**Originally Posted By: roconnor**

**This post was automatically imported from our archived forum.**

and

stability. Dont confuse the two.

Strength: Cantilever span should be no more than 1/4 the allowable joist span rating ... for bending resistance.

Stability: Cantilever span should be no more than 1/3 the back span ... to prevent uplift

[from IRC R502.3.3 ... more restrictive than the old stability rule of 1-out & 2-in ... or cantilever no more than 1/3 total length]

So a typical 2x8 DF#2 joist with a span rating of say 12-feet should not cantilever out more than 3-feet (1/4 span rating), and for stability it should extend into the house at least 9-feet [cantilever 1/3 the back span ... or back span 3 times the cantilever]

Note that those rules of thumb are only for nominal snow load areas, and do not apply to cantilevers supporting an outside wall ... where the limit of the cantilever would be 2-4 times the joist depth depending on the details.

Hope that helps ... ![icon_wink.gif](upload://ssT9V5t45yjlgXqiFRXL04eXtqw.gif)

--

Robert O'Connor, PE

Eagle Engineering ?

Eagle Eye Inspections ?

NACHI Education Committee

I am absolutely amazed sometimes by how much thought goes into doing things wrong