Size Of Timber Floor Joists

Joist span and spacing is set by your local building code.

Size of timber floor joists.

When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started. A structure with a 10 foot 3 05 m length and joists set 12 inches 304 8 mm apart would require using a floor joist size of 2 x 8 50 8 x 203 mm. 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. These spans were calculated using our floor joist calculation engine.

Click on a span to generate a full calculation you can adjust the exact span. Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors. In fact there are no standard joist sizes and the joist spacing depth thickness wood type and load capacity must also be considered before ordering. If the joist spacing will be 16 inches 406 4 mm a joist size of 2 x 8 should be used even if the length is only 8 feet 2 44 m.

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. These tables can help calculate whether floor joists are strong enough to support themselves and the load they carry without the help of any walls underneath. Floor joists capacities carrying capacities of domestic timber floor joists grade c in metric units floors live loads floors and minimum uniformly distributed live loads maximum size of duct or pipe through steel joists k series joists and maximum size of ducts and pipes. Floor joists or beams provide the below surface support for the wood subfloor of a room.

Floor joists are typically 2 by 8s 2 by 10s or 2 by 12s. A floor s framework is made up mostly of wooden joists that run parallel to one another at regular intervals. 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. This span table is to the format and methodology given in bs 5268 7 1.

Some newer homes have manufactured i beam shaped joists. Ceiling joists are usually 2 by 6s or sometimes 2 by 4s if it is an older home. All the figures are based on normal domestic floor loadings where the floor construction is typically 18 25mm floor boards sheets with up to 12 5mm thick plasterboard and skim underneath.