Can roof tiles be pressure washed?
There is no single answer, and anyone giving you one without looking at the roof is guessing. Some robust, sound concrete coverings tolerate controlled washing. Many roofs do not.
The risks are the same everywhere: eroding the face of the tile, forcing water up under the laps, and dislodging tiles that were already loose.
What decides suitability
- The covering — concrete, clay, slate, or a coated profile
- Age, and whether the surface is already porous or flaking
- Existing damage: cracked, slipped or previously repaired tiles
- How the roof is constructed, including underlay condition and laps
- Access, pitch and whether the roof can safely be worked on at all
What high pressure does to a tile
Concrete tiles have a denser outer face. Strip it and the tile underneath is more absorbent, so it holds water and greens up faster than before. That is not reversible.
Water driven upwards under the laps has nowhere sensible to go, and on an older roof with tired underlay it can end up inside the loft rather than in the gutter.
What is used instead
Where a roof is suitable for cleaning at all, the usual approach is careful removal of the bulk of the growth followed by a low-pressure treatment, then clearing the gutters and downpipes of everything that has come down.
Where a roof is too fragile, the right advice is to leave it or get a roofer to look first. A clean that shortens the life of a roof is not a saving.
Want it looked at properly?
Send a few photographs of the elevation along with the address, and Rob will tell you what can realistically be improved, what it will cost and when it can be done.