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Re: Using Geofoam under parking lots

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Title: Using Geofoam under parking lots
        10 psi is not strong enough to handle traffic loads!!  This 10 psi material is virtually useless for structural applications; it's too strong to use as void form and not strong enough to resist structural loads.
        You will also need to design the depth of the insulation below grade.  The equation I have used in the past for assessing the pressure at a depth generated by wheel loads is by Boussinesq.  This equation is used for determining pressures on buried pipelines among other things.  This plus the dead weight of soil above the insulation will determine the strength of insulation you require.  I would expect that a practical design would involve insulation strength in the order of 35 to 50 psi buried at a depth of two feet below grade give or take.
        Hope this is helpful.
H. Daryl Richardson
----- Original Message -----
From: Mark
Sent: Wednesday, August 17, 2005 1:08 PM
Subject: Using Geofoam under parking lots

Project: Snow Melting under parking lot and alleyway.  The kicker is that occasionally a 15-ton crane to remove rooftop equipment, etc. sets up in the alleyway.

The manufacturers of the hydronic snow melt system require insulation under their tubing because the water table is within 8 feet.  After some research, I've found that GeoFoam is used under highways, bridges, and abutments.  This sounds like it might be the stuff to use.  I've gone to several websites (,,, and a couple of manufacturer's sites).  Alas, I still don't have a good handle on this. 

Has anyone used this under roadways?  Is 10psi flexural strength really strong enough to support heavy vehicles?

Thanks in advance,
Mark Jones