
|
6A (high hazard industrial) |
single storey |
33000 |
no limit |
|
more than one storey |
2800 |
28000 |
|
|
6B (low hazard industrial) |
single storey |
93000 |
no limit |
|
more than one storey |
7500 |
no limit |
|
|
7A (high hazard storage) |
single storey |
1000 |
no limit |
|
more than one storey |
500 |
4200 |
|
|
7B (low hazard storage) |
single storey |
14000 |
no limit |
|
more than one storey |
2800 |
21000 |
|
|
7C (open-sided car parks) |
any |
no limit |
no limit |
Notes:
1. For buildings of all purpose groups except 1 and 2 these figures may be doubled if the building or compartment is provided with an appropriate automatic fire control system.
2. There is no limit to the maximum storey area or maximum cubic capacity of a building of purpose group 4 which has an appropriate fire control system and is either
i. single storey and complies with D7.2, or
ii. an enclosed shopping centre with a mall on one or two storeys which complies with D7.5.
PROTECTED ZONES
D3.3 Where any part of the enclosure to a protected zone is also a loadbearing wall or a loadbearing floor or a separating wall or a separating floor or a compartment wall or a compartment floor the most onerous period of fire resistance given by Table 2 to D2.1 for loadbearing capacity, integrity or insulation must be adopted.
PROTECTED ENCLOSURES
D3.4 A protected enclosure must be of fire resisting construction and access to or from a protected enclosure must be by way of a fire door, except -
where partitions between sanitary accommodation and adjacent rooms have at least 30 minutes fire resistance for integrity and insulation from the room side, a partition between the sanitary accommodation and the protected enclosure need not be fire resisting and any door between the sanitary accommodation and the protected enclosure need not be a fire door.
JUNCTIONS BETWEEN SEPARATING OR COMPARTMENT WALLS AND ROOFS
D3.5* Where a separating wall, compartment wall or a wall enclosing a protected zone forms a junction with a roof, no combustible material must be built into, or carried through or across the ends of, or over the top of, the wall in such a way as to impair resistance to spread of fire between the relevant parts of the building, and a suitable form of roof construction must be adopted.