Maximum Pitch For Slate Roof

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.

Maximum pitch for slate roof.

Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or 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. As per the nrca roofing and waterproofing manual fifth edition they recommend that roof deck slopes intended for the application of steep slope materials at 4 12 18 degrees or greater page 405. It is agreed that the roof pitch should be a minimum of 20 degrees preferably a bit more.

Generally a slate roof is not installed on a pitch less than 4 12. Roof tiles and slates are very versatile products and can be used on a variety of roof pitches. You consider some alternative solutions. 11 august 2015 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.

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. Tiles or slates can be used at pitches up to 90 degrees vertical provided a clip is available to securely clip the tail of the tile available for most tiles.