When selecting a waterproofing solution, one of the most common questions installers and DIYers ask is: “Which substrates can a liquid membrane be applied over?” With the right product and preparation, modern liquid waterproofing membranes like SEMCO Liquid Membrane™ can bond and perform across a wide variety of substrate types for waterproofing wood, concrete, tiles and more.

In this post, we’ll explore:

1. What makes an ideal substrate for liquid membrane
2. The specific substrates SEMCO Liquid Membrane™ supports
3. Key preparation considerations for each substrate
4. Common pitfalls & advice for best results

Why Substrate Compatibility Matters

Liquid membranes are designed to form a seamless, flexible coating that adheres to a substrate and resists water penetration, while being able to stretch, bridge cracks, and cope with slight movement.

The SEMCO Works Liquid Membrane™ is engineered to be applied over a surprisingly broad range of materials, provided correct preparation. It’s s suitable over 15+ substrates including wood, tiles, brick and concrete.

But for this to work:

• The substrate needs to be clean, stable and properly prepped so the membrane can bond to it.
• Any contaminants (oil, dust, coatings) must be removed.
• The substrate must be dry (within allowable moisture limits) so that the membrane can cure properly.

If these conditions aren’t met, adhesion failure, peeling, or incomplete waterproofing may result. Keep reading for a breakdown on the common substrate categories and how our product handles each.

Substrate Types You Can Waterproof with SEMCO Liquid Membrane™

The principal substrate types that Liquid Membrane™ supports in both interior & exterior areas include:

• New or existing concrete
• Cement sheeting / fibre cement board
• Tiles (ceramic / porcelain / mosaic) — waterproofing under new tiles or over existing tiles
• Wood / timber surfaces —
• Asphalt / bituminous substrates
• Metal / aluminium / roofing metal
• WR Board (Water-resistant sheeting / waterproofing board substrates)
• Bricks / masonry / blockwork

If you have more exotic substrates (e.g. existing coatings, plastics, fiberglass, epoxy overlays), a small test panel and compatibility trial would be prudent.

Substrate Preparation: Best Practices

To ensure lasting adhesion and waterproofing, adhere to these best practices:

1. Clean thoroughly

   Use appropriate cleaners — such as our Power Cleaner, Stone Soap, Nu-Lift — and follow our “Prep” guidance (Prep A, B, C, D) for each substrate type, located on our product page.

2. Remove contaminants

   Oils, grease, curing compounds, waxes, coatings — all of these must be removed or reduced to a clean, stable base.

3. Repair and reinforce

   Any cracks wider than ~6 mm should be bridged using fabric reinforcement. Smaller cracks will generally be handled by the elastomeric nature of the membrane.

4. Ensure dryness / moisture control

   Substrates must not be saturated. For most non-submerged uses, residual moisture must be limited (max residual moisture ~3 %).

5. Mask edges / protect adjacent surfaces

   Cover areas not to be coated; remove masking before full cure.

6. Apply in thin, uniform coats

   Multiple thinner coats (e.g. 0.75 mm × 2) are preferable to a single thick coat. Each coat should be allowed to dry sufficiently before reapplication.

7. Curing & protection

   Allow adequate cure time (often 6–7 days for full cure depending on conditions) before exposing to water.

   For trafficable surfaces, the membrane must be sealed with a compatible sealer (e.g. SEMCO Titan Shield Gloss) to protect it.

Common Pitfalls & How to Avoid Them

• Applying over damp substrate → Leads to poor cure or tacky surface
• Skipping cleaning or surface prep steps → Reduces bond strength
• Applying too thick a coat → Traps moisture, prolongs curing, leads to film defects
• Failing to reinforce wide cracks or joints → Stress may cause membrane failure
• Not sealing trafficable membranes → Wear or abrasion can degrade the membrane
• Not testing on unfamiliar substrates → You risk adhesion failure

Summary & Recommendations for Your Project

Liquid membrane waterproofing brings flexibility, seamless adhesion, crack bridging and versatility. With SEMCO Liquid Membrane™, you can confidently waterproof a wide range of substrates — from concrete, tiles, bricks, wood, metal, asphalt and more — so long as proper surface prep and application practices are followed.

If you're planning a particular project (e.g. external balcony, bathroom, roof, pond, planter box) and want guidance on substrate-specific steps or compatibility, our team is happy to answer your questions.