This is the distance between joist centres.
Timber roof joists sizes.
They can be trimmed on site and long lengths allow ceilings and floors to be designed with fewer pieces saving installation time.
For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine.
Permissible clear span metres.
Size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42 47 x 195 4 41 4 31 3 92 47 x 220 5 04 4 85 4 41 75 x 170 4 50.
Standard size of joists though there is no standard joist size for the ceilings in all buildings most average homes use ceiling joists in a board size of 2 by 6 inches.
For pitched roofs flat roofs and ceiling joists.
Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600.
Section 91 2308 8 2 joists 91 2308 10 4 2 rafters b notches at the ends of joists or rafters shall not exceed one fourth the depth.
The lengths and sizes of joists vary depending on the species and quality of the lumber used.
Lp solidstart i joist benefits.
The range of joist sizes used in homes varies though between 2 by 4 inches and 2 by 12 inches.
Lp solidstart i joists are more versatile than open web floor trusses and more uniform and dimensionally stable than lumber.
Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1.
Holes bored in the joists or rafters shall not be within 2 inches of the top or bottom and the diameter of any such hole shall not exceed one third the depth of the member.
Dead load per square metre in kn m supported by joists.
Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors.
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.
Surveyors span tables for designing roof rafters.