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JohnPeters Posted: Oct 27, 2008 08:03 AM	Law of Diminishing Returns - CLosed Cell Foam Mason, Do you have any studies conducted on the R-30 to R-38 threshold point where the added depth of closed cell over 4.5 - 5.5" is unnecessary? I have a customer that wants to install 9" of CC and I need ammunition to convince them the 9" is overkill. I know what your thinking - I should be happy that I am bidding on a job that is calling out 9" of CC. But, I cannot perform this installation knowing that the end user is going to completely benefit from the this excessive amount of foam. Mr. Honest.
mason Posted: Oct 27, 2008 08:21 AM	A few years ago, Roger Morrison of NCFI made a presentation at the annual Sprayfoam conference about this subject. I believe you can obtain a copy of the presentation from SPFA. Contact Rick Duncan with SPFA at 800-523-6154 for details. The paper may also be available online at sprayfoam.org. Plus, you can perform your own calculations. Remember, sprayfoam will provide close to 100% performance in varying climatic conditions based on research conducted at ATI. Just by doing the math, it can be determined that more than 5 inches of SPF contributes very little to stopping additional heat transfer.
JohnPeters Posted: Oct 27, 2008 08:29 AM	Perform my own calculations? Are you referring to RESNET or RESCHECK? I am very interested in how I can prove this myself...
mason Posted: Oct 27, 2008 03:25 PM	John, There are a number of calculators out there. Here is one from ORNL http://www.ornl.gov/sci/roofs+walls/insulation/ins_16.html This one will not provide the great results from SPF. But, if you use a 20 to 30% reduction in R value for the added benefit of SPF for its air sealing capability, you will get a pretty good SPFA has a trial roofing calculator that should be available to members soon. I have a beta version of it to help test drive it. It takes not only air infiltration, but thermal bridging and moisture content into its calculations.

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JohnPeters

Posted: Oct 27, 2008 08:03 AM

Law of Diminishing Returns - CLosed Cell Foam

Mason,

Do you have any studies conducted on the R-30 to R-38 threshold point where the added depth of closed cell over 4.5 - 5.5" is unnecessary?

I have a customer that wants to install 9" of CC and I need ammunition to convince them the 9" is overkill.

I know what your thinking - I should be happy that I am bidding on a job that is calling out 9" of CC. But, I cannot perform this installation knowing that the end user is going to completely benefit from the this excessive amount of foam.

Mr. Honest.

mason

Posted: Oct 27, 2008 08:21 AM

A few years ago, Roger Morrison of NCFI made a presentation at the annual Sprayfoam conference about this subject. I believe you can obtain a copy of the presentation from SPFA. Contact Rick Duncan with SPFA at 800-523-6154 for details.

The paper may also be available online at sprayfoam.org.

Plus, you can perform your own calculations. Remember, sprayfoam will provide close to 100% performance in varying climatic conditions based on research conducted at ATI. Just by doing the math, it can be determined that more than 5 inches of SPF contributes very little to stopping additional heat transfer.

JohnPeters

Posted: Oct 27, 2008 08:29 AM

Perform my own calculations?

Are you referring to RESNET or RESCHECK?

I am very interested in how I can prove this myself...

mason

Posted: Oct 27, 2008 03:25 PM

John,

There are a number of calculators out there. Here is one from ORNL http://www.ornl.gov/sci/roofs+walls/insulation/ins_16.html

This one will not provide the great results from SPF. But, if you use a 20 to 30% reduction in R value for the added benefit of SPF for its air sealing capability, you will get a pretty good

SPFA has a trial roofing calculator that should be available to members soon. I have a beta version of it to help test drive it. It takes not only air infiltration, but thermal bridging and moisture content into its calculations.

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