Maximum Pitch For Slate Roof

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.

Maximum pitch for slate roof.

Generally a slate roof is not installed on a pitch less than 4 12. 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. You consider some alternative solutions. What is the maximum roof pitch for a roof tile.

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. 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. Roof tiles and slates are very versatile products and can be used on a variety of roof pitches. It is agreed that the roof pitch should be a minimum of 20 degrees preferably a bit more.

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.