For sheet roofed houses with 900 mm rafter spacing in wind classification n4 or c2 the minimum size of f5 or mgp 10 rafters or top chords shall be 90 x 45 mm.
Roof rafter spacing australia.
Loads are calculated in accordance with table 3 1 of as nzs 1170 1 2002.
Dead load weight of structure and fixed loads 15 lbs ft 2.
Our roof rafter calculator tools are handy for calculating the number of rafters needed rafter length calculator lineal feet of rafter board feed in ridge and sub facia and the total board feet in the roof.
This is set by the roof use you selected in the previous screen and cannot be modified.
Design of single span rafters in roofs in houses office buidlings schools and other structures.
The maximum overhang of house rafters or trusses shall not exceed 750 mm from outside of top plate to end of rafter truss.
3 for design parameters refer to figure 6 22 as1684 2 and 3.
Pitching beams 23 common installation details 25 notches cuts and holes in beams.
Roof area 49 69m rafters 14 rafter spacing 763 5 adjusted to fit evenly next larger spacing 827 1 next smaller 708 9.
2 are indicated below.
3 4 5 x 12 pitch rises that much per foot of distance on the ceiling 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.
Member span is not suitable for rafter spacing greater than 600mm.
The same concept holds true for roof trusses.
1 psf lb f ft 2 47 88 n m 2.
Rafters 12 ceiling joists 15 hanging beams member16 underpurlins 17 strutting beams 18 roof beams 20 verandah beams 22 garage roof.
Live load is weight of furniture wind snow and more.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
Wind classification 1 n2.
Measure the ceiling joist to a point or to center and then plumb to the rafter and do the math.
Use these two tables for roof rafters with a slope of 3 in 12 or less.
For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2.
1 ft 0 3048 m.
Rise and run means that a 6 12 pitch roof has 6 of rise vertical for each foot of run horizontal.
Tables such as those for rafters.
So the space between rafters can be greater without reducing the maximum span.
