Timber Floor Joist Sizes

See the image below for an example of joists spaced 16 on center 16 o c.

Timber floor joist sizes.

While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length. Floor joists or beams provide the below surface support for the wood subfloor of a room. This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction. Though joists may be any size that you desire using typical floor joist and beam specifications ensures that you can find hardware to fit the joists and that the floor provides adequate support for furniture and other items in a room.

Joist span and spacing is set by your local building code. Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors. Since the example house we are designing for is 12 feet wide we need to find in the floor joist span table a joist size and centering that can span 12 or wider. This span table is to the format and methodology given in bs 5268 7 1.

These spans were calculated using our floor joist calculation engine. Find the column for your dead load and spacing and the row for your timber size to find the permissible clear span in metres. The floor joist spacing is the distance between the centers of any two installed joists.