Roof pitch determines which tiles suit your Salisbury roof: clay plain tile needs 35°+, concrete interlocking 17.5–22.5°, Welsh slate 25–30°. Most Victorian properties satisfy clay minimums; post-war estates often cannot. We check pitch at every re-roof survey. Call 0172 223 9611.
Roof pitch — the angle of the slope — is one of the most important factors determining which tiles can be used on your roof. This matters for Salisbury homeowners considering re-roofing or changing tile type.
What Roof Pitch Means
Pitch is measured in degrees. A 45° pitch is steep. A 20° pitch is shallow. Most UK domestic housing sits between 25° and 50°. The pitch determines how quickly water runs off and how much overlap is needed between tiles to remain watertight.
BS 5534 specifies minimum pitches by tile type — clay plain tile requires 35°, meaning it cannot be used on the shallow-pitched post-war estate roofs common across Salisbury's suburbs.
— BS 5534:2014
Minimum Pitch Requirements by Tile Type
| Tile Type | Minimum Pitch | Notes |
|---|---|---|
| Clay plain tile | 35° | High overlap requirement means steep minimum |
| Concrete interlocking | 17.5°–22.5° | Varies by profile — check manufacturer spec |
| Natural Welsh slate | 25°–30° | Depends on gauge and lap |
| Purbeck / stone tile | 45°+ | Heavy stone requires steep pitch |
| GRP flat roof | 1:80 (flat) | Minimum fall to outlet |
Why Pitch Matters for Re-Roofing in Salisbury
If you want to change tile type — from concrete interlocking to clay plain tile, for example — minimum pitch requirements may be an issue. Clay plain tile requires a minimum 35°, which Victorian and Edwardian Salisbury properties typically satisfy (40-50° pitches). Post-war estate housing often has shallower pitches of 22-30°, which precludes clay plain tile. We measure pitch at every re-roofing survey.
How to Measure Your Roof Pitch
A digital angle finder placed against the rafter in the loft gives an accurate reading. From outside, a pitch calculator app using photographs is a reasonable approximation. If you tell us your property era and type, we can usually estimate the likely pitch range from experience and confirm at survey.
Thinking about changing your tile type? We check pitch compatibility as part of every free re-roofing survey across Salisbury and surrounding areas.
📞 0172 223 9611Last reviewed: 21 July 2026 by Salisbury Roofing Experts