The word ‘waterproof’ is an absolute term. It means ‘impervious to water’. Stating that a building is almost waterproof does not make sense.

The term cold roof can be a little misleading. We call them ‘cold’ due only to placement of the insulation being separated from the membrane substate, or more technically; the internal air can circulate underneath the roof.

A tanking membrane is designed to be a continuous protection against hydrostatic pressure at all times i.e. to be waterproof.

One critical area of waterproofing is to ensure the detail you use to seal the penetrations for the shower mixers/taps and their associated outlets not only completely seals the penetrations from water ingress from the outside, but will also provide protection to the wall cavity.

Where a BGT system connects with a Damp Proof Membrane (DPM) is a detail that many designers have drawn without fully understanding how these dissimilar membranes are connected.

The Waterproofing Membrane Association Inc. (WMAI) develop a range of Codes of Practice (COP) for Water Proofing Membrane(s) (WPM) for all situations.