Floor joists or beams provide the below surface support for the wood subfloor of a room.
Floor joist sizing uk.
The most common option for your floor joist is your standard 2 6.
Surveyors and structural engineers use data from tables below to help calculate the size of timbers necessary to give adequate support to timber floors.
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.
Looking at this table you will see there is a choice in the size of floor joist 2 x 6 2 x 8 2 x 10 or 2 x 12 and there is a choice in the joist spacing 12 16 or 14.
Choosing the correct floor joist size depends on your building application joist spacing and several other factors these include the length of the span as well as the type and grade of the lumber being used.
The floor joist span tables are based on the loadings given in the amended version of bs 6399 1 which is an imposed load of either a uniformly distributed load of 1 5 kn m or a concentrated load of 1 4 kn.
1 2 timber strength class and joist size automatically calculate sizes suitable for supporting the loads below c16 cost effective for most applications c24 stronger more demanding c14 c18 c22 c27 c30 c35 c40.
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.
Traditionally this material was sold in sawn sizes such as 4 x 2 or 47mm x 100mm now days the uk market is used to offering this material regularised ie it has smooth planed eased edges making it easier to work with and.
Joist span and spacing is set by your local building code.
What size floor joist do i need.
Common joist spacings are 12 inches 304 8 mm 16 inches 406 4 mm and 24 inches 609 6 mm.
Joists are to have minimum end bearing of 40mm.
A 2 8 will provide a few additional benefits and have some advantages but overall the 2 6 is the most commonly used and budget friendly option for constructing your shed floor.
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 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.
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.
