Garage Roof Joist Centres

Surveyors span tables for designing roof rafters.

Garage roof joist centres.

Permissible clear span metres. Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. For pitched roofs flat roofs and ceiling joists. The garage is an existing garage with a flat roof with small slope for drainage.

Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1. Although you can construct a garage using thicker stronger joists 2 inch by 6 inch joists are sufficient for most garages even if you intend to build an attic storage area above your garage. Front of garage has to 8 ft. Half the span means 4 times the load carrying capacity from a strength standpoint the deflection would be 1 16 that of the full span.

It is square 19 6 x19 6 with 2x8 roof joist spacning 19 6 and need a beam support in middle of roof joist. Its a pair of 3x2s on a 2 7m span so maybe a little under sized too. One of the joists in my garage is getting beyond saving and starting to sag so it needs replacing. Rafter and roof joist spacing is only one part of a complex roof design that works together to form a structure that meets building codes and can hold up the weight of the roof and roof load.

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. Dead load per square metre in kn m supported by joists. Ideally i l replace it with something stiffer. If the garage has a simple peaked roof dropping 2x6s free of large knots from the peak and tying them into the center of the ceiling joists would cut the span in half.

But they do tend to space rafters in one of several industry standard increments typically. Fine homebuilding notes that 2 inch by 6 inch garage joists will support a weight of up to 50 pounds per square foot. Builders aren t bound by standard rafter spacing measurements.