Garage Roof Joist Spacing

Two options that arise could be your wider 24 and your narrower 12 options for spacing.

Garage roof joist spacing.

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. In making your choice consider how you will insulate your insulate your roof. Permissible clear span metres. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.

In other words you would space a roof joist 15 inches apart from another roof joist but never 17 inches apart. 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. 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. Variations in ceiling construction nonparallel ceiling joist designs require additional support construction in the ceiling.

A roof joist is always spaced no more than 16 inches apart from another roof joist. Another option are 2 x 8 rafters spaced 24 inches o c. Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1. Dead load per square metre in kn m supported by joists.

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. This is the distance between joist centres. So the space between rafters can be greater without reducing the maximum span. Usually 400 450 or 600mm but any value can be used up to 610mm max.

The same concept holds true for roof trusses. 2 8 s come standard at 1 inch thick. 2x8s are used frequently for these projects. 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.

In many circumstances 16 inches would be your standard spacing for shed floor joist but this is just a rough guideline. If this is the case with your structure use the floor joist table to determine maximum joist length load. If the roof is not completely square you can decrease the space between joists but never increase the space.