Slate Roof Pitch

Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more.

Slate roof pitch.

Generally speaking 20 degrees is the lowest advisable pitch for a slate roof depending on the size of the slates and how much that the roof is exposed to moderate weather conditions. At that point measure down from the exposed butt end back to the roof surface. Generally a slate roof is not installed on a pitch less than 4 12. Place the butt end of the level against the edge of the roof and extend it into the air balancing it until it becomes level.

But since there is still a wide variety of slate roofing systems there are occasions when the minimum pitch can go down to as low as 15 0 depending on the uniqueness of the roof. For example if the level is 4 above the roof at a point 12 away from where the level is touching the surface then the pitch is 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. When slating with a shallow pitch a wide slate is highly recommended for maximum side lap or lateral lap side overlaps.

With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 200 for slate roofs. They have a pitch ranging from 4 12 to 9 12. You consider some alternative solutions. Page 405 roof slope.

Although bs 5534 recommends a minimum pitch of 20 ssq has developed a successful slate roofing system that allows the roof s pitch to be reduced to 17 5 generally and under some circumstances as low as 15 in areas considered to be unexposed. 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. 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. 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.

Conventional roofs are the easiest to construct and you can walk on them safely. High pitched roofs often need extra fasteners and their pitch can be as high as 21 12. You can also calculate roof pitch even without using a roof slope calculator. These roofs have a pitch less than 4 12.

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 slope of a roof is often referred to as the roof s pitch. Minimum roof pitch for shingles. The tools required will be a contractor s level at least 24 inches long and a tape measure.