Case Study: Period Slate Roof Clean, Hampshire

Property:
Period detached, natural slate roof

Condition:
Uniform biological staining, light moss in valleys and ridge junctions

Scope:
Sympathetic soft-wash treatment tailored to natural slate

Duration:
Full day, careful pace

Typical price:
£900 – £1,400 typical for a slate property this size

Guarantee:
5-year biocide guarantee (partner-issued)

The Property

A Hampshire period detached property with a natural slate roof — the kind of substrate that punishes any contractor who tries to shortcut a job. Slate is far more sensitive than concrete or clay, and any use of high-pressure water on it strips the natural surface and shortens the life of the tiles.

The Condition

Uniform biological darkening across all slopes — typical for a slate roof that hadn’t been cleaned in 8+ years. Light moss build-up in the valleys and around ridge junctions where moisture pools. Otherwise structurally sound, with all slate slips intact.

Why Slate Needs a Different Approach

Slate cannot be pressure-washed. Full stop. What works on a modern concrete tile roof will destroy natural slate in a single afternoon. Our approach on this job:

Soft-brush moss removal by hand in the valleys and at ridge junctions, avoiding any lifting force on the slate itself
Diluted biocide application via low-pressure soft-wash — slower to work than on concrete, but sympathetic to the substrate
No pressure washing whatsoever — not at any pressure, not at any point
Extended dwell time to allow the biocide to work through the biological film without needing mechanical scrubbing

The Result

Slate returned to its natural darker-grey tone. Because the biocide keeps working for weeks after the visit, the final “cleaner still” finish emerges over the following month rather than on the day itself — this is normal and expected on slate.

Timeline

Full day on site — slower pace than a concrete tile job because of the substrate sensitivity. No follow-up needed. 5-year biocide guarantee applies.

Typical Cost

Period slate properties of this size typically fall in the £900–£1,400 range. Slate is more sensitive and slower work — the cost reflects the extra care needed, not any material difference in what’s applied. Your exact quote is confirmed by the matched partner after photos.

Photos

Photos from our partner network. Each caption tells you exactly what you’re looking at — whether it’s this property, or a matched-tile close-up, or a method illustration from a comparable job. We don’t pretend two different houses are the same house.