The function of a roof is to protect the building below from the weather.
Minimum roof pitch uk building regs.
In order to satisfactorily fulfil this function over a period of years it must be strong stable and durable.
Choosing the right pitch.
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.
35 is considered to be the minimum for slate and clay but if you do need to go below this interlocking concrete tiles are the best option.
Deciding on the correct roof pitch for your home very much depends on the style of house you are building or renovating and to a lesser extent your local area.
To enable compliance with the requirements of the building regulations to be demonstrated full details of the new roof will be needed including.
Mineral surfaced roll roofing requires a minimum roof pitch of 1 12 or greater.
Built up roofs require a minimum roof pitch of 1 4 12 or greater.
In addition roofs must provide good thermal insulation and prevent the spread of fire from adjacent or adjoining properties.
A thermal layer of fibreglass polystyrene or other insulating material should be inserted either above the roof decking the warm roof model which is suitable for homes or permanent residences.
Flat roof drainage.
Or else on the interior of the building just.
Wood shakes require a minimum roof pitch of 3 12 or greater.
Wood shingles require a minimum roof pitch of 3 12 or greater.
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.
It also requires that roof coverings are fixed correctly.
Flat roof this usually consists of felting which has a slight fall to allow rain water to drain off.
Pitch roof this is where tiles or slates are used and a void is usually created underneath.
This will inevitably result in fixing calculations being required and complied with for all roofing projects covered by building regulations.
Thermoplastic or elastomeric are the most effective and should extend up adjacent walls at least 150mm from the roof surface.
A correctly build flat roof will drain the rainwater quickly and effectively into the gutters without allowing water to collect in depressions and pond on the surface of the roof leading to the build up of silt deposits on the roof and stresses in the membrane when the water freezes a small amount of ponding is inevitable and it should not reduce the.
In accordance with the guidance in bs 8000 part 6 which in turn direct users to the wind uplift calculations in bs 5534.
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.
Slate and slate type shingles require a minimum roof pitch of 4 12 or greater.
