Timber Sizes For Pitched Roof

For pitched roofs flat roofs and ceiling joists.

Timber sizes for pitched roof.

To meet the requirements of the c16 timber grade timber is machine graded or visually graded. Roof pitch between 15 and 22 5 degrees with rafter spacing strength. It s often chosen as the standard timber for roof extensions or joist refurbishment as it s the most cost effective internal structural timber. Roof pitch between 15 and 22 5 degrees with rafter spacing strength class c16.

The pitch of the toof is significantly increased to provide additional strength and durability as well as providing a better internal space. C16 timber is commonly used in floor and roof joists for internal building work. Ceiling finishes should be fixed according to the spacing of the support members and the thickness of the sheet. Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees size of rafters in mm roof pitch between 15 and 22 5 degrees with rafter spacing of roof pitch between 22 5 and.

Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings. Rafters are nailed to a wall plate at the top of each supporting walls these are normally 100x75mm 4x3 inches timber embedded on cement mortar on top of the inner skin of a cavity wall or the inner part of a solid wall. 12 5 15mm plasterboard should be fixed at a maximum support spacing of 600mm. Roof pitch between 15 and 22 5 degrees with rafter spacing.

The wider the gap between the rafters the thicker the rafter and lath timbers need to be. It will be all be warm roof insulation above and between with the ceiling plasterboard nailed under the rafters so no ties. My builder would also be delighted to over specify the timber. Plasterboard should be fixed as follows.

Maximum clear span of rafters in metres for roof pitches of between 15 and 45 degrees. Surveyors span tables for designing roof rafters. The building control officer won t specify the timber sizes but seems to be easy going and would be happy to accept generous sizes with c24 timber.