B 126
CAP. 123]
Building (Construction) Regulations
[1985 Ed.
[Subsidiary]
TABLE B
FLOORS AND LANDINGS
Minimum thickness in mm for period of
2
3
Construction and Materials
4
2 hours hours hour hour
+
Filler Joist Construction
Thickness of concrete
Concrete cover on bottom of joist
25 25
22
150 125 100 90
=
15
15
SOLID REINFORCED CONCRETE CONSTRUCTION
(including flat slab construction and floors constructed of precast inverted “U”, channel or T-sections, without a ceiling or soffit).
Thickness of concrete
150
125 100 90
Concrete cover to reinforcement
25
15 15
15
HOLLOW BLOCK FLOOR CONSTRUCTION
(including floors constructed of precast concrete units of box-section or I-section).
Aggregate thickness of incombustible material
(excluding ceiling finishes (if any))
125
90 75
65
Concrete cover to reinforcement
25
15
15
15
STRUCTURAL TIMBER CONSTRUCTION
Boards 22 mm thick on timber joists not less than
175 mm deep by 50 mm wide.
(a) Tongued and grooved boards with ceiling
of:-
(i) timber lath and plaster
Thickness of plaster
(ii) metal lath and plaster
Thickness of plaster
(iii) 2 layers of plaster-board, each
minimum thickness
(iv) 1 layer of plaster-board of minimum
thickness
(v) 1 layer of plaster-board of minimum thickness of 9.5 mm covered with gypsum plaster of minimum thickness
16
16
9.5
19
16
(b) Plain edge boarding with ceiling of:-
(i) metal lath and plaster
Thickness of plaster
16
(ii) timber lath and plaster with plaster of
minimum thickness of 16 mm. covered with sheets of plaster-board of minimum thickness
9.5