Slate Roof Pitch Minimum

Minimum pitch for slate roof when considering the minimum pitch for a slated roof it is necessary to establish the exposure of the site the length of rafter and the height of the building.

Slate roof pitch minimum.

It is agreed that the roof pitch should be a minimum of 20 degrees preferably a bit more. But since there is still a wide variety of slate roofing systems there are occasions when the minimum pitch can go down to as low as 15 0 depending on the uniqueness of the roof. 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. 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.

You consider some alternative solutions. 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. The recommendations shown above are based on a maximum height to eave of 12m and a maximum rafter length of 9m in moderate exposure and 6m in severe exposure. Our suggestion is not to contemplate using slates on roofs with a pitch less than 20 degrees and then only for big format slates eg 500x300mm.

With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 20 0 for slate roofs.