Principles of pitched roof construction
There are a number of ways to design and construct pitched roofs using timber. Traditionally, builders constructed them on site, cutting and fitting each piece to its neighbours. Following the Second World War, various forms of prefabricated truss were developed, with the intermediate rafters and purlins cut and fitted on site.
Currently, the highly engineered and slender trussed rafter, where the rafters and ceiling joists are triangulated to form a lightweight prefabricated truss, is the most widely used form of domestic roof construction.
This Wood Information Sheet (WIS) covers the general principles of pitched roof design only. It does not cover the design of hatches, chimney openings or the additional support that is required for water tanks or other added loads.
- Site-constructed roofs
- Purlin roofs
- Bolted and connectored trusses
- Trussed rafter roofs
- Rooms in the roof
- Insulation and ventilation
- Preservative treatments
Widely used for a range of building types, trussed rafters are an economical, versatile and straightforward solution to providing a roof over a building.
Trussed rafters are individually designed prefabricated structural components made from strength-graded timber members of the same thickness, joined together with punched metal plate connectors....
Trussed Rafters have become part of the modern building vocabulary. Around 95% of all new house roofs are constructed using trussed rafters as are an increasing proportion of roofs for nondomestic premises such as offices, retail outlets, hospital extensions, leisure developments etc.
This product Data Sheet has been produced...
Roofing battens are fundamental to a roof structure and are used in a loadbearing capacity. They are designed to carry the load of slated and tiles roofs as well as imposed loads caused by wind and snow. In addition, they may be required to provide a reasonably secured foothold for...