APP Membrane vs Liquid Waterproofing: Which Is Right for Your Roof?

When clients ask us to waterproof a roof, the first real decision is the system: a torch-applied APP membrane or a liquid-applied coating. Both work — but they shine in different situations.

APP membrane

APP (Atactic Polypropylene) membrane is a thick, factory-made sheet that’s torch-fused onto the prepared surface to form a tough, continuous barrier.

Best for:

• Large, flat terraces and exposed roofs
• Surfaces that take foot traffic (with a protective layer like brick bat coba)
• Situations needing maximum mechanical durability

The trade-off is that it needs skilled application and clean detailing at joints and upstands.

Liquid-applied waterproofing

Liquid membranes (polymer-modified cementitious or PU coatings) are brushed or sprayed on and cure into a seamless film.

Best for:

• Complex shapes, many penetrations, or tight corners
• Bathrooms, sunken areas and water tanks
• Adding a flexible top layer over other systems

They’re seamless and easy to detail around obstacles, but generally thinner than a membrane.

How we choose

In practice, the best result often combines both: a membrane base with a thermal/liquid top coat for heat reflection and an extra waterproof layer. The right answer depends on your roof’s size, traffic, slope and budget — which is exactly what we assess on site.

See the full terrace waterproofing system, or talk to our expert for a recommendation tailored to your roof.