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.
Minimum pitch for slate roof ireland.
The roof finish manufacturer will specify the minimum and maximum pitch required to ensure weatherproofing.
The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code.
Minimum pitch for slate roof when considering the minimum pitch for a slated roof it is necessary to establish the exposure of the site the length of rafter and the height of the building.
In general terms the minimum pitch is 22 5 degrees but we have seen pitched roofs perform down to 15 degrees pitch.
2002 irish code of practice for slating and tiling.
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.
The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.
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.
In the past slates were thought to be effective at 22 5 degrees and this was set as the minimum acceptable pitch.
Relating to the pitch the building standard code bs 5534 recommends a minimum pitch of 20 deg for slate roofs which can be achieved through specific design although most manufacturers recommend a 25 degree minimum pitch.
Higher exposure or different sized slates necessitated a greater roof pitch of 22 5 or more.
A greater pitch is likely to make the house look top heavy.
The answer depends on a number of factors such as height rafter length site location slate or tile being used etc.
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.
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.
The min pitch for slating was changed from 22 5 to 25 in 2002.