Roof cleaning: what it costs and when it's a bad idea
Roof cleaning is one of the few roofing jobs where the wrong method actively shortens the life of the roof.
Why pressure washing is risky
High pressure strips the protective surface off concrete tiles, drives water under the laps and can shift or crack older slates. Any visible improvement comes at the cost of a faster-weathering roof.
Soft washing and biocide
Scraping the heavy moss off by hand and treating the remainder with a biocide works more slowly but doesn't damage the covering. It is what we recommend on almost every domestic roof.
When cleaning is worth it
Where moss is packed deep enough to dam water behind the tiles, block gutters repeatedly, or fall and clog downpipes. That is a functional problem worth solving.
When it isn't
Light surface moss on a sound roof is cosmetic. If a sales call has told you the roof will fail without immediate cleaning and coating, get a second opinion first.
Roof coatings
We don't recommend sealant coatings on domestic tiled roofs. They can trap moisture in the tile and they complicate any future repair or tile matching.
FAQs
Only when it's genuinely building up. On shaded, north-facing or tree-lined roofs this may be every few years; on open, sunny roofs it may never be necessary.
No. Cleaning can remove a cause — moss damming water — but an existing leak needs the failed detail fixing.
Yes, and it makes sense to, because the debris ends up there anyway.
Related reading
More on costs & budgeting and the jobs that usually come with it.
- Scaffolding: when it is needed and what it addsCosts & budgeting
- Scaffolding for roof work: when you need it and what it costsCosts & budgeting
- Roof repair cost by job: tiles, flashing, chimney, valley, ridge and feltCosts & budgeting
- Landlord roof maintenance: preventing the expensive callProperty types
Looking for something specific? See our roofing services, cost guides, common roof problems or the areas we cover.
Get a fast quote with a costed breakdown
Family-run and Hampton-based. Tell us what you're seeing on the roof and we'll come and look properly before quoting.