Garage Roof Joist Spacing

So the space between rafters can be greater without reducing the maximum span.

Garage roof joist spacing.

A roof joist is always spaced no more than 16 inches apart from another roof joist. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. 2 8 s come standard at 1 inch thick. Joist spacing of 24 inches is allowed for spans between 16 to 20 feet using 2 inch by 10 inch lumber of these three grades.

Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. This is the distance between joist centres. 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. Dead load per square metre in kn m supported by joists.

Two options that arise could be your wider 24 and your narrower 12 options for spacing. Variations in ceiling construction nonparallel ceiling joist designs require additional support construction in the ceiling. The same concept holds true for roof trusses. For example the highlighted cell below shows that a 2 x 6 southern yellow pine joist with a grade of 2 and spaced 24 apart can have a maximum span of 10 feet 0 inches 10 0 if you are designing your structure to support a plaster ceiling.

The table states that 2 x 6 rafters spaced 16 inches on center o c can span a maximum distance of 13 feet 5 inches. Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1. If this is the case with your structure use the floor joist table to determine maximum joist length load. In other words you would space a roof joist 15 inches apart from another roof joist but never 17 inches apart.

Pole barn roof truss spacing generally tens to operate according to similar spacing principles though there are some proponents of having higher pole barn roof truss spacing. Another option are 2 x 8 rafters spaced 24 inches o c. 2x8s are used frequently for these projects. In many circumstances 16 inches would be your standard spacing for shed floor joist but this is just a rough guideline.

In making your choice consider how you will insulate your insulate your roof. 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. Especially when steel roof truss spacing is concerned some engineers would argue that it is possible to only have a roof truss spacing of four feet off center even eight feet has been suggested.