Minimum Angle For Slate Roof

Generally speaking 20degrees 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.

Minimum angle for slate roof.

When slating with a shallow pitch a wide slate is highly recommended for maximum side lap or lateral lap side overlaps. Table 1 minimum recommended laps in mm for different exposures and roof pitches moderate exposure index between 3m 2 s and 7m s slate size mm roof pitch length width 85 45 40 35 30 25 221 2 20 600 300 65 65 75 75 90 105 125 500 300 65 65 75 75 90 90 115 500 250 50 65 65 75 75 90 105 120 450 300 50 65 65 75 75 90 100 120. This means for every 12 horizontal units the roof must rise a minimum of 4 vertical units. 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.

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. Also redland cambrian interlocking slate which is very realistic will go down to 15 degrees. 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. 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.

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. Roof pitch refers to the measurement of the slope of a roof and you express this as a ratio. Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more. You consider some alternative solutions.

Although there s isn t any standard pitch of a roof used on all kinds of sloped roofs you can determine the range of pitches by using a roof angle calculator and by considering factors like the local climate and roofing materials. With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 200 for slate roofs. It is agreed that the roof pitch should be a minimum of 20 degrees preferably a bit more.