Larsen Waterproof Tanking Membrane is a ready-to-use, solvent-free, brush-applied elastomeric sealing compound designed for professional-grade waterproofing beneath tiled surfaces in wet rooms, shower enclosures and splash zones. Applied directly to the substrate before tiling, it forms a continuous, flexible waterproof membrane that protects the structure behind from moisture ingress.

The single-pack formulation goes on straight from the tub — no mixing, no priming, no fuss. Brush or roller applied in two coats, it dries to a tough rubber-like film that bonds tightly to concrete, sand/cement render, plasterboard and tile backer boards. Once cured, it accepts cement-based tile adhesives directly without any further preparation, so the tiler can crack on the same day.

For full wetroom protection, use alongside Larsen self-adhesive tanking tape at every floor-to-wall junction, internal corner and pipe penetration — the points where water failure almost always starts. The combination gives a fully sealed, continuous waterproof envelope that meets the standards expected on domestic and commercial wetroom installations.

Key features

• Ready mixed, brush applied — no on-site mixing required
• Solvent free, low odour — safe for indoor use in occupied properties
• Remains permanently flexible once cured — absorbs minor structural movement
• Bonds to concrete, screed, render, plasterboard and tile backer board
• Compatible with all standard cement-based tile adhesives
• Use with Larsen tanking tape at joints, corners and pipe penetrations
• Two-coat application — typical coverage 1.5m² per litre per coat

Suitable for

• Wetroom and walk-in shower waterproofing prior to tiling
• Bathroom splash zones around baths, basins and shower trays
• Domestic utility rooms and downstairs WCs subject to occasional water exposure
• Commercial shower facilities, gym and changing-room installations
• Tile backer board joint sealing as part of a full wetroom build-up

Part of the full Larsen wetroom system — pair with self-adhesive tanking tape, primers and flexible tile adhesives from the same range for a fully compatible installation.