BS 747:1994 pdf download.Roofing felts.
1 Scope This British Standard specifies requirements for roofing felts intended for use in the British Isles and countries with similar climate.
2 References This British Standard incorporates, by dated or undated reference, provisions from other publications. These references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cited applies; any subsequent amendments to or revisions of the cited publication apply to this British Standard only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments.
3 Class 1. Bitumen felts (fibre base)
3.1 Introduction The felts in this class are: 1F reinforced bitumen felt 1F reinforced bitumen felt, aluminium faced. They are made from a continuous roll of unproofed, absorbent fibre. Minimum masses for the base and bitumen components are given in Table 1.
3.2 Requirements for constituent materials
3.2.1 Base The base shall consist of animal or vegetable fibres made into a close-textured absorbent sheet of fibre felt.
3.2.2 Saturating material The saturating material shall consist of bitumen conforming to BS 3690-2 having a penetration within the range 60 to 230 at 25 °C when tested in accordance with BS 2000-49.
3.2.3 Coating material The coating material shall have a softening point (ring and ball test) within the range 80 °C to 120 °C when tested in accordance with BS 2000-58 and shall consist of oxidized bitumen conforming to BS 3690-2 which may be stabilized with finely divided mineral filler. The proportion of stabilizing mineral filler shall not exceed 40 % by mass of the coating material.
3.2.4 Mineral filler The mineral filler shall consist of finely divided mineral matter of which not less than 99 % by mass passes a 212 µm mesh BS sieve conforming to BS 410.
3.2.5 Surfacing material The surfacing material shall consist of a suitable quality of natural sand, mineral granules or other suitable material according to the type of felt.
3.3 Type 1F reinforced bitumen felts 3.3.1 Description 1F felt is a bitumen saturated and coated fibre base felt combined with a layer of jute hessian embedded in the coating on one side of the felt so as to reinforce and strengthen the sheet. The sheet is surfaced with a surfacing material to prevent the felt sticking in the roll. The presence of the hessian is obvious on inspection.BS 747 pdf download.