Roof coating for concrete and clay tile roofs in Northern Germany, Sweden and Denmark

A roof coating is a multi-layer protective finish for pitched roofs made of concrete tiles, clay tiles or fibre cement. It closes a surface that weather has made porous, reduces water absorption and gives the roof a uniform colour. Applied professionally, it typically lasts 15–20 years.

Concrete tiles are coated most often. Their factory colour layer wears away over the years, leaving a rough, absorbent surface where algae and moss settle quickly and which stays wet long after rain. This is exactly where a coating helps.

Realistic expectations matter. A coating protects and preserves a roof covering that is still sound. It does not seal a leaking roof, does not replace insulation and does not repair broken tiles, battens or a damaged underlay.

A roof coating is worth considering when the tiles are firm and the roof is watertight, but the surface has visibly aged. Typical signs include:

In Germany we have coated, among others, the roof of a detached house in Rostock in anthracite and a bungalow roof in red. Photos of these projects show how much a coating can change the look of a house. Whether your roof is a candidate, we can usually judge from a few clear photos.

Coating a roof is a sequence of steps, each building on the one before. Durability is decided mainly by the preparation – the visible colour is only the final layer.

Why several coats? A single coat is too thin and does not reliably cover pores and edges. Only several coats with enough drying time in between create an even layer without weak spots where water could get in. The primer underneath acts as the bonding agent between the absorbent tile and the coating.

The coating itself usually takes one to three days, depending on roof size. Because coatings may only be applied in suitable weather – dry, not too cold, no rain forecast – we plan with a buffer. For assignments in Sweden and Denmark we set a time window together with you, since travel and weather both have to fit.

Suitable materials are concrete tiles, clay tiles and asbestos-free fibre cement. With engobed or glazed clay tiles we check carefully whether a coating is worthwhile, because their surface is already fairly closed and offers less grip.

Asbestos is a firm limit. Asbestos-containing sheets should only be handled by licensed specialist firms, and in Germany uncoated asbestos cement roofs may not be coated at all. Crumbling tiles, many broken tiles, damaged battens or a leaking underlay cannot be fixed with a coating. Solar panels must be removed before the area beneath them can be coated – please clarify this with your installer.

Popular roof colours are red, dark red and anthracite. Dark shades look modern but heat up more in the sun than lighter ones. Local planning rules can restrict roof colours, so check with your municipality before deciding.

A coating is the right choice when the roof covering is sound and watertight and mainly the surface has suffered. It keeps the existing roof, improves its appearance and makes it harder for moss to take hold again – without tearing off, disposing of and replacing the tiles.

A roofer is needed when water comes through, many tiles are broken or brittle, the battens or underlay are damaged, or external insulation is planned anyway. In those cases a coating would only be cosmetic, and we will say so even if it means we do not get the job.

After coating, little maintenance is needed: keep gutters clear, cut back overhanging branches and look at the roof from the ground now and then, especially after storms.