Suspended timber ground floor construction details

A suspended timber floor next to the ground should be constructed as follows (see Diagram 5.2) – (a) ground cover – (i) unreinforced concrete at least 100 mm thick to mix ST 1 in BS 8500-1. The concrete should be laid on a hardcore bed of clean, broken brick or any other inert material free from water soluble sulfates in quantities which could damage the concrete (see Diagram 5.2a); or (ii) concrete, composed as described above, at least 50 mm thick, laid on at least 300 μm (1200 gauge) polyethylene sheet with sealed joints, and itself laid on a bed of material which will not damage the sheet (see Diagram 5.2b); (b) to prevent water collecting on the ground cover, either the top of the ground cover should be entirely above the highest level of the adjoining ground or, on sloping sites, drainage should be installed on the outside of the upslope side of the building (see Diagram 5.3).