ICF Footing Size and Soil Strength
Last Post 20 Jul 2011 11:30 AM by Jerry Coombs. 8 Replies.
Printer Friendly
Sort:
PrevPrev NextNext
You are not authorized to post a reply.
Author Messages
4000psiUser is Offline
New Member
New Member
Send Private Message
Posts:1

--
27 Jun 2011 10:21 AM
Looking for some help on sizing of footing for a residential ICF build. 

Existing soils at footing depth consist of silty-clay. 

With the addition of subbase material such as crushed non compactable stone can the the size of the footing be reduced?

When adding subbase below footing what depth would be appropriate.  12'' ???  

The home will have a full basement and 1st floor.

Exterior Walls will be poured 6'' walls to the eaves. 

Backfill will be placed around the basement to a depth of 7 feet

The area is northern New York with frost depth to 4 fbg.

Seismically the area falls within Zone C of NY seismic Map.

Anyhelp on subbase material, footing size and reinforcemnt would be helpful


Thanks In Advance

4000PSI
lzerarcUser is Offline
Basic Member
Basic Member
Send Private Message
Posts:423

--
27 Jun 2011 10:37 AM
You really need to have an engineer in your area size the footings and spec the reinforcement.  It may even be something you need to submit to the building official for approval as well.
smartwallUser is Offline
Advanced Member
Advanced Member
Send Private Message
Posts:579
Avatar

--
28 Jun 2011 08:06 AM
I'm in upstate NY an I generally use 20" footings with a 6" subbase. The only time I change this set up is if we find wet conditions when the site is excavated and you only know that is when you dig
smartwallUser is Offline
Advanced Member
Advanced Member
Send Private Message
Posts:579
Avatar

--
28 Jun 2011 08:14 AM
On reinforcing the" presciptive method" is the place to determine the reinforcing needed. You didn't say how high the foundation will be.
Jerry D. Coombs, PEUser is Offline
Basic Member
Basic Member
Send Private Message
Posts:138
Avatar

--
28 Jun 2011 12:18 PM
Silty clay covers a lot of variables. Depending on where you are, you can have a great suitable base, while other places, not at all. And any time you're doing that much backfill, I'd have an engineer look at it. It's worth the investment.
Jerry D. Coombs, P.E.
Coombs Engineering, P.C.

You can have with quality; You can have it fast; You can have it cheap. Pick any two.
dhoughUser is Offline
New Member
New Member
Send Private Message
Posts:7

--
19 Jul 2011 08:10 PM
I was told by my engineer that without soil borings he had to assume 2000psi, and size for that. In one hand cost of extra concrete, other cost of soil borings.
Jerry D. Coombs, PEUser is Offline
Basic Member
Basic Member
Send Private Message
Posts:138
Avatar

--
20 Jul 2011 09:44 AM
Supposition will still be a guess as to effectiveness. It's better to go on solid information. you might still have to pay for the concrete, but it will be worth it. Peace of mind for all.
I am frequently confronted with the reluctance to do a soil report because of cost. About $1500 here. About 0.6% of the cost, on average. Then they'll spend that much on the tile in the entry way. I will use very conservative numbers as I don't want that liability, and will most assuredly cost more. Remember the foundation supports it all. An inadequate foundation, and that tile is destroyed.
Jerry D. Coombs, P.E.
Coombs Engineering, P.C.

You can have with quality; You can have it fast; You can have it cheap. Pick any two.
Baldwin2014User is Offline
Basic Member
Basic Member
Send Private Message
Posts:122

--
20 Jul 2011 11:18 AM
Dear 4000psi....

change your name to something less confusing please ... i thought you figured out your soil to be 4000psi... it took me a few seconds...

Here's what IRC 2009 calls for... Maybe someone around here can confirm my interpretation...

Jerry D. Coombs, PEUser is Offline
Basic Member
Basic Member
Send Private Message
Posts:138
Avatar

--
20 Jul 2011 11:30 AM
4000 psi soil? Pretty hefty! :o) I think 4000 psf. I thought it was his concrete strength, but figured it out. Thought it was a cool moniker.
Anyway, those classifications still need to be determined by someone who knows, but local building people may know. It still doesn't change that a soil report will likely increase it. The people writing the codes are as conservative as engineers.
Jerry D. Coombs, P.E.
Coombs Engineering, P.C.

You can have with quality; You can have it fast; You can have it cheap. Pick any two.
You are not authorized to post a reply.

Active Forums 4.1
Membership Membership: Latest New User Latest: Hader New Today New Today: 0 New Yesterday New Yesterday: 4 User Count Overall: 28700
People Online People Online: Visitors Visitors: 200 Members Members: 15 Total Total: 215

GreenBuildingTalk

Welcome to GreenBuildingTalk, the largest, most active forum on green building. While you can browse the site as a guest, you need to register in order to post.

Register Member Login Forum Home

Search Directory

Professionals Products

Get Free Quotes

Tell us about your building project and get free quotes from green building professionals. It's fast & easy! Click here to get your free quote.

Site Sponsors

For Advertising Info:
Call 866-316-5300 or 312-223-1600

Professionals Serving Your Area:

Newsletter

Read the latest GBT Newsletter!

Copyright 2011 by BuildCentral, Inc.   Terms Of Use  Privacy Statement  Free Quotes  Professional Directory  Advertising Programs