Use waterproofing where it matches the actual water-entry problem.
Waterproofing should not be treated as a general coating for every leaking roof. The affected area, substrate and likely water path need to be understood first so the work addresses the cause rather than only covering the visible symptom.
Assess, prepare and waterproof the right areas.
Assess
Review the affected roof area, water-entry symptoms, substrate and surrounding details to understand the problem.
Prepare
Define the required repairs and surface preparation before the waterproofing work is carried out.
Waterproof
Apply the agreed waterproofing or remediation scope to the prepared areas and details.
Preparation is part of the waterproofing work.
The condition of the surface and surrounding roof details affects the repair. Damaged areas may need to be repaired, cleaned or otherwise prepared before the waterproofing system is applied. The required preparation depends on the existing condition and selected scope.
Find the likely source before choosing the repair method.
If the water-entry source is unclear, the roof should be assessed before waterproofing is specified. The right solution may involve waterproofing, a roofing repair or work to flashings, penetrations, drainage or another related detail.
Roof leak detectionRoof waterproofing — common questions
Which roofs use membranes rather than sheets or tiles?+
Flat and very low-pitch roofs, roof decks, balconies and planter boxes, where water cannot shed fast enough for sheet or tile roofing. Membranes for roofs, decks and balconies are covered by their own Australian standards.
What matters when choosing and installing a waterproofing membrane?+
The membrane must suit the surface it covers and how the area is used, such as foot traffic on a deck. Just as important are the details around it: a sound substrate, falls that let water drain, outlets, and sealed edges, upturns and penetrations. Most membrane failures start at those details rather than in the open sheet.
Why does ponding matter on a flat roof?+
Standing water adds load, speeds ageing of the membrane and finds weak points at laps and terminations. A membrane does not create falls; if the roof does not drain, drainage and substrate may need correcting first.
Can a membrane go over a damaged or damp surface?+
Only after the substrate is sound, clean, dry and compatible with the system. Rot, rust, loose fixings and moisture trapped beneath a membrane cause blisters and early failure, so repair and preparation come before coating.
Is waterproofing the same as fixing a roof leak?+
Not always. The entry point must be found first. A membrane is the right answer for a failed flat roof, deck or box-gutter lining, but not for a loose flashing or a failed fastener on a sheet roof.