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Under the IECC can R-19 open cell spray foam installed at the roof deck be assumed to perform as R-38 insulation?

Txcodeguy43

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Joined
May 12, 2018
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Houston
Icynene is saying a commercial, stick-frame building with open cell spray foam installed 5.5" thick at the roof deck performs the same as R-38. Has anyone run across this? Their explanation goes on to say that the enhanced performance is determined by energy modeling they have performed on certain test buildings. If this is true, then is it simply a matter of having an energy modeling report done on the building in question? And does this mean it is beyond the scope of the Comcheck software? Thanks in advance.
 

TheCommish

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Sep 27, 2011
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Charlton Ma
how does spray foam that has an R-value of 3.5 per inch @ 5.5= 19.5?

Is the claim because they are covering the rafters or ceiling joists and creating a thermal break?
 

classicT

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Aug 2, 2017
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Washington State
What climate zone are you in?

Per IECC Table 402.1.1 (below), I do not believe that the IECC provides alternate R-value for insulation above roof deck or underside of rafters.

1601650203821.png
 

Paul Sweet

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Oct 17, 2009
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Richmond, VA
Which Icynene product? Icynene shows a range of R-values ranging from 3.7 up to 6.75 for their different products.
 

rogerpa

Silver Member
Joined
Nov 5, 2009
Messages
282
Icynene has made this claim for years. They're trying to claim that the reduced air infiltration gives the equivalent higher R-Value. They are in violation of federal law.
In climate zones 5A & 6A we have experienced "raining" in the attic due to moistue migrating through the open cell foam and condensing when it comes in contact with the cold underside of the roof sheathing.

CFR(Code of Federal Regualtions) https://www.ecfr.gov/cgi-bin/retrie...c97a7&ty=HTML&h=L&mc=true&n=pt16.1.460&r=PART

Title 16: Commercial Practices

PART 460—LABELING AND ADVERTISING OF HOME INSULATION

§460.5 R-value tests.

R-value measures resistance to heat flow. R-values given in labels, fact sheets, ads, or other promotional materials must be based on tests done under the methods listed in paragraphs (a) through (d) of this section.

(a) All types of insulation except reflective insulation must be tested with ASTM C177-13, “Standard Test Method for Steady-State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus;” ASTM C518-17, “Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus;” ASTM C1363-11, “Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus” or ASTM C1114-06, “Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Thin-Heater Apparatus.” The tests must be done at a mean temperature of 75 degrees Fahrenheit and with a temperature difference of 50 degrees Fahrenheit plus or minus 10 degrees Fahrenheit. The tests must be done on the insulation material alone (excluding any airspace). R-values (“thermal resistance”) based upon heat flux measurements according to ASTM C177-13 or ASTM C518-17 must be reported only in accordance with the requirements and restrictions of ASTM C1045-07, “Standard Practice for Calculating Thermal Transmission Properties Under Steady-State Conditions.”
 

tmurray

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Jun 10, 2011
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NB, Canada
Which Icynene product? Icynene shows a range of R-values ranging from 3.7 up to 6.75 for their different products.
Likely one of the 50s. The 200 is a closed cell.
 
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