Roof cleaning and moss treatment in Cosham using soft-wash biocide — never damaging pressure washing. Cosham's mature tree canopy on the 1930s semi streets creates heavily shaded north-facing slopes where moss establishes rapidly.
Portsmouth coastal humidity creates a persistently damp microclimate on north and east-facing slopes. Cosham properties see faster moss establishment and need more frequent treatment cycles than equivalent inland properties.
Low-pressure biocide application to all tile surfaces. Treatment of ridge, hip and valley lines. Gutter clearing included. We never use pressure washing which damages tile surfaces and forces water under laps.
On post-war estate properties in Cosham with concrete interlocking tiles, established moss adds weight to already nail-sick fixings. We combine biocide treatment with nail sickness assessment on estate properties.
Cosham's mature tree canopy on the 1930s semi streets creates heavily shaded north-facing slopes where moss establishes rapidly. The Drayton Road and Medina Road corridors with mature avenue planting need the most frequent treatment. We carry out soft-wash biocide application — never high-pressure washing, which damages tile surfaces and forces water under laps. The biocide kills existing moss and lichen at root level and provides residual protection of 2–4 years depending on exposure.
Low-pressure biocide application to all tile surfaces. Treatment of ridge, hip and valley lines where moss establishes fastest. Gutter clearing included to remove debris loosened during treatment. Return inspection at 6 months — moss dies progressively over weeks after treatment, not immediately.
Untreated moss growth in Cosham's humid coastal conditions eventually reaches a weight and water-retention level that affects tile seating and increases roof load. Beyond a certain point, moss removal should be combined with a nail sickness assessment — the weight and movement of established moss accelerates nail fatigue on already-marginal fixings.
| Service | Cost Guide | Notes |
|---|---|---|
| Biocide soft-wash treatment (2-bed) | £200–£350 | Including gutter clear |
| Biocide soft-wash treatment (3-bed semi) | £300–£500 | Including gutter clear |
| Biocide treatment (4-bed detached) | £450–£750 | Full roof and gutters |
| Combined treatment + nail sickness survey | POA | Recommended for older stock |
"1930s semi on Drayton Lane — re-roof the second time for this property. Portsmouth Roofing was honest that the tiles were past repair and specified the right modern equivalent. No pressure, good advice."
"Nail sickness on our post-war Cosham property. Both main slopes assessed and re-fixed with stainless. Explained exactly what nail sickness means and what to watch for."
"Flat roof on our 1970s rear extension — GRP in a day. They matched the upstand height to the existing brickwork exactly. Neat finish."
Yes — Cosham is within our core service area. Call 0239 307 1334 for availability and free quote.
Yes — free, no-obligation survey and written quote before any work starts. No call-out fee.
Yes. NFRC registration, full public liability insurance and 10-year written guarantee on all work.
Most jobs are surveyed within 48 hours and started within 1–2 weeks. Emergency work is available same day — call 0239 307 1334.
No — pressure washing damages tile surfaces and forces water under laps. We use soft-wash low-pressure biocide application only.
Every 3–5 years depending on exposure and aspect. Cosham's coastal humidity means moss re-establishes faster than inland — south and west facing roofs may need treatment every 3 years.
No — our soft-wash biocide is safe on all tile types including clay, concrete interlocking and Welsh slate.
No call-out fees. No obligation. Local Portsmouth roofers covering this area.
0239 307 1334