As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.
Shed roof rafters spacing.
Use these two tables for roof rafters with a slope of 3 in 12 or less.
There is no standard spacing it depends on what size of rafters you want to use and the span of your shed.
This is most likely the standard size that you will find on pre made roof trusses.
The same concept holds true for roof trusses.
If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.
It is possible to calculate a birdsmouth near the top of the rafter for a freestanding shed roof by checking the kneewall checkbox and entering a setback for the kneewall that positions the upper birdsmouth in the desired location.
For instance 2 grade 2x4s at 16 on center will span just over 9.
As most building these days are using those pre made trusses on the roof 24 inches become the main size for any roofing construction when it comes to its truss installation.
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.
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.
If you get premium kiln dried lumber then you could span 10 5 with the same size of lumber and rafter spacing.
For standard shed roof rafter spacing see rafter span chart.
So the space between rafters can be greater without reducing the maximum span.