Soft-wash biocide moss treatment across Portsmouth. No pressure washing — ever. We assess moss growth, specify the correct biocide for your tile type, and advise on treatment intervals for coastal conditions.
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📞 Call Now: 0239 307 1334Roof moss removal in Portsmouth uses soft-wash biocide from £200, never pressure washing. Coastal humidity drives fast regrowth, so treatment is calibrated to your roof aspect and combined with a nail-sickness check on estate properties. Free survey — call 0239 307 1334.
Portsmouth's coastal location creates a persistently damp microclimate across Portsea Island and the surrounding area. North and east-facing roof slopes receive morning salt-laden humidity from the harbour with limited afternoon sun to dry them — ideal conditions for moss and lichen establishment. Post-war concrete interlocking tiles on Paulsgrove, Leigh Park and Bridgemary estates are the worst-affected stock: the surface aggregate on these tiles has been eroding for decades, and the increasingly porous surface holds moisture against the tile face for longer after rain. South and west-facing slopes with direct Solent UV exposure are less prone to moss but more prone to algae and lichen, which bleach to a grey-white discolouration.
Pressure washing is routinely offered by general cleaning companies for roof moss removal. We do not use it and advise strongly against it. High-pressure water drives water under tile laps where it cannot drain, removes surface aggregate from concrete tiles accelerating porosity, and forces water into any existing crack or degraded pointing. On nail-sick post-war estate roofs it can displace already marginal tiles. The result is visible tile damage and accelerated deterioration on properties that were already at risk.
Soft-wash biocide treatment applies a specialist biocide at low pressure. The biocide kills moss, algae and lichen at root level without any mechanical impact on tiles. The dead material then disperses naturally in rainfall over several weeks. Residual biocide provides 2 to 4 years of protection against re-establishment depending on aspect and exposure.
We assess moss coverage and advise on the correct treatment interval for your aspect and exposure. Free survey — call 0239 307 1334.
Call 0239 307 1334Established moss on Portsmouth post-war estate concrete tile roofs reaches a weight and water-retention level that affects tile seating and increases roof load within 5 to 10 years of first establishment. Dense moss growth on a standard concrete interlocking tile slope can add 15 to 30 kilograms per square metre to the roof when fully saturated — a meaningful additional load on roof timbers that were not designed for it. More critically, on nail-sick roofs the additional weight and the daily expansion and contraction of the moss root system actively accelerates nail fatigue. We combine moss treatment with a nail sickness assessment on post-war estate properties as standard practice.
South and west-facing slopes with direct Solent exposure: treatment typically needed every 4 to 5 years. North and east-facing slopes in sheltered positions: every 3 years in most Portsmouth locations. Properties with heavy adjacent tree canopy — common in Southsea, Cosham and Waterlooville — may need treatment every 2 to 3 years regardless of aspect. We advise on the correct interval at the time of treatment based on actual growth levels observed during the survey.
| Service | Cost Guide | Notes |
|---|---|---|
| 2-bed terrace (soft-wash treatment) | £200–£350 | Full roof + gutter clear included |
| 3-bed semi (soft-wash treatment) | £300–£500 | Full roof + gutter clear included |
| 4-bed detached (soft-wash treatment) | £450–£750 | Full roof and gutters |
| Combined treatment + nail sickness survey | POA | Recommended on estate properties |
| Lichen removal (specialised biocide) | £350–£600 | Longer kill cycle than moss |
"Paulsgrove estate semi — heavy moss across the rear slope. Portsmouth Roofing assessed the nail sickness at the same time. Treatment done, nails re-fixed where needed. One visit sorted both issues."
"North-facing Victorian terrace in Fratton — moss had been building for years. Soft-wash treatment, no damage to the original tiles. Cleared progressively over about 6 weeks as advised."
"Southsea loft extension flat roof — algae and lichen on the GRP surface. Portsmouth Roofing used the correct biocide for GRP rather than the standard tile formula. Spotless now."
Moss and algae show as green or black growth across the tiles, especially on north-facing slopes, and as clumps of moss dropping into the gutters.
When it is not the answer: Pressure washing a tiled roof is never the answer — it drives water under tiles and strips the surface; soft-wash biocide is the only safe method Read the full guide.
Solent salt air and exposed Channel weather corrode fixings and lift tiles faster than inland Hampshire. Portsea Island's dense Victorian terraces mean rear elevations are often reached only through tight alleys, and front scaffold needs permit-controlled pavement space. It is why we specify marine-grade fixings and correct lead codes as standard on Portsmouth roofs — the coastal environment punishes anything less.
We assess the growth, roof aspect and tile condition, and check for nail sickness on estate stock at the same time.
An itemised quote for soft-wash biocide treatment — never pressure washing.
We book the treatment and arrange safe access.
We scrape heavy growth by hand and apply a biocide that kills moss and algae at root level over several weeks.
Gutters cleared of fallen debris and your work documented.
| Job | Typical duration |
|---|---|
| Soft-wash treatment (semi) | Half a day |
| Full clean and scrape (detached) | 1 day |
| Gutter clear add-on | 1–2 hours |
| Biocide root-kill period | Several weeks to fully work |
Biocide needs a dry spell to work into the growth — we apply it ahead of settled weather where possible.
Roof cleaning works from towers or ladders with roof ladders for the slope; scaffold only on complex roofs. Scaffold is specified for: steep or high roofs where safe standing time is needed - always itemised in your written quote, never a hidden extra, and we arrange it.
Portsea Island's dense Victorian terraces mean rear elevations are often reached only through tight alleys, and front scaffold needs permit-controlled pavement space. Pavement scaffold and skip permits go through Portsmouth City Council; allow a few working days on streets like Albert Road, Fawcett Road, Marmion Road where space is tight.
| Job | Typical range | Notes |
|---|---|---|
| Slipped or cracked tiles | £150–£350 | Per visit incl. access |
| Leak diagnosis & repair | £150–£500 | Depends on water travel |
| Chimney flashing | £200–£600 | Code 5–6 lead |
| Valley repair | £400–£900 | Strip and re-lay |
| Nail-sickness re-fix (per slope) | £600–£1,200 | Estate stock |
Worked example: A typical job on a property off Albert Road in Portsmouth, including access and waste removal, sits in the middle of the ranges above once surveyed.
No deposit on repairs under £500. Staged payments on re-roofs — nothing up front before materials are on site. All prices include VAT; written itemised quote before any work.
Covering PO1, PO2, PO3, PO4, PO5, PO6 and surrounding postcodes.
Our workmanship is guaranteed; the biocide continues working for weeks and slows regrowth for two to four years by aspect.
If a fault appears in covered work, we come back and put it right. No quibbling, no re-charge.
External-only work, no internal disruption — we protect planting below and clear fallen moss from gutters and paths. You do not need to stay home for external work - we just need power and access agreed in advance.
We soft-wash in dry conditions so the biocide isn't immediately rinsed off; coastal humidity means regrowth is slower after a proper root-kill. Solent salt air and exposed Channel weather corrode fixings and lift tiles faster than inland Hampshire.
From £200 for a 2-bed terrace to £750 for a 4-bed detached. Includes full soft-wash biocide treatment and gutter clearing. Free written quote — call 0239 307 1334.
No — pressure washing damages tile surfaces and forces water under laps. We use soft-wash low-pressure biocide only. Pressure washing should not be used on any Portsmouth roof.
2 to 4 years depending on aspect and exposure. North and east-facing slopes in coastal humidity need treatment more frequently than south-facing positions.
Yes on post-war estate properties — established moss weight accelerates nail fatigue on already-corroded fixings. We include a nail sickness assessment on all estate property moss treatment jobs.
No — our soft-wash biocide is safe on clay tiles, Welsh slate, concrete interlocking and GRP flat roofs. We check for any zinc-coated elements before treating.
Moss dies progressively over 4 to 8 weeks after biocide application. Dead material disperses in rainfall over subsequent months. Return inspection at 6 months confirms clearance.
Yes — lichen requires a specialised biocide and a longer kill cycle than standard moss. We identify lichen separately during the survey and specify the correct treatment. Call 0239 307 1334.
No call-out fees. No obligation. Local Portsmouth roofers.
0239 307 1334