A clear span of 2 69m is possible using 6 x 2 at 600centres for a slate tiled roof.
Roof joist spacing uk.
Usually 400 450 or 600mm but any value can be used up to 610mm max.
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.
In other words you would space a roof joist 15 inches apart from another roof joist but never 17 inches apart.
So the space between rafters can be greater without reducing the maximum span.
For pitched roofs flat roofs and ceiling joists.
Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1.
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.
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.
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.
Live load psf dead load psf span calculator for wood joists and rafters available for the iphone.
Surveyors span tables for designing roof rafters.
If the roof is not completely square you can decrease the space between joists but never increase the space.
Dead load per square metre in kn m supported by joists.
Measure from the ends.
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.
Permissible clear span metres.
Spacing in exterior exposure.
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.
When starting to space out the roof joists always start at the end of the roof.