Rafter Cantilever

Question Icon
Posted by: from Belleville
7/3/2013 at 5:31:39 PM

What is the cantilever ratio for a 2x8 rafter?

User Icon
Date/Time7/3/2013 at 7:03:57 PM

Are we talking about a rafter or a truss? Or floor joist?

Need a lot more info on this one to be able to answer.

User Icon
Josh in Belleville
Date/Time7/3/2013 at 7:26:03 PM

It is a 2x8 rafter for a deck roof hanging from a ledger board against the house sitting on a 3 ply 2x10 beam that is 12 feet away from the house.

I need to know the maximum over hang allowed.

User Icon
Date/Time7/3/2013 at 7:31:16 PM

If you are talking about a structural member, like a floor joist. The general rule is 1/3 of the length unsupported, although a 1/4 the length is better. This also assumes that it is installed and tied into the existing structure properly.

As far as the building code, it will depend on the situation and there are limits. For actual roof rafters, they usually overhang any were from 12" - 48" and the 1/3 rule should be fine.

User Icon
Josh in Belleville
Date/Time7/3/2013 at 7:40:37 PM

Right now it has a 32" over hang with is better than a 1/4 ratio and the inspector is saying it might not be up to code but he gives no definite answer.

User Icon
Date/Time7/3/2013 at 7:56:15 PM

Your inspector is suppose to know that!!!! Every city has its own rules when it comes to decks, so I wouldn't be able to give you a definite answer.

A 32" overhang over a 12' distance should be fine, but it has to be attached to the ledger board properly. Maybe that is what he is questioning.

User Icon
Josh in Belleville
Date/Time7/3/2013 at 8:04:08 PM

I'm a framer by trade and this guy is an idiot but he has requested the rafters get hangers to the house and said to check if the overhang meets code so was looking for more info since I've never had this problem before.

User Icon
Date/Time7/4/2013 at 10:13:33 AM

it will be 1:4

User Icon
Date/Time7/7/2013 at 9:34:07 AM

The roof rafter has to be connected to the ledger board with hangers (use structural fastners) and the 1:4 rule would suffice.



Search the TrustedPros directory and discover the best contractors in your area.

Find your home service pro
Great renovations start with a great contractor.

Since 2004, TrustedPros has been helping homeowners find the right contractor for their home improvements and repairs.

Post Your Project

Within hours you'll be comparing offers from top-rated professionals. It's free to post and you're under no obligation to hire.

Trustedpros Inc. does not warrant the accuracy, completeness, safety, legality or usefulness of any Content, or Whether Content is Current and up-to-date, and TrustedPros Inc. Shall have no liability whatsoever with respect to your use or reliance upon any content or for content being removed or otherwise ceasing to be available. Please refer to the terms and conditions of use of this websites for more details.

It appears you may be located in the US

TrustedPros is designed to deliver results targeted to your location.

Get Free Estimates

Post your project and compare offers from top-rated pros.