Roof Joist Spacing Uk

In other words you would space a roof joist 15 inches apart from another roof joist but never 17 inches apart.

Roof joist spacing uk.

A roof joist is always spaced no more than 16 inches apart from another roof joist. Sixteen inch oc spacing of ceiling joists made from 2 southern pine allows for a maximum 13 inch span length. Span calculator for wood joists and rafters also available for the. Usually 400 450 or 600mm but any value can be used up to 610mm max.

Surveyors span tables for designing roof rafters. Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet. Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. Permissible clear span metres.

If the roof is not completely square you can decrease the space between joists but never increase the space. For pitched roofs flat roofs and ceiling joists. Dead load per square metre in kn m supported by joists. The same concept holds true for roof trusses.

Whilst you could go wider in theory with deeper rafters the spacing is limited by tiling batten span. For example the highlighted cell below shows that a 2 x 6 southern yellow pine joist with a grade of 2 and spaced 24 apart can have a maximum span of 10 feet 0 inches 10 0 if you are designing your structure to support a plaster ceiling. This will support a room ceiling that is 10 feet long on one side as in 10 foot by 15 foot or 10 foot by 17 foot rooms which is a standard dimension for many rooms in residential construction. When starting to space out the roof joists always start at the end of the roof.

You could set out the joists at normal centres and cut in trimmers to create the width opening you need then pack out the sides. A clear span of 2 69m is possible using 6 x 2 at 600centres for a slate tiled roof. So the space between rafters can be greater without reducing the maximum span. Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1.

Spacing in exterior exposure. 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.