×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Spreade Footing Embedment

Spreade Footing Embedment

Spreade Footing Embedment

(OP)
In past codes (UBC) there was a provision for interior isolated spread footings to be buried a minimum of 7" into the surrounding soil to prevent the footing from walking laterally in a seismic event and the supported column failing from the movement. I even believe there was a detail of this condition too. I cannot find such a provision in the current IBC, IRC, or ASCE7.

Did they hide it real well, or just eliminate it?

Mike McCann, PE, SE (WA)


RE: Spreade Footing Embedment

(OP)
In looking at IBC section 1809.4 it seems to say that all footings must penetrate the soil by a minimum of 12", regardless of frost requirements, and section 2304.11.2.7 says that all untreated wood posts sitting on isolated spread footings must be a minimum of 8" above the soil. This would give a minimum depth of 12" to 18" for all interior isolated spread footings depending on whether or not PT posts are used. With the PT posts, the top of the soil could be at the top of the footing.

In Section R403 of the IRC, this specific condition is not addressed from what I can see. It only addresses exterior wall footings, and isolated spread interior footings with a slab.

Am I reading this correctly?

Mike McCann, PE, SE (WA)


RE: Spreade Footing Embedment

(OP)
The IRC in section R403 does not address this particular condition as it is referring to EXTERIOR walls and interior spread footings with slabs on grade.

However, the IBC (1809.4 & 2304.11.2.7)seems to say that the minimum depth of embedment for an isolated spread footing, regardless of frost, is 12 inches, and that the wood posts framing to the footing must either be PT, where the vertical distance soil to wood is 0", or 8" when the wood column is not treated. This would give a minimum interior spread footing depth of 12" or 18", depending on the wood column used.

Am I reading things correctly here?

Mike McCann, PE, SE (WA)


RE: Spreade Footing Embedment

Mike...I read them the same as you; however, I don't have to deal with seismic! Just wind!

As you can see from this, the codes have no real continuity or cross relation....a problem.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources