Most modern roofs are constructed with trussed rafters. These are slightly cheaper than traditional cut roofs, but their main advantage is that they can be erected on site with relatively unskilled labour. Conversely constructing a traditional cut roof can be a highly skilled job. Their main disadvantage is that in the majority of cases the roofspace is full of bracing timbers and cannot be used for anything.

Sometimes customers want an open roofspace constructed in a traditional way. Often this is because they have future plans to use the roof space.

The main issue with this type of roof is that, unlike with trussed rafter roofs, internal supporting walls will be required if the length of the ridge is much more than around 6m. These walls should be at right angles to the ridge and they should be positioned beneath the purlins. This is not normally a problem, but is does need to be incorporated into the design of the building.

Our ridged roof design includes carrying out a detailed structural analysis of the rafters, purlins and ceiling joists. Our structural design also includes specifying the necessary timber sizes and any connection details.

We need the following information to design a traditional ridged roof:

architectural layouts and elevations or sketch drawings with dimensions showing the overall layout of the building and the position of any internal loadbearing walls

the height(s) of the roof

the type of roof covering

the approximate location of the building

Design information

All design work is carried out in accordance with BS5268 (The structural use of timber).

The calculations provided will be suitable for Building Regulation approval.