Anything beyond that you are looking at using 2x6s for most sheds.
Skillion roof rafter span tables.
Table 33 bearers supporting two storey loadbearing walls lower floor load width 900mm or 1800mm continued seasoned hardwood f17.
Choose rafter spacing from table 10 1 the options are 480 600 or 900 mm.
Step 1 rafter spacing.
Skillion lean to roof profile diagram quest.
Sheet roofing tiled roofing roof load width rlw mm 1500 2100 4500 7500 1500 2100 4500 7500.
Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.
Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.
Skillion roof rafter detail diagram with all dimensions and birds mouths scale.
Maximum span of bearer mm upper floor load width 3600mm continued continuous spans.
Select output fraction precision decimal inch or metric mm.
This is a heavy roof so the 1200 mm column on the right side of the table is excluded it only applies to light roofs.
If you look at the rafter span chart you ll notice that 2x4s can be used for rafters on spans up to 11.
The pitch and span of your roof will dictate how long of a rafter you ll need use maximum span calculator to help you find your rafter size.