1964_BUILDING_(CONSTRUCTION)_REGULATIONS

1985 Ed.]

Building (Construction) Regulations

[CAP. 123

B 53

[Subsidiary]

PART X

STRUCTURAL USE OF TIMBER

86. (1) Every joist, binder, rafter and purlin shall have a finished breadth of not less than 35 mm.

(2) Floor boards and boarding to flat roofs shall have a finished thickness of not less than 16 mm.

87. (1) For the purpose of determining the sizes of ceiling joists, a total load shall be taken of not less than 1 kPa, but for the purpose of designing the construction supporting those joists, the total load may be taken as 0.5 kPa.

(2) For the purpose of determining the required thickness of tongued and grooved floor-boards, an imposed load shall be taken per meter width of the boarding of not less than the load for slabs specified in column 4 of Table VII for the type of floor specified in that Table.

(3) Where plain-edged floorboards are used, each floorboard shall be capable of resisting, without exceeding the maximum permissible stress specified in Table XVII, the load for slabs specified in column 4 of Table VII for the type of floor specified in Table VII, irrespective of the width of the floorboards.

(4) Subject to the provisions of regulation 86(2), the required thickness of floorboards shall be not less than the thickness determined by calculation plus 2 mm for wear.

88. (1) Subject to the provisions of regulation 92, the stresses in structural timber, other than posts and struts, shall not exceed the maximum permissible stresses specified in Table XVII.

TABLE XVII

Maximum permissible stresses in structural timber other than posts and struts; in MPa

Kind of stresses Class of timber A B Flexural stress in extreme fibres (other than floorboards) with adequate lateral restraint against winding or buckling 7.0 5.5 Flexural stress in extreme fibres of floorboards 3.5 Shear stress in direction of grain 0.7 0.7 Compressive stress perpendicular to grain 3.4 Tension in direction of grain 10.3 8.3 Modulus of elasticity (mean) 11,000 7,000 Modulus of elasticity (minimum) 8,300 5,200

Finished sizes of structural timber. L.N. 294/76.

Minimum load on ceiling joists and floor boards.

L.N. 294/76

Maximum permissible stresses in structural timber.

L.N. 294/76