Is roof cleaning worth it? When it's money well spent, and when it isn't

Worth it, or not? The short version

When it's money well spent

The roofing industry is clear about when moss needs to go. NFRC, the roofers' trade body, says moss "is rarely a problem and only needs to be removed if it is blocking gutters" and other drainage points. Marley, one of the UK's biggest tile makers, says to leave it unless the roof is leaking or the gutters and outlets are blocked, but warns that a heavy build-up "will inhibit the flow of water off the tiles" and "can potentially cause damage over time if left unchecked".

So the clean is worth it when it solves a real problem. Gutters that block every winter because moss keeps washing into them. A north-facing slope so thick with moss that rain sits on it. Or a survey, like the one a Mumsnet user described, which "advised it needed to be removed".

When you can save your money

Marley says light to moderate moss and lichen is "not harmful to roof tiles or slates" under normal circumstances. It also says "concrete roof tiles rarely require any cleaning or maintenance, other than to ensure debris is removed from the roof".

Looks are a fair reason to want a clean, and that's your call. Just know that a roof changing colour is normal. Marley says tiles "gradually change in appearance over time through the action of natural weathering". A faded roof that keeps the rain out isn't a failing roof.

The real cost of a bad clean

A cheap clean done the wrong way is the most expensive option. On Mumsnet, one homeowner warned to "never jet wash roof tiles as it takes off the surface and makes them brittle". Another described someone who'd "now got a leak on the lower third" after a roof clean. Another found that "the spray and splashes killed all my plants on that side of my garden."

Hertfordshire Trading Standards has warned against the pressure-cleaning and painting sold by doorstep callers, saying experts advise "it is likely to cause damage to the tiles". If a quote involves a pressure washer, it isn't worth it at any price.

What a good roof clean includes

• Moss taken off by hand, with scrapers and brushes, not a pressure washer.
• Work done from roof ladders, not by walking across the tiles.
• A treatment, if it suits the roof, that's approved for use in Great Britain and applied at low pressure, kept off plants and ponds.
• The gutters and downpipes cleared afterwards, because that's where the moss ends up.
• Photos of every slope before and after, so you can see what you paid for.
• An honest word about anything else spotted, such as slipped tiles or worn mortar, without pressure to fix it that day.

One Mumsnet user described a clean done properly: "they hand scraped all the moss off, cleaned the tiles and then treated the roof with a biocide solution".

How long does a clean last?

Moss comes back eventually, and how fast depends on shade, trees and which way the slope faces. A treatment can slow regrowth, but it isn't permanent. Historic England's research found the longer-term effectiveness of common biocides "has been observed to be extremely limited". Going by NFRC's advice, keeping the gutters and outlets clear matters more on most roofs than cleaning the tiles.

Let us tell you if it's worth it

Send us a few photos of your roof from the garden or the street. We'll tell you honestly whether it needs doing now, can wait a year, or doesn't need doing at all. If it does, we take the moss off by hand from roof ladders, treat where it suits, clear the gutters and send you photos of every slope.

Written by Hawkes Roofing, roofers based in St Albans who remove roof moss by hand across Hertfordshire, Buckinghamshire and north-west London. Last reviewed 26 October 2026.