Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1.
Roof joist spacing uk.
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.
For pitched roofs flat roofs and ceiling joists.
Dead load per square metre in kn m supported by joists.
A roof joist is always spaced no more than 16 inches apart from another roof joist.
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.
When starting to space out the roof joists always start at the end of the roof.
Sixteen inch oc spacing of ceiling joists made from 2 southern pine allows for a maximum 13 inch span length.
Whilst you could go wider in theory with deeper rafters the spacing is limited by tiling batten span.
Permissible clear span metres.
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.
Span calculator for wood joists and rafters also available for the.
Surveyors span tables for designing roof rafters.
Live load psf dead load psf span calculator for wood joists and rafters available for the iphone.
Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600.
In other words you would space a roof joist 15 inches apart from another roof joist but never 17 inches apart.
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.
This is the distance between joist centres.
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.
So the space between rafters can be greater without reducing the maximum span.
A clear span of 2 69m is possible using 6 x 2 at 600centres for a slate tiled roof.
Usually 400 450 or 600mm but any value can be used up to 610mm max.
The same concept holds true for roof trusses.
