BS EN 492:2012 pdf download – Fibre-cement slates and fittings — Product specification and test methods
5.1.2 Appearance and finish
The exposed face of the fibre-cement slates may be with or without texture. The fibre-cement slates may be coloured or left in their natural colour.
The fibre-cement slates may also receive adherent coloured or uncoloured coatings on their surface. The fibre-cement slates may be supplied with holes for fixing. On exposure, the surface and/or its coating will be affected by weathering which may vary with site location, aspect, pitch of roof and duration of exposure. Any deterioration in this respect shall not detract from the minimum mechanical and physical characteristics as specified in this document or from the function of the fibre-cement slate as a durable element. The fittings shall have a general appearance and finish compatible with the fibre-cement slates with which they are to be used. They may be supplied with holes for fixing.
5.2 Dimensions and tolerance
5.2.1 General The manufacturer shall specify the shapes, sizes and configuration of edges. NOTE See 5.6 for designation and information. Fittings shall have nominal dimensions and shapes determined by the manufacturer and appropriate to the corresponding fibre-cement slates.
5.2.2 Thicknesses The actual fibre-cement slate thickness determined in accordance with 7.2 shall be not less than that shown in Table 1. The nominal thickness shall be specified by the manufacturer. The nominal thickness of the fittings shall be not less than the corresponding nominal thickness of the fibrecement slates with which the fittings are to be used.
5.2.3 Tolerances on nominal dimensions
The maximum dimensional variation when measured as specified in 7.2 shall be as follows: Length and width: ± 3 mm;
Thickness: 25 10 + − % of the nominal value.
For fittings that replace fibre-cement slates (e.g. ventilation fibre-cement slates) the tolerances shall be the
same as those on the fibre-cement slates.
For other fittings (e.g. ridges) the tolerances shall be specified by the manufacturer.
5.3 Physical requirements and characteristics for fibre-cement slates
Mechanical and material properties are determined on products as delivered, wherever practicable. The results shall be identified as applying to coated or uncoated material.
NOTE See 6.3 for statistical interpretation.
5.3.2 Apparent density
The manufacturer’s literature shall specify the minimum apparent density of the fibre-cement slates. The fibrecement slates shall have an apparent density equal to or greater than that specified by the manufacturer when tested in accordance with 7.3.1.
5.3.3 Mechanical characteristics
When tested in accordance with 7.3.2, the fibre-cement slates shall have a minimum average bending moment per metre width in newton metres per metre as specified in Table 1.
The minimum bending moment at rupture in the weaker direction shall be not less than 60 % of the values specified in Table 1 for the average in both directions.
5.3.4 Water impermeability
When tested in accordance with 7.3.3, traces of moisture may appear on the under face of the fibre-cement slate, but in no instance shall there be any formation of drops of water.
Mechanical and material properties are normally determined for as delivered products. The results shall beidentified as applying to coated or uncoated material. Performance of the coating in the tests specified in 5.4.2and 5.4.3 shall not be considered in the assessment of the product.
When tested in accordance with 7.4.1 after 100 freeze-thaw cycles, the ratio R[ as defined in 22.214.171.124 shall benot less than 0,75.
When tested in accordance with 7.4.2 after 50 heat-rain cycles, any visible cracks,delamination or otherdefects in the fibre-cement slates shall not be of such degree as to affect their performance in use.
Water tightness is assessed according to 5.3.4.
Warping and bowing are visually assessed.
When tested in accordance with 7.3.4, after 56 days at 60 C, the ratio R_as defined in 126.96.36.199 shall be notless than 0,75.
When tested in accordance with 7.3.5, after 50 soak-dry cycles, the ratio R_as defined in 188.8.131.52 shall be notless than 0,75.