Using a combination of rafters and purlins is common.
Rafter spacing for tile roof.
The same concept holds true for roof trusses.
To ensure this the battens should be at least 1 2m long.
Rafter spacing rafters must be strong enough to hold the roof sheathing and the shingles.
So the space between rafters can be greater without reducing the maximum span.
Use these two tables for roof rafters with a slope of 3 in 12 or less.
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.
The typical spacing standards for residential and commercial buildings are about 1 to 2 foot.
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.
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.
Battens should be fixed to rafters set at centres not more than 600 mm apart and should span at least 3 rafters.
If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.
With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel.
Typical rafter spacing codes will specify a minimum spacing of 16 inches 19 2 inches or 24 inches.