Moss and lichen treatment, biocide application and roof cleaning across Portsmouth and the Hampshire coast. Portsmouth's coastal humidity means moss grows faster and causes damage sooner than in inland towns — leaving it untreated accelerates mortar failure, cracked tiles and blocked valleys. We use soft-wash biocide treatment, not high-pressure washing that damages older tile surfaces.
Roof cleaning in Portsmouth uses soft-wash biocide, never pressure washing which damages tiles. Treatment lasts 2 to 4 years and costs £200 to £750 by roof size. We check nail sickness on post-war estates at the same time. Free assessment — call 0239 307 1334.
Portsmouth is one of the highest moss-load environments for roofing in south Hampshire. Coastal humidity, significant annual rainfall, salt-laden air that encourages biofilm growth on tile surfaces, and the prevalence of north-facing slopes in the back-to-back terrace format of Fratton, North End and Southsea create conditions where moss and lichen establish and spread faster than in drier inland towns.
Left untreated, moss does structural work over time. It retains moisture against mortar pointing, accelerating freeze-thaw cycling that cracks bedding mortar on ridge and valley tiles. In valley gutters, moss acts as a dam, backing water up under tile courses and causing leaks that are difficult to trace. The correct treatment — soft-wash biocide application — kills the moss at the root, after which it dies and weathers off over 3 to 6 months without the tile surface damage caused by pressure washing.
Moss on your Portsmouth roof? We assess the load, identify any underlying repair issues, and quote treatment in writing.
0239 307 1334Mon–Fri 8am–6pm · Sat 8am–2pm · 24/7 Emergency
"North-facing rear slope on our Fratton Victorian was completely green. Portsmouth Roofing did the biocide treatment and cleared the valley at the same visit. Four months later the moss has completely gone. Also spotted a ridge tile issue while up there."
"Had a company quote for pressure washing our Cosham semi. Portsmouth Roofing specifically advised against it given the age of the concrete tiles — said it would do more harm than good. Did the soft-wash biocide instead. Tiles are clean and still intact."
"Paulsgrove semi with heavy moss on both rear slopes. Treatment done in two hours, gutters cleared at the same visit, written report with photos provided."
Biocide moss treatment on a standard 3-bed semi in Portsmouth typically costs £200 to £450 depending on roof area and moss coverage. Full written quotes before we start.
We do not recommend high-pressure washing on older clay tiles, Welsh slate or concrete tiles with surface erosion — the water pressure removes the protective surface and accelerates decay. We use low-pressure soft washing and biocide treatment as standard.
Yes, over time. Moss retains moisture against mortar joints and tile surfaces, accelerating freeze-thaw cracking. Portsmouth's higher ambient humidity means moss growth is more aggressive than inland Hampshire and the structural consequences arrive sooner.
Biocide treatment typically lasts 3 to 5 years in Portsmouth's coastal conditions. Properties with north-facing slopes, heavy tree canopy or harbour-adjacent positions will need attention at the shorter end of that range.
Yes — we always include a gutter check and clear as part of a roof cleaning visit. Moss that has been treated sloughs off over 3 to 6 months and some will wash into gutters.
Yes free no-obligation written quotes on all work. No call-out fee. Call 0239 307 1334.
Yes. NFRC registered, fully insured, 10-year written guarantee on all work.
No call-out fees. No obligation. Just an honest quote from a local Portsmouth roofer.
0239 307 1334