Minimum Roof Pitch For Natural Slate

The general recommendation for the minimum pitch for natural slate is 25.

Minimum roof pitch for natural slate.

What are the minimum pitches for clay or concrete tiles. Roof pitch 40 roof area m 2 150 length of roof slope m 9 5 the headlap can be found from table 1 by reference to slate size roof pitch and exposure 65 mm. The slate coverage per m2 can be found from table 2 23 9. The total weight of slates on roof can be found from the formula.

Weight of slates kg area of roof m 2 slate. 2003 and bs 6399 part 2 1997 and part 3 1998 based on bs 5534. 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. And our brand new mendip 12 5 can be used at an even lower pitch of 12 5 restrictions on rafter length may apply.

Detailed guidance on wind load calculations is given in bs 5534. The tables above give minimum recommended laps according to exposure roof pitch and slate size. 2003 all headlaps have been rounded up to the nearest 5mm increment moderate exposure less than 56 5 l m2 per spell. The recommendations shown above are based on a maximum height to eave of 12m and a maximum rafter length of 9m in moderate exposure and 6m in severe exposure.

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. There are some manufacturers that can go slightly lower such as the siga 56m natural slate which can go down to 20 in some instances if used with slate hook systems. 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. Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more.