FAQs About Liquid Waterproofing Membranes

Liquid waterproofing membranes are a powerful way to defend surfaces against moisture and water ingress. Applied like paint, these flexible coatings form a seamless, impenetrable layer that protects the structure beneath. They're also excellent for patching existing damage and preventing future cracking. This guide breaks down everything you need to know about these liquid-based waterproofing membranes.

What exactly is a liquid membrane?

Liquid waterproofing is a method of creating a waterproof barrier by applying a liquid compound directly onto a surface. Once it dries or cures, it forms a seamless yet flexible membrane that prevents water from penetrating the underlying material. Unlike roll-on sheet systems, liquid membranes adapt effortlessly to complex surfaces. They fill in gaps around penetrations, joints, and uneven shapes — creating an impenetrable barrier where sheet systems might fail.

What is the best liquid waterproofing membrane to use?

Among the top performers in this category is SEMCOWorks’s Liquid Membrane™ — a premixed, water-based, multi-purpose solution that delivers both waterproofing and crack bridging. It's a ready-to-use, single-part formula that combines an elastomeric fluid with high-adhesion copolymers to create a tough, flexible coating that blocks water and helps surfaces resist cracks and movement.

Liquid Membrane™ has been used across countless applications, from waterproofing foundations to rejuvenating old floors and sealing balconies, bathrooms, or timber decks.

Benefits of SEMCOWorks Liquid Membrane™:

• Will remain pliable and elastic up to 13 times its length (1300% elongation) to bridge cracks and withstand substrate movement
• Can be painted over with water-based paints to colour match surroundings
• Can be applied in a semi-clear or colour finish as the UV-resistant top coat for surfaces like timber, concrete, bricks and more
• Conforms to all standards for internal and external waterproofing.
• Easy to apply DIY with a roller, brush, or spray gun

Where can liquid membranes be used?

Liquid membranes are incredibly versatile. They’re designed for use over a wide variety of substrates and surfaces, ideal for both indoor and outdoor environments.

Typical uses include:

• Primary waterproofing of concrete, timber, balconies, and wet areas
• Surface preparation before finishing with materials like tiles, microcement, or stone
• Restoring cracked or porous surfaces
• Sealing rooftops, external cladding, and high-moisture zones

Compatible surfaces include:

Concrete, wood, MDF, tiles, render, stone, plaster, bricks, asphalt, Villaboard, fibre cement sheeting, metal, aluminium, and more.

How is it applied?

SEMCOWorks Liquid Membrane™ is designed for simplicity. It can be applied with a roller, brush, or spray gun in just two coats. The surface prep and method may vary depending on your substrate, but the process is DIY-friendly and professional-grade.

It can also be left exposed in select colours, painted over, or covered with other finishes.

How long does it last?

When properly applied, a liquid waterproofing membrane should last 10 years or more. Its long-term performance depends on factors like exposure, foot traffic, and how well the substrate was prepared. Our version includes a 5-year limited warranty (standard) and 10-year warranty on non-traffic areas.

How does SEMCOWorks compare to other formulas?

Compared to rubber and silicone based membranes, ours features a hybrid elastomer blend that offers superior performance across key areas. Its standout feature is active adhesion, meaning it bonds directly to most surfaces without the need for primer.

Another thing setting SEMCOWorks apart is its industry-leading flexibility — it can stretch up to 1300% before breaking. This is significantly higher than many alternatives that typically cap around 800%.

And Liquid Membrane dries faster too, allowing two coats to be applied in a single day with drying times as low as 45 minutes, whereas rubber and silicone systems typically take longer to cure. Additionally, it's UV-stable, low-VOC, and safe for negative side waterproofing.

Other advantages:

• Straightforward application: No mixing or priming required. Just open the bucket and apply with a roller, sprayer or brush.
• Multi-surface compatibility: From concrete and MDF to metal and tiles, this product adheres to over 20 different materials.
• Superior technology: Low VOC and breathable, the membrane prevents trapped moisture while still forming a watertight layer. The advanced polymer chemistry provides crack-bridging flexibility and high durability under load.

How affordable is it?

A little goes a long way with SEMCO Liquid Membrane™. Each litre provides 2-3m2 of coverage at 2 coats (0.75mm each coat). A single 18.9L bucket of SEMCO Liquid Membrane™ is priced at $601, which covers 50–60 sqm in two coats. On the lower end of that range, that works out to just $12 per square metre.

Where can I buy it?

SEMCO Liquid Membrane™ is available from our website only, shipped across Australia with fast delivery. You can also pick it up directly from our Melbourne warehouse.

Is your liquid membrane suitable for bathrooms and showers?

Definitely. It’s a go-to for waterproofing bathrooms and wet rooms, particularly when preparing surfaces for finishes like tiles, microcement/render, or natural stone. It adheres well to cement board, old tiles, and other common substrates for resurfacing. If you’re a surfacing professional — like a tiler or renderer — it’s a must-have.

Can you use it on wood?

Yes, it can be applied to MDF and timber surfaces as either a final coat or as a base for other finishes. To prevent movement and cracking at joints, we recommend reinforcing with mesh or fabric. This technique is often used for custom furniture, sinks, or feature walls with wood substrates.

Can Liquid Membrane™ be used to repair concrete?

Liquid Membrane™ is an ideal solution for sealing and bridging cracks in worn concrete (up to 6mm). It allows you to restore damaged slabs without demolition — just stabilise and overlay with a new finish.