Waterproofing Membranes

Waterproofing Membranes for Roofs, Basements, Wet rooms & Balconies – Liquid, Sheet & Cementitious Systems

Waterproofing membranes are essential building supplies in safeguarding buildings from the damage caused by water infiltration. They act as protective layers that block moisture from penetrating porous substrates such as concrete, masonry, render, and cement screeds. By forming a continuous, impermeable layer, these membranes help protect structural integrity, prevent mould and damp development, and extend the life of surrounding finishes and fixtures.

Shop high-performance options for both positive and negative side waterproofing, with flexible formulations that bridge small cracks and accommodate building movement. Many products are UV-stable, foot-traffic tolerant, or suitable for use under tiles, screeds, and insulation systems - making them ideal for everything from rooftop terraces to internal wet rooms and plant rooms.

Liquid membranes offer seamless application over irregular surfaces, while self-adhesive sheets and cementitious coatings provide durable protection where mechanical adhesion or fast recoat times are required. Each membrane type is designed to work with compatible primers, tapes, and sealants, creating a full waterproofing system that resists weather, pressure, and long-term wear.

With a variety of pack sizes, application methods, and drying speeds available, our waterproofing membranes are suited to both professional contractors and experienced DIYers. Browse our full range of waerproofing membranes and supplies to find the right product for your specific surface and environment, and protect your project from water damage with confidence.

FAQs – Waterproofing Membranes

What’s the difference between positive and negative side waterproofing?

Positive side waterproofing is applied to the surface facing water (e.g. the exterior of a basement wall), while negative side waterproofing is applied to the interior face to block water that has already penetrated. Product choice depends on site access and the direction of water pressure. Not all membranes are rated for negative pressure, so check specifications carefully.

Can I apply waterproofing membranes without a primer?

In most cases, a primer is recommended to stabilise the substrate, reduce absorbency, and improve adhesion. Some liquid membranes are self-priming on clean, sound surfaces, but high-absorbency or dusty areas benefit from a dedicated primer or pre-treatment layer. Always consult the product datasheet for guidance on preparation.

How do I reinforce corners or cracks when using a membrane?

Corners, joints, cracks, and upstands should be reinforced using compatible detailing tape, fleece, or mesh. These materials are embedded into the first coat of membrane and then overcoated to ensure flexibility and strength where movement is most likely. This prevents splitting or leaking in critical areas.

Are all waterproofing membranes suitable for tiling over?

Not all membranes are tile-friendly, but many are designed to accept tile adhesives once cured. Look for membranes described as tile-backer compatible or suitable for use beneath ceramic and porcelain finishes. Cementitious membranes and some acrylic or polyurethane liquids are often used in bathrooms and wet rooms beneath tiled surfaces.

How long do waterproofing membranes take to dry before overcoating?

Drying times vary depending on product type, temperature, humidity, and substrate porosity. Some fast-curing membranes are touch dry within 1–2 hours and ready to recoat the same day, while others may require overnight drying. Always check the manufacturer’s guidelines for minimum and maximum overcoating windows.