There's a right way and a wrong way to get moss off a roof, and the wrong way tends to do more damage than the moss itself ever would. Getting this right protects both the tiles and whoever's doing the work.
Why gentle methods beat brute force
Scrubbing hard with a stiff brush or blasting tiles with a high-pressure jet washer might look effective at first, but it strips the protective granule coating off concrete tiles and can crack older or more brittle slate outright. The safer approach is a soft wash, low-pressure water combined with a biocide treatment that kills moss at the root, followed by gentle hand removal of the loosened growth rather than aggressive scraping.
This method takes moss off without chewing up the tile surface underneath, and it also tends to slow down how quickly moss comes back compared with a quick scrub that leaves spores and roots behind.
Why this isn't really a DIY weekend job
Working at height on a wet, sloped roof is genuinely dangerous, and every year people are injured doing exactly this kind of job from a ladder without proper safety gear. There's also the practical issue that untrained hands often can't tell which tiles are sound and which are already compromised, so damage can go unnoticed until a leak shows up months later.
Brunel Roofing Bristol is fully insured and uses proper access equipment and safe, tile-appropriate methods, so the job gets done without putting the roof, or anyone on it, at risk.
What a professional clean typically involves
A typical visit starts with an inspection of the tiles and gutters, followed by application of a biocide treatment that's left to work into the moss and lichen rather than being rinsed straight off. Once the growth has loosened, it's cleared by hand or with soft brushes and low-pressure water, and any debris washed down during the process is cleared from the gutters at the same time so it doesn't cause a blockage later.
Good practice also includes a check of the tiles themselves once they're visible again, since cleaning often reveals cracked, slipped or worn tiles that were previously hidden under moss growth. Flagging these at the same visit means they can be dealt with before the next spell of heavy rain finds a way through.
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