Slate Roof Pitch Regulations

The roof pitch should be at least 20 which is influenced by the length head lap and thickness of the slate.

Slate roof pitch regulations.

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. Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater. 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. Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more.

It is agreed that the roof pitch should be a minimum of 20 degrees preferably a bit more. This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units. You consider some alternative solutions. The headlap of the slate is adjusted according to the roof pitch.

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. Headlap as defined in the national slate association s slate roofs design and installation manual 2010 edition is the length in inches of the upper portion of a roofing slate that is covered by the butt of the slate two course above. Minimum fixing on double lap slates. 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.