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Maximum thickness allowed Post New Topic | Post Reply
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Richard Russell
Posted: Sep 24, 2007 09:13 AM
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Maximum thickness allowed
Is there any more current info on maximum thickness allowed by building codes for a spray foam wall? On reading the codes, as well as past posts here, it seems that code allows only the thickness that has been tested, but the test facilities can't handle more than 4" thickness. The question remains as to how to obtain code-required R values or superinsulation levels if thickness is restricted, unless hybrid walls/ceiling installations are done (foam + cellulose). The most common remark I have seen is to check with the local AHJ to see what he will accept.
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mason
Posted: Sep 24, 2007 10:40 AM
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Small scale tests may be limited to 4 or 5 inches, but full scale room corner testing can be performed for fire exposure. In the case of R value, the ICC Evaluation Services is determining a change to the acceptance criteria for sprayfoam that would allow foam tested at 3.5 to 5 inches to determine values that can be used to extrapolate greater thickness. I;ve found that most building code officials will allow greater thickness when presented with credible data that can estimate insulation values greater than 4 inches. |
