Size Of Timber Floor Joists

The wood boards used as floor joists generally range in size from no smaller than 2 by 4 inches to no larger than 2 by 12 inches.

Size of timber floor joists. The following table gives details of allowable spans and spacing between joists for the most common timber sizes used in floor construction. 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. Two by 6 inches is a joist size frequently used in both indoor floors and as deck joists. 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.

The larger the deck the larger the joists. 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. Bci joists are specially constructed i joists with flanges made from strong versa lam laminated veneer lumber with oriented stranded board webs and approved waterproof structural adhesives providing outstanding strength and durability. 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.

In joist sizes the larger size such as 6 inches represents the height of the joists while the 2 inch size represents the. 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. Engineered wood products ewp span and size charts for bci joists. 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.

For best results refer to our wood and composite deck joist span table. This span table is to the format and methodology given in bs 5268 7 1. Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors. 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.

Click on a span to generate a full calculation you can adjust the exact span. Joist span and spacing is set by your local building code. In typical deck construction with a ledger on one side of the joist and beam on the other the size of the joists is driven by the size of the deck and based on the general maximum spans mentioned above.