The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.
Timber roof spars.
Pitched roof timber sizes.
Lifetime coverage on shingles requires the use of gaf lifetime shingles only.
Timber framed and historic buildings may be framed with principal rafters or timber roof trusses.
Imposed loads of 1 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude.
Surveyors span tables for designing roof rafters.
The edge of a roof which runs from eaves to ridge at a gable.
Strengthening a timber framed roof can become necessary for a number of reasons.
All the figures are based on roofing tiles or slates laid on timber laths over sarking felt.
1 lifetime refers to the length of warranty coverage provided and means as long as the original individual owner s of a single family detached residence or the eligible second owner s owns the property where the qualifying gaf products are installed.
2 part of a flat roof structure that receives the ends of the flat roof joists.
Cutting and laying roof rafters for the vaulted roof duration.
Imposed loads of 0 75 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude does not exceed 100 metres refer to bs 6399 3.
3 part of a suspended timber floor construction that provides a level.
Joists spars treated timber 3 6m 12ft 200mmx50mm 8 x2.
1 part of a pitched roof construction that receives the feet of the spars sp ars and ceiling joist ends.
Modern timber roofs are mostly framed with pairs of common rafters or prefabricated wooden trusses fastened together with truss connector plates.
Birdsmouth joint how to cut a birdsmouth and how to cut and install roofing rafters and joists.
8 2 most commonly used in the construction of floor joists and roof applications but very adaptable and can be used in many other areas this size is great for raised beds all treated and good for outdoor use.
Replacement roof tiles may be heavier than those the structure was designed to support timbers may have become rotten other planned structural alterations may necessitate strengthening or perhaps the structure was not strong enough in the first place.
Ideal for structural and gardening projects.
For other owners structures lifetime coverage is not applicable.
In this diy guide you will learn how to install a roofing joist or rafter that includes how to work out the pitch of a roof cut a ridge or plumb cut at the correct angle work out the correct length of joist you need and the exact location for a birds mouth joint how to correctly cut a birds.