Facade and roof sealers and cleaners

Water repellency for render, brick, stone and concrete, and washing for facades and roof tiles. On a facade one rule holds without exception: the treatment has to stay vapour-permeable.

This view contains only the products assigned to this surface.

Vapour permeability
A wall releases moisture outwards. A product that closes off vapour diffusion would trap it in the structure.
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

On a facade and on a roof, sealing does one thing: it makes the wall water-repellent, lowering its water uptake. A wall that does not drink rain is slower to grow algae, less prone to salt efflorescence and better at surviving freeze-thaw.

The condition you cannot skip

The treatment has to be vapour-permeable. A wall releases moisture outwards; a product that closes off water-vapour diffusion would trap it in the structure, which is worse than not sealing at all. Every facade product in this category has that property on its data sheet, and where the manufacturer gives diffusion resistance as a figure, we quote it in the technical data.

Order of work

  1. Wash the surface with a cleaner matched to the soiling: algae and moss come off with an alkaline product, efflorescence with an acidic one.
  2. Rinse thoroughly and let the wall dry all the way through. After pressure washing that is usually days, not hours.
  3. Repair joints and cracks. A sealer is not a sealant and will not close a crack.
  4. Mask joinery, glazing and planting at the foot of the wall.
  5. Work upwards, out of direct sun and with a forecast free of rain.

Roof tiles are washed by hand only and on a cool surface - ideally morning or evening. On a warm covering the product evaporates before it can work.

Questions before you choose

Will a facade sealer trap moisture in the wall?

It should not, and that is not its mechanism. Water-repellent products limit the ingress of water from outside while leaving the pores open to vapour diffusion.

What do I do about green growth?

Wash it off first with a product for organic soiling, rinse thoroughly and dry the wall, then seal. Sealing without washing traps the growth under the treatment.

Can I wash only the dirty part of a facade?

We would advise against it. A washed section against an unwashed one stays visible as a lighter patch - the commonest mistake when cleaning facades in spots.

Will sealing improve the insulation of the wall?

We do not claim that, and neither do the manufacturers' data sheets. A sealer acts on the water uptake of the surface, not on heat transfer through the structure.