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. E is chief operating officer of structural affiliates international inc in nashville. 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.

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. If your home is more than 20 years old your floor joists are most likely solid wood 2x8s 2x10s or 2x12s. Ioannides ph d s e is president and john l. 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. Many building departments limit joist cantilevers to 24 maximum. You must use at least five framing nails to attach the rim joist to the ends of your joists. Steel construction rules of thumb.

E g for a span of 18 feet half this is 9 add 2 which giv. 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. 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.

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. If i sister a 2x8 to each 2x6 meaning that the bottoms of the joists line up but the top of the 2x8 is approximately 2 inches above the top of the 2x6 is there a span table for such a situation or any rule of thumb for estimating strength as per code.