Slate Roof Pitch Regulations

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.

Slate roof pitch regulations.

It is agreed that the roof pitch should be a minimum of 20 degrees preferably a bit more. A couple of likely slate suppliers are consulted and they confirm that they are happy to supply 600x300mm slates for a minimum roof pitch of 20 degrees assuming a minimum lap of 125mm. This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units. 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. The roof pitch should be at least 20 which is influenced by the length head lap and thickness of the slate. Minimum roof slope roof pitch r905 3 2. You consider some alternative solutions.

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. Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more. The headlap of the slate is adjusted according to the roof pitch.