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Posted: Jul 07, 2007 04:20 PM	2" of 2.7 roofing foam under basment slab got a 3200 sq foot geothermal modular 2 story home. open cell, closed cell, and cellulose. builder wants foam under the basement floor to stop the heat sink effect of the winter. I would tamp the dirt flat. Then I would apply 2" of 2.7 closed cell on top of tyvek or geotextile fabric. can i use 1.9lb closed cell? the compressive strength of the roofing foam is > than 50 psi. the 1.9lb C.C. has a compresive strength of only about 25 psi. 2" of either foam gives me a vapor barrier. what can I use for this 2300 sq ft basement footprint? seasoned veterns I need your imput!
Luke Kujacznski Posted: Jul 07, 2007 07:51 PM	I have done a lot of these. 2lb foam is fine. The only place I put high density foam is under areas that area going to have pillings or weight barring walls put over them. Make sense? Also if you are good you don't need to put a fabric down first, this also makes it hard because as the foam cures it tends to pull the fabrick up. I like to spray on gravel or sand because it doesn't take much to dry the top out and you don't use that much foam.
Posted: Jul 08, 2007 08:34 AM	THANKS LUKE! I WILL USE THE 1.9 FOAM. 5 FOOT DOWN IT WILL BE MOIST CLAY. SAND SOUNDS LIKE A BETTER IDEA.1/2' OF SAND? 1" OF SAND? MIDDAY SUN ON THE SAND SHOULD HELP DRY IT OUT. COULD YOU BE A LITTLE MORE SPECIFIC ON THE FABRIC BEING PULLED UP BY THE FOAM? PULL UP IN CERTAIN SPOTS? GOTTA HAVE TWO PLANS. PLAN A IS SAND, PLAN B IS FABRIC. IT HELPS TO KNOW WHAT CAN GO WRONG. ANY OTHER FOAM BASEMENT EXPERIENCES OUT THERE?

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Comments

Posted: Jul 07, 2007 04:20 PM

2" of 2.7 roofing foam under basment slab

got a 3200 sq foot geothermal modular 2 story home. open cell, closed cell, and cellulose.
builder wants foam under the basement floor to stop the heat sink effect of the winter. I would tamp the dirt flat. Then I would apply
2" of 2.7 closed cell on top of tyvek or geotextile fabric. can i use 1.9lb closed cell? the compressive strength of the roofing foam is > than 50 psi. the 1.9lb C.C. has a compresive strength of only about 25 psi.
2" of either foam gives me a vapor barrier.
what can I use for this 2300 sq ft basement footprint? seasoned veterns I need your imput!

Luke Kujacznski

Posted: Jul 07, 2007 07:51 PM

I have done a lot of these. 2lb foam is fine. The only place I put high density foam is under areas that area going to have pillings or weight barring walls put over them. Make sense? Also if you are good you don't need to put a fabric down first, this also makes it hard because as the foam cures it tends to pull the fabrick up. I like to spray on gravel or sand because it doesn't take much to dry the top out and you don't use that much foam.

Posted: Jul 08, 2007 08:34 AM

THANKS LUKE! I WILL USE THE 1.9 FOAM. 5 FOOT DOWN IT WILL BE MOIST CLAY. SAND SOUNDS LIKE A BETTER IDEA.1/2' OF SAND? 1" OF SAND? MIDDAY SUN ON THE SAND SHOULD HELP DRY IT OUT. COULD YOU BE A LITTLE MORE SPECIFIC ON THE FABRIC BEING PULLED UP BY THE FOAM? PULL UP IN CERTAIN SPOTS?
GOTTA HAVE TWO PLANS. PLAN A IS SAND, PLAN B IS FABRIC. IT HELPS TO KNOW WHAT CAN GO WRONG.

ANY OTHER FOAM BASEMENT EXPERIENCES OUT THERE?

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