Clay roof tiles should be cleaned gently: loose moss lifted off by hand, then a low-pressure soft wash and a biocide. Never jet wash clay. It’s softer than concrete, and pressure can erode the surface, chip edges and drive water under the tiles. Old lichen should be killed and left to weather off.
Why is clay different from concrete?
Clay tiles are fired clay, much like a brick, and their surface is softer and more porous than a concrete tile. Older handmade clay tiles are softer still, and every one is slightly different. That surface, and the colour that comes with it, is what makes a clay roof look the way it does. Lose it, and you can’t put it back.
Which homes in Essex have clay tiles?
- Older houses in historic towns such as Saffron Walden, Maldon, Colchester and Coggeshall, often handmade plain tiles.
- Many 1920s and 1930s houses, including bay-fronted semis in towns like Billericay, Rayleigh and Southend.
- Larger detached homes in places like Brentwood, Shenfield and Hutton, often with hipped roofs and dormers.
- Some new homes, which use machine-made clay tiles.
Why shouldn’t clay be pressure washed?
High pressure erodes the fired surface of the tile. On an old tile that can mean pitting, flaking and lost colour. It can also chip the edges and nibs of plain tiles, wash out mortar at the ridges and verges, and force water up between the overlapping tiles into the battens and felt. Moss also returns faster on a tile that has been roughened.
How do we clean a clay roof?
- Look first. We check for slipped or broken tiles and loose ridges before anything else. Damage gets reported, not cleaned over.
- Hand clear. Loose and thick moss is lifted off by hand and kept off the ground.
- Soft wash. A cleaning solution goes on at low pressure to kill algae, lichen and moss roots.
- Biocide finish. It keeps working for months so growth is slow to return.
- Tidy. Moss and debris are cleared from the gutters and ground.
What about lichen on old clay?
Old clay roofs often carry decades of lichen. It’s killed on the day, then fades and washes off with the rain over the following months. We don’t scrape it, because lichen grips the surface so tightly that scraping takes the face of the tile with it. There’s more in our post on lichen on roofs.
Will the roof look like new?
It will look clean, and the warm colour of the clay will show again. It won’t look brand new, and it shouldn’t: part of the appeal of a clay roof is its weathered, varied colour. A soft wash keeps that character; a jet wash can leave it patchy.
Can clay tiles be walked on?
As little as possible. Clay tiles, especially old plain tiles, crack easily underfoot. We plan access so we can reach each part of the roof without standing on the tiles wherever we can, and we’ll explain how when we quote.
What if my clay roof is on a listed building?
Check with your council’s conservation officer before any work. Gentle cleaning is often fine, but they may have advice on methods or timing. Our post on roof cleaning on listed buildings in Essex covers this.
Should clay tiles be coated after cleaning?
Almost never. A clay roof’s colour and texture is its point, and a sound clay roof doesn’t need a coating to protect it. More on that in is a roof coating worth it?
What is the difference between plain tiles and pantiles?
Plain tiles are small, flat clay tiles laid in overlapping courses, the classic look of older Essex houses. Pantiles are larger, S-shaped tiles, more common in East Anglia on cottages and outbuildings. Both are cleaned the same gentle way. Pantile roofs often have mortar bedding at the edges, which pressure washing can wash out.
Why does moss grow so well on some clay roofs?
Old clay is porous. It holds moisture longer than a dense new tile, and its slightly rough, weathered face gives moss and lichen something to hold. Add shade from trees and you have ideal conditions. A biocide finish slows that cycle right down.
Can broken clay tiles be matched?
Often, from reclaimed tiles of the same type and age, but that’s a roofer’s job. If we find broken or slipped tiles during a clean, we tell you and leave the repair to someone who specialises in it.
Why do clay tiles sometimes look patchy after cleaning?
Old clay tiles were never one colour. Handmade tiles vary from tile to tile, and replacements added over the years may come from different batches or reclaimed stock. Under moss, that variety is hidden; once the roof is clean, it shows again. That’s the character of a clay roof, not a sign of a poor clean.
Do new clay tiles need cleaning?
Rarely, for the first years. If algae appears on a shaded slope, a treatment on its own is usually enough.
In short
- Clay is soft: hand clearing and low pressure only.
- Lichen is killed and left to weather off, never scraped.
- Coatings are almost never right for clay.
- Listed roofs: speak to the council first.
Next step
Send a photo of your clay roof and your postcode. We’ll tell you whether it needs a clean, a treatment only, or nothing yet, and give you a free quote.
