Everbuild 503 SBR Bond is a latex-based bonding agent and cement admixture that improves water resistance, flexibility and long-term durability in renders, screeds and repairs. Ideal for damp and wet areas.
Everbuild 503 SBR Bonding Agent is a latex-based liquid used across plastering, screeding and general building work where standard mixes just won’t cut it. The 5L tub is the go-to size for trade use — enough for a decent run of work without lugging around the bigger drums. Whether you’re using it as a bonding slurry before a scratch coat or blending it into a floor screed mix, this is one of those products that quietly earns its place on the van.
SBR stands for Styrene Butadiene Rubber, which sounds more complicated than it is. In practice, it’s a polymer that works its way through the cement matrix as it cures, forming a reinforcing web that makes the finished mix tougher, more flexible and considerably more water resistant than plain cement alone. On a building site, that means fewer cracks, better adhesion to tricky substrates, and a render or screed that isn’t going to fail the moment it sees a bit of moisture.
Where Everbuild 503 SBR Bonding Gets Used
The most common use is as a bonding agent — brush it onto a prepared substrate, let it go tacky, then apply your render or plaster on top. It gives the new material something to grip, which matters a lot on smooth or low-suction surfaces like painted concrete, engineering brick or old glazed tiles. It’s also widely used mixed directly into cement and sand to produce a modified screed or repair mortar with improved adhesion and durability.
Damp and Water-Exposed Areas
This is where Everbuild 5L SBR bonding really earns its keep. Basement tanking systems, wet rooms, pool surrounds, drainage channels and any external render that’s going to face the British weather — SBR modified mixes hold up far better than unmodified cement. It won’t do the whole waterproofing job on its own, but as part of a properly specified system it makes a real difference to longevity.
At 5L, you’re getting a practical, manageable quantity that suits most single-job or day’s work scenarios. Mix ratios vary depending on the application, but the bottle gives clear guidance and most plasterers and groundworkers will already know the ratios off the top of their heads anyway.
Pro Tip: When using SBR as a bonding slurry, apply it in a thin, even coat and wait until it goes tacky before applying your render or plaster — if it dries out completely you'll lose the bond, so time it right on hot or windy days.
SBR bonding agent is used daily by plasterers, groundworkers, tilers and general builders. It goes into render mixes on external walls, modified screeds on floors, repair mortars for concrete structures, and as a primer coat on low-suction or previously painted substrates. It's particularly common in wet environments where standard cementitious mixes struggle, including basements, shower areas, utility rooms and external applications exposed to standing water or driving rain.
Best For
Bonding slurry before rendering or plastering
SBR-modified floor screeds
Cement-based repair mortars
Wet rooms and damp areas
Basement and external render systems
Concrete repair and patching
Compatible Surfaces
Concrete and block
Brick and engineering brick
Existing render and plaster
Low-suction or smooth substrates
Sand and cement substrates
Key Properties
Latex-based polymer formula
Improves water resistance of cement mixes
Increases flexibility and crack resistance
Enhances adhesion to difficult substrates
Suitable for continuous water contact areas
Use as admixture or bonding primer
Not suitable for: Not suitable as a standalone waterproof membrane — it must be used as part of a properly specified cementitious system. Not recommended for use on substrates contaminated with grease, oil or release agents without thorough preparation first.
As a bonding agent, dilute with water at roughly 1 part SBR to 1 part water, brush generously onto the prepared substrate and allow to become tacky before applying render or plaster. The surface must be clean, sound and free from dust, grease and loose material before application.
As a cement admixture, replace part of the gauging water with undiluted or diluted SBR depending on the application. Typical ratios for a modified screed are around 1 part SBR to 3 to 4 parts water added to the dry mix, though this varies by job. Always follow the guidance on the container and check compatibility with your sand and cement specification before mixing large batches.
Clean the substrate thoroughly, removing dust, loose material, grease and any previous coatings that may affect adhesion
For use as a bonding agent, dilute SBR approximately 1:1 with clean water
Apply the diluted SBR slurry evenly to the substrate using a brush, ensuring full coverage
Allow the coat to become tacky before applying render, plaster or mortar — do not allow it to dry out completely
For use as an admixture, substitute part of the gauging water with SBR at the appropriate ratio for your mix
Mix the SBR-modified mortar or screed to a consistent, workable consistency and apply in the normal way
Keep freshly applied work protected from frost and rapid drying during the curing period
Can I use Everbuild 503 SBR on its own as a waterproof coating?
No. SBR bonding agent is not a standalone waterproof membrane. It significantly improves the water resistance of cement-based mixes when used as an admixture or bonding agent, but it needs to be part of a full cementitious system to provide reliable waterproofing. For tanking or wet room work, use it in conjunction with a properly specified waterproof render or slurry system.
What mix ratio should I use when adding SBR to a floor screed?
A common starting point is 1 part SBR to 3 or 4 parts water as a replacement for the gauging water in your screed mix, but this varies depending on the required performance and the specific application. Always refer to the guidance printed on the container, and do a trial mix before committing to a large pour.
Everbuild 503 SBR Bond is a Styrene Butadiene Rubber latex emulsion that, when incorporated into or applied alongside cementitious mixes, forms a reinforcing polymer network within the set matrix. This increases the tensile and flexural strength of the cured material, reduces water permeability and improves adhesion to a wide range of substrates. Suitable for applications in continuous water contact conditions.
Brand
Everbuild
Product Code
503
Size
5L
Base
Latex (Styrene Butadiene Rubber emulsion)
Application Method
Brush applied bonding agent or cement admixture
Water Resistance
Suitable for areas subject to continuous water contact
Colour
White liquid (milky)
Product Type
Plastering Adhesives
Size
5
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