Facade and roof sealers and cleaners

Water repellency for render, brick, stone and concrete, plus washing for facades and roof tiles. Facade sealers leave the wall vapour-permeable, so it still releases moisture.

Vapour permeability
A wall releases moisture outwards. A product that closed off vapour diffusion would trap it in the structure - which is worse than not sealing at all.
Wash first
A sealer applied over live algae seals them in. The cleaner comes before the sealer, not after.
Direction of work
Upwards. Product running down a dry wall leaves a mark that cannot be evened out.

25 products

Guides

Before you choose: how to pick the right product, prepare the surface and what to expect once it is on.

On a facade or a roof, sealing does one thing: it makes the masonry water-repellent, lowering how much water it takes up. A wall that does not soak up rain dries faster, shows salt efflorescence less often and copes better with freeze-thaw.

Facade cleaner

Green algae growth and atmospheric dirt come off with the alkaline C-11E. It works on silicone, acrylic, silicate and mineral renders, on facade paints, brick, clinker, stone and concrete. Dampen the wall with clean water, apply the solution and rinse it off from top to bottom after 2-3 minutes. With a pressure washer, 10-20 ml of product per litre of water is enough - the jet is there to rinse away what the cleaner has loosened, not to strip the render. Wash the whole face, because a cleaned section stays visible as a lighter patch. The guide cleaning algae off a facade takes you through it step by step.

Moss and algae removers for facades and roofs, and sealers for the cleaned surface, are on the moss and algae removers page.

Facade sealer matched to the substrate

A facade sealer limits the ingress of water from outside while the wall still releases water vapour. Choose it by what the wall is made of:

  • Brick and clinker - the clear siloxane VC-1. More in the brick and clinker section.
  • Sandstone - VP-1, which limits the cycle of soaking and freezing that is the main way this stone breaks down.
  • Architectural concrete - the clear VB-1.
  • Several substrates at once - the clear ImperGuard Ultra 4 in 1 for facades, roofs and paving, about 8 m² per litre.
  • Old render, brick or stone to refresh - EH-16, which gently deepens the colour.

A deepened colour cannot be undone, so on a wall facing the street start with a test. We go further into the choice in the guide facade and roof sealers.

Roof tiles

Wash clay and concrete roof tiles with C-11D on a cool surface, ideally in the morning or evening, and protect them with VD-1, which forms no film and leaves the roof looking the same. Details are in the roof tiles section.

Order of work

  1. Wash the surface and rinse it clean.
  2. Let the wall dry right through. After pressure washing that usually takes days, not hours.
  3. Repair joints and cracks. A sealer is not a sealant and will not close a crack.
  4. Protect window frames, glass and plants by the wall.
  5. Work from the bottom up, out of direct sun and with no rain forecast.

Questions before you choose

Will a facade sealer trap moisture in the wall?

No. Water-repellent products limit the ingress of water from outside while the pores stay open to vapour diffusion - the wall still releases moisture outwards. Where a product's diffusion resistance is given as a figure, it is in its technical data.

What do I do about green growth?

Wash the wall with a product for organic soiling, rinse it thoroughly and let it dry. Seal only a clean, dry wall.

Can I wash only the dirty part of a facade?

Better not. A washed section against an unwashed one stays visible as a lighter patch. Wash the whole face of the wall.

Will sealing improve the insulation of the wall?

No - a sealer is not thermal insulation. It acts on the water uptake of the surface, not on heat transfer through the structure.