Under floor membranes

Polyolefin membranes should be placed beneath all slab-on-the-ground foundations, irrespective of site and ground conditions.

The membranes should have a thickness of not less than 0.25mm and should be placed beneath the slab and beam thickenings so that the bottom surface in entirely laid.

Where justified by appropriate geotechnical conditions, the membrane as in the case of slab-on-the-ground features, may be terminated at the face or edge of the internal beam.

Lapping of membranes at joints should not be less than 200mm.

Penetrations by pipes, plumbing fittings or punctures should be taped with a pressure sensitive adhesive tape.

In the case of floor tabs, the membranes should be turned up around the perimeter of the floor slab by at least the thickness of the slab.