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How to seal render with a breathable sealer

how to seal render with a breathable sealer

How to seal render with a breathable sealer

This ‘how to’ guide explains how to seal exterior render & masonry with Floorseal Render & Masonry Sealer.

Floorseal Render & Masonry Sealer is a breathable sealer which creates a waterproof & stain-resistant surface. The sealer is resistant to UV light and also resists the effects of pollution.

To view the product page for Floorseal Render & Masonry Sealer please click on the product title above highlighted in blue.

How to protect external render and masonry surfaces with a breathable sealer

What kind of performance should I expect from a render sealer?

The characteristics of a quality render sealing solution are – resistance to rainwater, organic growth, carbon deposits & UV light. The sealer should be non-film forming, therefore the render is sealed without a surface coating or skin being formed. You should expect a lifespan of approximately 10 years from an impregnating sealer.

Ideally, the render should retain a surface capable of allowing moisture vapour transmission. This will occur if the polymers used to seal the render penetrate the surface sealing the surface from within.

An impregnating render sealer will not trap moisture as it does not form a film or coating. Therefore, the render (or masonry) will still allow moisture vapour transmission after being sealed.

Please note: Render sealers are not for filling cracks or holes in the render. They are for making the render moisture repelling. Thus prevent rainwater/damp penetration & inhibiting organic growth.

Floorseal Render & Masonry Sealer is perfect for sealing render & masonry as it is resistant to rainwater, UV light, and carbon deposits & also inhibits organic growth. The surface is sealed and still allows vapour transmission without a film or skin being formed. This product is a water-based impregnating sealer, free from solvents & VOCs, and dries rapidly.

Importantly Floorseal Render & Masonry Sealer is non-film forming so the sealer actually becomes meshed into the surface sealing it from within. The treated surface will still be fully breathable after it has been sealed.

This breathable sealer is suitable for all porous exterior concretes, cement-based renders, general masonry, bricks & natural stone. It is a form of impregnating sealer, which is resistant to UV light, so has a lifespan of 10 years+.

Render in the UK can also be called 'Pebbledash'

How do I apply Floorseal Render & Masonry Sealer?

We recommend applying this product via a low-pressure pump-up sprayer or roller. The sealer should be applied to the surface when it is dry, allowing it to soak in.

When applying impregnating sealer, you should always remove any excess product. Excess removal can be carried out with dry absorbent rollers or microfibre cloths after approximately 20 – 30 minutes.

Apply the sealer so that the render becomes saturated. Much of the sealer will be drawn into the pores of the render by capillary action. Once this has occurred any of the solution left on the surface is an excess. It is this excess sealer which should be removed (where present).

Excess sealer may not be present over the entire surface, possibly just in jointing material or on very rough surfaces. Do not allow any sealer to simply sit on the surface and dry.

Once the initial application has been applied (and any excess removed) apply the sealer again (lightly) approximately 40 minutes later. Again, all excess should be removed and the surface left to dry. Dense renders may only require one coat of product.

When removing excess render sealer, we recommend waiting approximately 20 – 30 minutes before doing so. Obviously, air temperatures can affect this timescale. Carry out a small test area to gain an optimal timing for excess removal. You may find no excess is present on very porous surfaces such as concretes, natural stone or porous cement-based renders.

Coverage Rates

Render & Masonry Sealer will cover approximately 5m2 per litre. 10m2 per litre can be achieved on dense surfaces. Please be aware that coverage rates always vary depending on the individual porosity of the surface being sealed.

A 5-litre container will cover approximately 25m2 of surface area when applied correctly. Please adapt this coverage rate based on porosity.

In conclusion

Floorseal Render & Masonry Sealer is resistant to rainwater, UV light, and carbon deposits, it inhibits organic growth and allows the surface to breathe. This product is a water-based sealer, free from solvents & VOCs, and dries rapidly.

This sealer can be applied to concrete, porous cement-based renders, general porous masonry, bricks and natural stone.

Apply with a sprayer, roller or brush removing all excess product after approximately 20 – 30 minutes. Apply a 2nd light coat around 40 minutes after the 1st application. Very dense surfaces may only require one coat.

We recommend spraying the surface with a fungicide such as Green Remover Concentrate before applying any sealer – ideally allow 24 hours drying time before applying the sealer.

Suitable for K-rend, general sand & cement renders & monocouche renders.

Do not overpaint Floorseal Render & Masonry Sealer – This product is a stand alone sealer. It is not a base to which paint should (or can) be applied. If Render & Masonry Sealer is to be applied to previously painted renders the paint would need to be porous (or have become porous) to accept the sealer. If wish to seal a surface prior to painting please use Floorseal Stabilising Solution, see below –

Floorseal Stabilising Solution is an overpaintable primer which can be applied prior to painting your render with a masonry paint. This product is suitable for application in one coat. Stabilsing Solution is a water-based primer which helps paint adhere to softer friable surfaces.

Apply in a single coat (to dry render) and allow at least 4 hours before overpainting. This type of sealer is perfect for creating a base which can then be overpainted with an exterior masonry paint. Floorseal Stabilising Solution is suitable for use on any porous render. Please pre-treat the surface with a fungide such as Floorseal Green Remover Concentrate as above. 

Further Information

Please Click Here to view all our products & accessories for cleaning and sealing render and our handy associated ‘how to’ cleaning and sealing guides. We recommend cleaning your surface before sealing work is carried out (unless the surface is new).

The information included in this article is not exhaustive. If you need further information please contact Floorseal on (01484) 861461 or email us our web address is