If you can stop someone in the store to help explain the inconsistency they ll start throwing around a few words like nominal sizes and actual sizes and softwood lumber and hardwood lumber.
Actual size of 2x8 typical floor joist.
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.
Something doesn t quite match up.
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.
Maximum floor joist span for no.
1 psf lb f ft 2 47 88 n m 2.
Dead load weight of structure and fixed loads 10 lbs ft 2.
Mitek usp makes one for each joist size between 2x4 and 2x10 the one for 2x10s also works for 2x12s in its jlif product.
If the design calls for concealed or in turned flange hangers simpson strong tie only makes two sizes in its luc product one for 2x6 and 2x8 joists and a larger size for 2x10 and 2x12 joists.
The maximum span distance for 12 inch spacing is greater by as much as 30 percent compared to 24 inch.
Floor joists or beams provide the below surface support for the wood subfloor of a room.
1 ft 0 3048 m.
The larger the deck the larger the joists.
Joists that are closer together can support more weight which allows the joists to span a longer distance than joists spaced further apart.
A 2x8 up to 12 feet.
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.
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.
True floor joist span calculations can only be made by a structural engineer or contractor.
Actual dimensional lumber is cut to a specific length width and depth.
2 grade of douglas fir are indicated below.
Joist span and spacing is set by your local building code.
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.
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.
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.
Measure the actual width and thickness of a pine board like a 2x4 and then look at the sign above the rack.
However there is a difference between the nominal size what the lumber is referred to and the actual size.
