BS 493:1995+A1:2010

This British Standard specifies requirements for two classes of wall ventilating units as follows: class 1:airbricks for useinexternal walls; class 2: wall ventilators or gratings for internal use. Some typicalexamples of designs are shown in Figure 1, Figure 2 and Figure 3. Other patterns may however be supplied, provided they conform to the requirements of this standard. Guidanceon the information to be supplied by the purchaser when ordering is given in Annex A. Thisstandard contains no requirements for the following properties. Durability (other than resistance to colour change of thermoplastics materials). It is recommended that where there is uncertainty about durability then expert advice should be sought. Fire properties of thermoplastics materials. The general useof thermoplastics airbricks, wall ventilators and gratings in isolation in masonry is considered to have aninsignificant effect on the spreadoffire.However, special consideration should begiven to the use of thermoplastics air bricks where it is intended to group a number of them together, e.g. for boiler house ventilation. Compressive strength of thermoplastics air bricks. The general use of these in isolation is considered to have to have an insignificant effect on masonry strength. However, special consideration should be given to their use where it is intended to group a number of them together, e.g. for boiler house ventilation.