1985 Ed.]
Building (Construction) Regulations
[CAP. 123
B 93
(5) Subject to the provisions of Part XVI (Fire Resisting Construction), the thickness of topping, after allowance has been made for the effect of wear if necessary, shall be not less than 50 mm or the clear distance between the ribs, whichever is the greater.
(6) (a) The width of the rib shall be not less than 75 mm.
(b) The depth, excluding any topping, shall be not more than 3 times the width.
(c) The spacing shall be not more than 750 mm measured from centre to centre.
(7) At least 50 per cent of the total positive reinforcement in ribs shall be carried through at the bottom on to the bearing and effectively anchored.
(8) For the purpose of determining the positive reinforcement in the span, floors continuous over supports may be treated as simply supported, in which case, negative reinforcement shall-
(a) be provided over the support to prevent cracking:
(b) have a cross-sectional area of not less than ¼ of the positive reinforcement in the middle of the adjoining bays; and
(c) extend at least ¼ of the clear spans into the adjoining bays.
(9) Notwithstanding regulation 115 (minimum cover to reinforcement) and subject to the provisions of Part XVII (Fire Resisting Construction), cover to reinforcement shall be not less than 20 mm or the diameter of the bar, whichever is the greater, exclusive of any finishing materials.
(10) Notwithstanding regulations 123, 124 and 125, the topping slab shall be reinforced with-
(a) main reinforcement at right angles to the ribs, required for flexure, but not less than 0.3 per cent of the gross cross-sectional area of the concrete and spaced at a distance not more than 4 times the total thickness of the topping; and
(b) distribution reinforcement at right angles to the main reinforcement of an amount not less than 0.15 per cent of the gross cross-sectional area of the concrete and spaced at a distance not more than 5 times the total thickness of the topping:
Provided that the diameter of the main reinforcement shall be not less than 6 mm where bars are used or 5 mm where fabric is used.
(11) Where blocks are used in between cast-in-situ ribs as part of the completed floor or roof, they shall not be placed within 75 mm from the walls or beams at right angles or parallel to the ribs.
[Subsidiary]
L.N. 294/76.
1985 Ed.]
Building (Construction) Regulations
[CAP. 123
B 93
(5) Subject to the provisions of Part XVI (Fire Resisting Construction), the thickness of topping, after allowance has been made for the effect of wear if necessary, shall be not less than 50 mm or the clear distance between the ribs, whichever is the greater.
(6) (a) The width of the rib shall be not less than 75 mm.
(b) The depth, excluding any topping, shall be not more than 3
times the width.
(c) The spacing shall be not more than 750 mm measured from
centre to centre.
(7) At least 50 per cent of the total positive reinforcement in ribs shall be carried through at the bottom on to the bearing and effectively anchored.
(8) For the purpose of determining the positive reinforcement in the span, floors continuous over supports may be treated as simply supported, in which case, negative reinforcement shall-
(a) be provided over the support to prevent cracking:
(b) have a cross-sectional area of not less than } of the positive reinforcement in the middle of the adjoining bays; and
(c) extend at least of the clear spans into the adjoining bays.
(9) Notwithstanding regulation 115 (minimum cover to rein- forcement) and subject to the provisions of Part XVII (Fire Resisting Construction), cover to reinforcement shall be not less than 20 mm or the diameter of the bar. whichever is the greater, exclusive of any finishing materials.
(10) Notwithstanding regulations 123, 124 and 125, the topping slab shall be reinforced with-
(a) main reinforcement at right angles to the ribs, required for flexure, but not less than 0.3 per cent of the gross cross- sectional area of the concrete and spaced at a distance not more than 4 times the total thickness of the topping; and
(b) distribution reinforcement at right angles to the main
reinforcement of an amount not less than 0.15 per cent of the gross cross-sectional area of the concrete and spaced at a distance not more than 5 times the total thickness of the topping:
Provided that the diameter of the main reinforcement shall be not less than 6 mm where bars are used or 5 mm where fabric is used.
(11) Where blocks are used in between cast-in-situ ribs as part of the completed floor or roof, they shall not be placed within 75 mm from the walls or beams at right angles or parallel to the ribs.
[Subsidiary]
L.N. 294/76.
i
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