Slate Roof Pitch Regulations

The headlap of the slate is adjusted according to the roof pitch.

Slate roof pitch regulations.

Conventional low pitch slate roofs are recommended down to a minimum of 20 in areas of sheltered or moderate exposure providing a 500x300mm slate is used and a headlap of 115mm. Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater. Traditionally a minimum roof pitch of 20 was recommended in bs 5534 but modern tiles and slates have now been designed for applications as low as 15. It is uncommon to find a roof below 15 but for those very low pitch applications there are interlocking clay pantiles available suitable for use down to 12 5.

This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units. In order to provide you with the opportunity to specify low pitched slate roofs below 20 with confidence siga commissioned the bre to carry out a set of tests. Minimum roof slope roof pitch r905 3 2. Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more.

You consider some alternative solutions. The roof pitch should be at least 20 which is influenced by the length head lap and thickness of the slate. Where the thickness of natural slates reduces their pitch by 3 or more select the next lower rafter pitch to determine the recommended head lap and slate width. Minimum fixing on double lap slates.