While house building is governed by stringent regulations in the UK, these do not extend to the pitch of a shed roof. There is no single recommended pitch for a shed roof, so the slant you choose for your shed depends on several factors, including the size of the shed, weather conditions and local council planning guidelines.
The pitch of a shed roof may be determined by the shed’s other dimensions and its placement within the footprint of the property. According to the Department for Communities and Local Government, there are maximum heights for buildings within the area surrounding the house without planning permission. These maximum heights also apply to sheds. The maximum height of a building with a dual pitched roof is 4 metres. A dual pitched roof is one with a ridge and two surfaces. If the shed is 2 metres or less away from the boundary, the height limit is 2.5 metres. In other cases, such as a single pitched roof, the height limit is 3 metres. Maximum height to the eaves is 2.5 metres.
A pitch of 10 degrees or less is typically regarded as a flat roof. The reason for a pitched roof is to cause rain to run off the roof surface. A flat roof is more likely to allow rain to pool and this can cause damage, especially if the roof is made of a porous substance like wood. In the case of a shed roof, a layer of roofing felt usually offsets the porosity of the wood. Use a pitch of more than ten degrees for more efficient rain protection.
If the shed is part-built to wall height, you can determine the necessary pitch by deciding upon the required headroom. Stand in the shed holding a long piece of wood vertically beside you. Mark a line on the wood above your head leaving a comfortable headroom space. Measure the piece of wood to the line. You now know the maximum height of the roof. The roof needs to slope from the top of the walls to this point.
Using a clinometer
A clinometer is a simple device for measuring the angle between two points, or the pitch of a slope. In its simplest form, it is an upside-down protractor with a weighted string dangling from the centre point. As the line of sight inclines more, the clinometer registers a larger angle. While you hold the wood, get a friend to use a clinometer to tell you the angle between the top of the shed walls and the marked line. This will give you the required roof pitch.