Technical Booklet C Site Preparation and Resistance to Contaminants and Moisture·Page 22·5.5
Membrane below concrete - polyethylene sheet requirements
A membrane below the concrete must be polyethylene sheet at least 300 μm thick (1200 gauge) with sealed joints, laid on a bed of non-damaging material.
A membrane below the concrete should be formed with a sheet of polyethylene, which should be at least 300 μm thick (1200 gauge) with sealed joints and laid on a bed of material that will not damage the sheet.
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