RLA Moisture Seal Primer

Damp concrete, residual moisture, rising damp — these are the project killers that threaten floor and wall finishes. RLA Moisture Seal confronts these challenges directly. It provides a high-performance, hydrostatic-pressure-resistant barrier and primer system, specifically engineered for demanding moisture management applications. Get the right start, even on the toughest substrates.

Why this product exists

RLA Moisture Seal is a high-performance, 2-part water-based epoxy primer and barrier coating system. It handles up to 25 metres (250Kpa) of hydrostatic pressure, specifically designed to prevent moisture and vapour ingress. This is a critical distinction from standard primers or flexible membranes: it builds a robust barrier capable of resisting significant water pressure, not just a surface bond or a flexible layer. It protects overlaid coatings and finishes — such as paints, vinyl, carpet, tiles, timber flooring, and levelling compounds — from blistering, delamination, and efflorescence caused by unmanaged moisture. Beyond surface protection, it forms a negative-side moisture barrier for underground structures, like basements and lift pits, and is suitable for potable water storage.

The numbers that matter

• 2.5 bar (250Kpa / 25 metres) hydrostatic pressure resistance: This is the key performance metric for RLA Moisture Seal. It means the coating can withstand significant water pressure pushing against it, making it ideal for managing rising damp and negative-side waterproofing in basements or retaining walls. Without this capability, moisture would force its way through, causing failures.
• 1.8 g/m²/24 hours water vapour transmission (2 coats @ 200µm DFT): A low water vapour transmission rate means very little moisture vapour can pass through the cured film. This protects moisture-sensitive floor finishes like timber or vinyl from damage, blistering, or delamination, ensuring their longevity and appearance.
• 1:1 mix ratio by volume with 2-hour pot life: The straightforward 1:1 mix ratio simplifies preparation on site, reducing errors. The 2-hour pot life provides ample working time for thorough application, especially across larger areas or when preparing repair mortars, ensuring the product maintains its workability for longer.

What it's like to use

RLA Moisture Seal mixes easily; combine equal parts A and B by volume in a clean pail. Use an electric stirrer for a minimum of 3 minutes to achieve a homogenous consistency, then allow a 5-minute settlement period before application. This ensures full chemical activation and optimal performance. For floors, use a squeegee, stiff nylon broom, or medium/long nap roller. On vertical walls, a medium-long nap roller is recommended. Work the product well into the substrate to ensure optimum absorption and penetration. Regular use of a wet film thickness gauge during application ensures the specified film thickness is achieved for the desired barrier performance. All equipment cleans up immediately with soapy water. Dried product requires mechanical removal.

For overlaying finishes such as levelling compounds, tiling, or screeds, the second coat of Moisture Seal requires sand seeding. Broadcast fine, dry sand into the wet second coat at 750g/m² to achieve at least 90% coverage. Once dry, sweep or vacuum away excess sand to create a mechanical key for adhesion.

Where this product excels

• Priming damp or 'green' concrete: It can be applied to concrete that is still curing or retains significant residual moisture, providing a critical barrier to protect subsequent finishes from moisture-related failures. This accelerates project timelines where typical concrete drying times would cause delays.
• Negative-side waterproofing: For structures like basements, lift pits, and retaining walls, it prevents moisture ingress and seepage from the negative side, where direct external waterproofing isn't feasible.
• Under floor and wall finishes: This product protects decorative floor and wall finishes including paints, vinyl, carpet, tiles, timber, and levelling compounds from damage, blistering, and delamination caused by moisture vapour and rising damp. It acts as a robust sub-surface defence.
• Potable water storage: Formulated to comply with AS 4020, it is suitable for lining potable water tanks and reservoirs, providing a safe and effective waterproof coating for water in human contact.

How it fits in a real system

RLA Moisture Seal consistently appears as the crucial first step in systems, particularly for Wet Wall and Floor to Non-Habitable Areas. Here, it functions as the primary primer and vapour barrier coating. Its ability to be applied to damp or 'green' concrete allows for a faster start to subsequent layers. For example, it frequently precedes self-levelling compounds such as Trulevel Fine Finish, forming the foundation for a smooth, moisture-protected surface before final floor coverings are installed. This early-stage application ensures the entire system's integrity by managing moisture from the ground up.

Choose this when

• When applying finishes over damp or 'green' concrete: Its compatibility with damp substrates and strong barrier properties prevent moisture-related failures like blistering or delamination in subsequently applied membranes, adhesives, or floor coverings.
• For negative-side moisture protection: When waterproofing basements, lift pits, or retaining walls from the internal face, its hydrostatic pressure resistance stops water ingress where external access is impossible.
• When preventing rising damp and efflorescence: As a robust barrier coating, it protects decorative finishes from moisture wicking up through the substrate, preserving their appearance and longevity.
• As a primer for RLA membrane systems: It provides outstanding adhesion for RLA's range of membranes, coatings, adhesives, and levelling compounds, ensuring system compatibility and bond strength.

Don't use this when

• Not for: Application during rain or when rain is imminent, or when surface or ambient temperatures are outside the 10ºC to 35ºC range. Cure rates slow dramatically below 10ºC.
• Not for: Application over active structural water leaks. These require prior treatment with a suitable hydraulic setting cement/water plug before RLA Moisture Seal can be applied.
• Not for: Use as a standalone trafficable wearing surface or as a finished coating subject to permanent UV exposure. It must be covered by floor toppings, coatings, or conventional coverings.
• Not for: Application to steel/metal surfaces, as it can contribute to corrosion.

Related products

• Everflex Multi-Prime Waterproofing Membrane
• RLA Safe2O Waterproofing Membrane