The pitch of a roof is determined by 2 numbers.
Slate tile roof pitch.
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.
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.
The rise and the length.
Most commonly a roof pitch will be from 0 flat to 12 45.
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.
In areas with high winds the underlayment must be attached with corrosion resistant fasteners according to manufacturer s instructions.
Roof pitch is a term used in the roofing industry to describe the angle slope of a roofing structure.
Additionally if the climate can cause backups of water as ice under the eaves the tile requires at least two layers of underlayment cemented together.
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.
For tile shingle slate and metal roofing.
When slating with a shallow pitch a wide slate is highly recommended for maximum side lap or lateral lap side overlaps.