How long does roof cleaning last?
Nobody can put an honest number on it that applies to every roof. Growth returns at the speed the roof's position allows, and that varies enormously between two houses on the same street.
A south-facing pitch that dries quickly after rain stays clean far longer than a north-facing slope under overhanging trees.
What speeds regrowth up
- Shade from trees, neighbouring buildings or a steep adjacent pitch
- Overhanging branches dropping debris and keeping the tiles damp
- A porous or previously pressure-damaged tile surface
- Blocked gutters keeping the lowest courses permanently wet
- Sheltered, still positions where the roof dries slowly
What slows it down
Keeping gutters and downpipes clear, cutting back anything overhanging the roof, and not damaging the tile surface during cleaning all make a real difference.
Nothing available makes a roof permanently moss-proof, and any claim otherwise is worth treating carefully.
Judging when it needs doing again
Check the gutters rather than the tiles. When moss debris starts appearing in the gutter runs again, growth on the roof has re-established enough to be worth dealing with.
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.