(1)
Where dampproofing is installed below the floor, it shall consist of
(a)
polyethylene not less than 0.15 mm thick with joints lapped not less than 100 mm,
(b)
Type S roll roofing with joints lapped not less than 100 mm, or
(c)
rigid extruded/expanded polystyrene with sealed or shiplapped joints that has
(i)
sufficient compressive strength to support the floor assembly, and
(ii)
a water vapour permeance complying with Clause 9.13.2.2.(2)(a). (See Note A-9.13.2.6.(1))
(2)
Where dampproofing is installed between a floor-on-ground and a finished floor, it shall consist of
(a)
rigid extruded/expanded polystyrene with sealed or shiplapped joints that has
(i)
sufficient compressive strength to support the floor assembly, and
(ii)
a water vapour permeance complying with Clause 9.13.2.2.(2)(b), or
(b)
polyethylene not less than 0.05 mm thick with joints lapped not less than 100 mm.