Floor Joist Rule Of Thumb

For each additional 2 of depth add 2 of span up to 12 deep.

Floor joist rule of thumb. Assume that i have an attic which currently has 2x6 joists on 16 inch centers. If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s. A joist is a horizontal structural member used in framing to span an open space often between beams that subsequently transfer loads to vertical members. The american wood council states that cantilevers are limited to 1 4 the span of the joists.

Follow the rules to keep your floor solid. Mike standard deck framing for joists of various depths you don t give the depth nor span of your porch floor joists are in the article above. Just specifying 12 oc joist spacing is not enough to even make a wild guess at spans allowed. The rule of thumb for the depth of common joists is to take half span in feet.

You must use at least five framing nails to attach the rim joist to the ends of your joists. On 2019 03 02 by mod using 3 4 porch floor boards over joists with what spacing. 8 2 x 2 12 maximum allowable span for a generic deck floor joist a look at an actual current joist span table will show that depending on the wood species the allowable spans for a 2x8 floor joists with 40 pound live load with deflection limit of span 360 ranges from 10 5 western red cedar to 12 9 doug fir larch. E is chief operating officer of structural affiliates international inc in nashville.

Ioannides ph d s e is president and john l. Many building departments limit joist cantilevers to 24 maximum. Steel construction rules of thumb. When incorporated into a floor framing system joists serve to provide stiffness to the subfloor sheathing allowing it to function as a horizontal diaphragm joists are often doubled or tripled placed side by side where conditions warrant.

Light gauge steel joists or trusses 6 deep span 10. You can notch and bore joists without sacrificing critical strength but you must follow the rules.