So the space between rafters can be greater without reducing the maximum span.
Roof strut spacing.
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.
The same concept holds true for roof trusses.
Struts must be either vertical perpendicular to the rafters or at an angle to the vertical which does not exceed 35 o.
Typical roof truss spacing means that they are usually about 24 inches from centre which means at the centre of one truss there will be a two foot gap or twenty four inch gap until the centre of the next truss.
They should have anti slip blocks where necessary to prevent them sliding horizontally.
To determine how many trusses to create you will first need to measure both the width and the length of the structure you are building.
The trusses should be a little longer than the exact width to allow for overhang and you will need sufficient trusses to mount across the length.
They are birdsmouthed or halved to fit underpurlins as shown below.
These standards are as follows.