RLA Foam Filler

For fixing and insulating door and window frames, filling wall penetrations, and sealing plumbing cavities, RLA Foam Filler provides an expanding polyurethane barrier that seals out draft, noise, moisture, and dust. It adheres to common construction substrates including timber, brick, concrete, galvanised steel, aluminium, glass, compressed cement-sheet, and plasterboard.

How it works

RLA Foam Filler is a moisture-curing polyurethane foam that expands up to 45 times its original liquid volume to fill deep cavities and irregular gaps. As it expands, it conforms closely to the surrounding substrate to create an airtight, mould-proof, and water-resistant seal with a water absorption rating of only 1% by volume. Once fully cured, the beige foam can be cut, sanded, and painted to match the surrounding wall profile. The ozone-friendly propellant system contains no hazardous gases, and the delivery valve allows the canister to be reused after partial applications.

Numbers that matter

• 45x expansion: Fills large, deep cavities and wall penetrations efficiently from a single 500ml can, yielding between 30 and 45 litres of cured foam.
• 15 to 30 minutes skin time: Quick surface skinning at 23°C and 50% relative humidity prevents sagging in vertical joints.
• 8 hours to cut, sand, or paint: Reaches sufficient structural density within 8 hours to be worked back to the substrate profile.
• -40°C to 80°C temperature resistance: Maintains its insulating barrier behind wall penetrations, electrical outlets, and water pipes under high thermal exposure.
• 0.03MPa compressive strength: Flexible, low-density foam (22 ± 3kg/m³) that seals without distorting lightweight window or door frames.

Where to use it

• Fixing, sealing, and insulating around timber and aluminium door and window frames.
• Filling service penetrations in brickwork, concrete, and plasterboard walls.
• Insulating plumbing pipe penetrations and electrical outlet back-boxes.
• Sealing expansion joints and deep cavities in compressed cement-sheet assemblies.

How to apply

Ensure all surfaces are clean and free from loose material, dust, grease, and existing coatings. Remove structurally unsound layers mechanically. Lightly dampen the substrate with a water mist before application to accelerate the moisture-cure reaction and improve adhesion. Shake the can vigorously 15 to 20 times, screw the application tube onto the trigger valve, invert the can, and apply pressure to the trigger. Fill cavities to only one third of their total volume, allowing room for the foam to expand. Fill larger cavities in stages, allowing each layer to expand before applying the next.

Limitations

• Do not apply when ambient or surface temperatures are below 5°C or above 30°C. Cold conditions will decrease the final yield and lengthen the curing window.
• Not suitable as a load-bearing structural material.
• Do not use in areas subject to foot or vehicular traffic.
• Do not use in permanently immersed environments.
• Cured foam will discolour and degrade under ultraviolet light. Outdoor applications must be painted or coated to protect the foam from UV exposure.