Foam Insulation question


  #1  
Old 03-31-11, 12:28 PM
L
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Foam Insulation question

Is there any reason why I wouldn't be able to to use 1" rigid foam insulation or Radiant barrier between the floor joists in my crawl space? I planned to seal the edges with spray foam and then run a batt insulation underneath. It would obviously be a lot of work to cut the rigid insul to fit between the joists but in the end I think it would save money over using a DIY spray foam kit or hiring someone.
 
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Old 03-31-11, 12:45 PM
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If it was me, I would buy some 2" XPS foam board (pink or blue) and cut cross-ways to width just under what need for a very tight fit.

Get some expanding foam and apply it to 4' lengths all around where a foam panel would be and immediately force the board up and in to use the foam as a sealer and adhesive. Go and do this to the underside of the subfloor and when it is cured, use a knife to trim it clean to see if there areas to foam later, if necessary.

Forget about the batts since they just hold moisture, bugs and critters and are ineffective if there is any moisture.

Dick
 
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Old 03-31-11, 12:55 PM
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Concrete,
Sounds good, I recently read where a combination of foam and fiberglass were more ideal than either one alone. I'm not sure I'll get a sufficient R-value with just the 2" rigid so thats why I want to add the batts.
 
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Old 03-31-11, 01:43 PM
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After looking at hurricane damage and other mold/moisture problems from leaks, I avoid fiberglass wherever possible. the are R-values and then there are other R-values. As little as 1% moisture trapped in fiberglass can reduce the real insulating value by 50% from the ideal lab tests. Other materials do not have that moisture problem.

Since you have a crawl space that is probably enclosed or protected, the air temperatures are moderated by the soil and do not experience the radical temperature swings elsewhere.

Dick
 
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Old 03-31-11, 02:04 PM
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The r-10 should be fine in your climate as floor insulation is for heat loss and despite your recent weather you really don't get terrible winters in tx.

Bud
 
 

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