Slate Roof Pitch Minimum

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.

Slate roof pitch minimum.

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. Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more. 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. You consider some alternative solutions.

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. 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. With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 20 0 for slate roofs. It is agreed that the roof pitch should be a minimum of 20 degrees preferably a bit more.

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.