Replies

1. 
   Guest_ | Feb 05, 2000 11:14pm | #1

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   Chuck. All 4 model building codes require that footings extend to or below the frost line. Only the BOCA code says that the footings do not have to extend to the frost line "...when otherwise protected from frost..." The code does not say what "otherwise procted" means. The methods and materials used to frost-protect the footings are left to the designer or builder.

   Keep in mind that there are three conditions necessary for frost to occur: 1) frost-susceptible soil, 2) enough water, and 3) temperatures low enough to freeze the water soil combination. GeneL.

1. 
   Guest_ | Feb 06, 2000 07:45am | #2

   *At least in my area, hardpan is densly packed soil, not rock. It usually happens on agricultural ground that has been worked with heavy machinery for many years. If that is the case, you must go below the frost line.If you're building on solid rock, then anchoring your foundation to the rock should do the job.

1. 
   Guest_ | Feb 07, 2000 12:51pm | #3

   *Chuck, The CABO model code says that footings have to extend below frost line EXCEPT when on solid rock or when otherwise protected from frost, which could mean various things. There are lots of houses in Alaska, even as far north as Fairbanks, that use the Frost Protected Shallow Foundation system that has been explained in numerous articles in FHB, JLC and others. The National Association of Homebuilders has a good publication on this system. It works, I have one on my house in Alaska.Tom Laing

2. 
   chuck_sindelar | Feb 08, 2000 11:58am | #4

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   Tom,

   I'm having a heck of a time getting this to you. So here goes again. Thanks for the info! How can I get a copy of the publication on The Frost Protected Foundation Systems from The National Association of Homebuilders? I've been unable to find in on the web. Also, what does JLC represent? Thanks again for all your help!

   Chuck
   from Nevada

3. 
   Guest_ | Feb 09, 2000 03:48am | #5

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   Journal of Light Construction

   View Image

4. 
   Kevin_Powell | Feb 09, 2000 10:42pm | #6

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   For those wanting the NAHB Research Center publication, "Design Guide for Frost Protected Shallow Foundations", it can be ordered from the web at http://www.nahbrc.org or you can call Toolbase Hotline at 800-898-2842. The cost is $30.

   The web site for our parent organization, NAHB, is http://www.nahb.com.

5. 
   chuck_sindelar | Feb 09, 2000 10:42pm | #7

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   Putting a foundation footing below the frost line is supposed to protect it from frost heave. In the region I live that is three feet below finish grade. Is this a rule that applies to all soils or just soils that have a potential to heave? We live in a region that consists of hardpan (rock).

   Chuck Sindelar
   02/04/00