The manufacturers of the steel roof truss plates also referred to as gussets or gang nails provide the engineering design for pre fabricated wood trusses.
Steel roof truss spacing.
Their programs will allow for trusses to be placed on 12 foot or even 16 foot centers and their engineers will place their engineer s seal on the drawings to verify.
Roof trusses were usually produced on site in the past.
Truss spacing for metal roof.
If purlins are laying flat on top of the truss 5 or 6 feet is the max on 2x4 s edge up can go to 12 feet or more.
It all comes down to engineering.
The typical standard for the spacing on the roof trusses is 24 inches.
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.
The same concept holds true for roof trusses.
Typically pole barn style buildings in my area have bays distance between trusses of 5 feet to 12 depending on pitch insulation and height.
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.
So the space between rafters can be greater without reducing the maximum span.
Engineers have since determined however that the physical design of a post frame building will allow for standard spacing as great as 12 feet from the center when using high quality metal connector plates and lumber.