Moss is everywhere on Surrey roofs, and it thrives in the shade of mature trees in places like Esher, Cobham, Oxshott, Weybridge and Woking. A little moss is mostly a cosmetic issue, but heavy growth can block gutters, hold water against your tiles and, in the worst cases, lift them. Here's what you need to know about when moss matters and how to remove it without damaging your roof.
Is Moss Actually a Problem?
A light dusting of moss isn't an emergency. It becomes a problem when:
- It's thick enough to lift tiles: moss growing in the gaps between tiles can push them up, letting rain blow underneath.
- It's blocking gutters and downpipes: clumps washed off in heavy rain clog gutters and cause overflows, often leading to damp walls.
- It's holding moisture: moss acts like a sponge, keeping tiles wet for longer. In winter, that water can freeze and damage porous tiles.
- It's in valleys: moss in the valleys where two roof slopes meet slows water down and can cause it to back up under the tiles.
Why You Shouldn't Pressure Wash Your Roof
Pressure washing looks quick and satisfying, but we strongly advise against it on most roofs. High-pressure water can:
- Strip the protective surface from concrete and clay tiles, making them more porous and encouraging moss to grow back faster
- Force water up and under tiles, soaking the felt and battens beneath
- Dislodge or crack tiles, slates and ridge mortar
It's also dangerous: standing on a wet, mossy roof with a pressure washer is a recipe for a serious fall.
How Moss Should Be Removed
A safe, professional moss removal usually involves three stages:
- Manual removal: the bulk of the moss is gently scraped off by hand, working down the slope so tiles aren't lifted.
- Biocide treatment: a specialist treatment is applied at low pressure to kill remaining spores and slow regrowth. It keeps working for months after it's applied.
- Gutter clear-out: gutters, downpipes and valleys are cleared of all the debris, so the job doesn't just move the problem lower down.
While we're up there, we also check for slipped tiles, loose ridges and tired flashing, so any small repairs can be done at the same time.
Can I Do It Myself?
We don't recommend going on the roof yourself. Moss makes tiles extremely slippery, and most falls happen on what seemed like a quick job. What you can do safely from the ground is keep an eye on the roof with binoculars, clear accessible gutters from a properly secured ladder, and cut back overhanging branches (or ask a tree surgeon to).
How Often Should Moss Be Treated?
It depends on your roof's exposure. A sunny, open roof might only need attention every five years or more. A north-facing roof under trees might need treating every two to three years. Autumn and early spring are good times, ahead of the wettest months.
Moss on Flat Roofs
Flat roofs on extensions and garages can collect moss and debris in areas where water ponds. Clearing it helps the roof drain, but it's also worth checking why water is collecting: poor falls are often a sign the roof needs attention. Our flat roofing page explains the options.
Book a Moss Removal or Roof Check
We remove moss safely, treat the roof and clear the gutters across West Molesey, Elmbridge and Surrey. See our gutters and fascias and roof repairs services, and our winter maintenance checklist. Call 07470 744247 for a free quote.