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Norman McDonald Posted: Jul 18, 2008 02:39 PM	Closed Cell Thickness Standards? I am a South Carolina licensed Mechanical and General Contractor where state law requires: “(a) R-30 in ceilings, except for ceiling/roof combinations, which be at least R-19; (b) R-13 for exterior walls; and (d) R-19 for floors with crawl space.” When attempting to calculate “Heat Loads” [Based on R-19] for a new construction home where Closed Cell Foam was recently applied I observed that the depth of the new Foam measures randomly between .5” to 1.75” in the center area of the 16” on center roof deck rafters and floor joists above a 14’ high open-air garage area. The Foam Contractor was summoned who concurred with our findings, but countered that actual depth is not as important as over-all average while pointing out the Foam accumulation or build-up as high as 3.5” against the wooden perimeters for about 1” and sloping toward the center area, thus, resulting in a concave formation. All of the material I have researched indicates the “R Value” specifications of CC Foam ranges anywhere from R-5.6 (DOE) to R-7 (Manufacturers) per inch thickness while essentially agreeing that a 2.8” to 3” thickness is the universally accepted standard to achieve R-19. I have found nothing alluding to R Value computations via averaging. However, if the averaging method were used in this case, a 1.75” overall thickness would be derived, thus, providing a value of R-14, depending upon who’s specifications were employed. Please share any industry or workmanship standards regarding acceptable uniform thickness of CC Foam to achieve a desired “R Value".
Dan Beecher Posted: Jul 18, 2008 03:35 PM	If he said he was putting 3" or a R-19 in the roof deck, he should be +/- 1/4" of that mark for a REPUTABLE contractor. Sounds like he sold you on 3" put in what he did thinking now one would check it, now trying to song and dance his way out of it and take his profit to the bank. All the manufacturers have a little different aged R value. Ask him to see the tech data sheet on the brand he sprayed to get the aged R value.Sounds like he should be up there finishing the job to me.
D. Backes Posted: Jul 19, 2008 05:46 PM	He needs to come back and spray some more. For high density foam 1/4" +/- is acceptable. 1/2" of foam is worthless and asking for condensation problems.
philip mullins Posted: Jul 22, 2008 12:52 AM	seeing more and more of this lately. on a roof deck you can spray thin in the middle and thick along the joist. looking up at it you see the correct amount of joist exposed and it gives the illusion of depth. thats one way the "low-bidder" can still make money. only a half inch in the center is ridiculous, even by cut-throat standards! these guys tend to hide behind the "average" scenario when called on thier BS.
Norman McDonald Posted: Jul 30, 2008 04:32 PM	As a General Contractor who specifies R-19 to conform to local State Law (or 3" of closed cell foam to conform to USDOE guidelines) be reasonable in demanding 3" thickness at random sample points plus or minus .25" thickness before accepting the job and issuing payment for services rendered. Local Building Inspectors say they are not trained in this new technology and rely on industry standards or what Foam Contractors tell them, but there doesn't seem to be any universal standards other than the thoughtful replies I have received here. Finally, does anyone know of a contractor who can meet these specifications in Charleston, SC? Thank you, Norman

Author

Comments

Norman McDonald

Posted: Jul 18, 2008 02:39 PM

Closed Cell Thickness Standards?

I am a South Carolina licensed Mechanical and General Contractor where state law requires: “(a) R-30 in ceilings, except for ceiling/roof combinations, which be at least R-19; (b) R-13 for exterior walls; and (d) R-19 for floors with crawl space.”

When attempting to calculate “Heat Loads” [Based on R-19] for a new construction home where Closed Cell Foam was recently applied I observed that the depth of the new Foam measures randomly between .5” to 1.75” in the center area of the 16” on center roof deck rafters and floor joists above a 14’ high open-air garage area.

The Foam Contractor was summoned who concurred with our findings, but countered that actual depth is not as important as over-all average while pointing out the Foam accumulation or build-up as high as 3.5” against the wooden perimeters for about 1” and sloping toward the center area, thus, resulting in a concave formation.

All of the material I have researched indicates the “R Value” specifications of CC Foam ranges anywhere from R-5.6 (DOE) to R-7 (Manufacturers) per inch thickness while essentially agreeing that a 2.8” to 3” thickness is the universally accepted standard to achieve R-19.

I have found nothing alluding to R Value computations via averaging. However, if the averaging method were used in this case, a 1.75” overall thickness would be derived, thus, providing a value of R-14, depending upon who’s specifications were employed.

Please share any industry or workmanship standards regarding acceptable uniform thickness of CC Foam to achieve a desired “R Value".

Dan Beecher

Posted: Jul 18, 2008 03:35 PM

If he said he was putting 3" or a R-19 in the roof deck, he should be +/- 1/4" of that mark for a REPUTABLE contractor. Sounds like he sold you on 3" put in what he did thinking now one would check it, now trying to song and dance his way out of it and take his profit to the bank. All the manufacturers have a little different aged R value. Ask him to see the tech data sheet on the brand he sprayed to get the aged R value.Sounds like he should be up there finishing the job to me.

D. Backes

Posted: Jul 19, 2008 05:46 PM

He needs to come back and spray some more. For high density foam 1/4" +/- is acceptable. 1/2" of foam is worthless and asking for condensation problems.

philip mullins

Posted: Jul 22, 2008 12:52 AM

seeing more and more of this lately. on a roof deck you can spray thin in the middle and thick along the joist. looking up at it you see the correct amount of joist exposed and it gives the illusion of depth. thats one way the "low-bidder" can still make money. only a half inch in the center is ridiculous, even by cut-throat standards! these guys tend to hide behind the "average" scenario when called on thier BS.

Norman McDonald

Posted: Jul 30, 2008 04:32 PM

As a General Contractor who specifies R-19 to conform to local State Law (or 3" of closed cell foam to conform to USDOE guidelines) be reasonable in demanding 3" thickness at random sample points plus or minus .25" thickness before accepting the job and issuing payment for services rendered.

Local Building Inspectors say they are not trained in this new technology and rely on industry standards or what Foam Contractors tell them, but there doesn't seem to be any universal standards other than the thoughtful replies I have received here.

Finally, does anyone know of a contractor who can meet these specifications in Charleston, SC?

Thank you,

Norman

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