What Roof Pitch Do I Need?
Quick Answer
30° is the most common UK domestic roof pitch
Minimum 15° for interlocking concrete tiles, 35° for plain tiles, 12.5° for slates
How to Calculate Roof Pitch
Pitch is the angle of the roof slope, measured in degrees from horizontal:
- Pitch (degrees) = arctan(rise ÷ run)
- Rise: vertical height from wall plate to ridge
- Run: horizontal distance from wall plate to centre of building (half span)
Example: 2.5m rise over 4.33m run = arctan(2.5/4.33) = 30°
Minimum Pitches by Covering
- Plain clay/concrete tiles: 35° minimum
- Interlocking concrete tiles: 15°–22.5° (check manufacturer)
- Natural slates: 20°–25° (depending on size)
- Fibre-cement slates: 20°
- Profiled metal sheeting: 5°–7°
- Flat roofing (felt/membrane): Minimum fall of 1:40 (1.4°)
Common UK Pitches
- 22.5°: Low-pitch modern builds, interlocking tiles
- 30°: Standard UK domestic pitch
- 35°–40°: Traditional/Victorian, plain tiles
- 45°+: Steep period properties, some Scottish vernacular
Why Does Pitch Matter?
Steeper pitches shed water and snow faster but use more materials. Shallower pitches reduce material cost but require more weatherproofing (e.g., underlay type, headlap). The pitch also determines headroom for loft conversions — a minimum of 2.3m standing height is needed.
Last updated: April 2026. Always check the tile or slate manufacturer’s minimum pitch recommendation and local exposure conditions.