Photograph of Moldy visible growing on a fiberglass insulation fiber  © Daniel FriedmanPolyurethane & Urethane Foam Insulation Outgassing & Properties

  • URETHANE FOAM Deterioration, Outgassing - CONTENTS: Urethane / Polyurethane building insulation outgassing. R-Value deterioration of polyurethane insulation products - stabilization point. Properties of urethane foam spray insulation products. Photo guide to identification of different building insulation materials
  • POST a QUESTION or READ FAQs about polyurethane and urethane foam outgassing

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This article discusses polyurethane foam insulation outgassing, the initial degradation in the R-value of foam insulation, and other properties.

Our photo (page top) shows icynene foam insulation that oozed into an attic space after being blown onto the building gable-end wall.

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Rate of Outgassing of Foam Insulation; relationship between thermal performance of foam insulation and time degradation

The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Polyurethane Foam R-Value Loss Mechanisms


Thank you for an excellent article on building insulation materials (Solar Age, "Building it Right", 11/83, also see our complete guide to insulation at INSULATION INSPECTION & IMPROVEMENT). Of all the areas in the field of energy-efficient materials and construction, none is so fraught with misinformation as insulation.

After many inquiries to manufacturers and extruders of rigid foam insulation products I have been unable to find accurate information as to the rate of outgassing in foam building insulation, or the relationship between thermal performance of foam insulation and time. Have you found any better information than I have? -- Michael Luttrell, Napa CA


Polyurethane foams lose R-value by two mechanisms: air infiltrating the foam and fluorocarbon gas diffusing out of the foam insulation.

Immediately after manufacture, polyurethane foam increases in conductivity quite rapidly. The rate of increase in foam insulating board conductivity (which is equivalent to a loss in the foam insulating board's R-value) ultimately stabilizes at a plateau level, which can remain unchanged after more than 10 years.

Since most of the change in foam insulating board R-value occurs in the first two to two-and-a-half years, manufacturers of residential foam insulating products are required to publish a two-year aged R-value.

The rate and degree of R-value drift in foam insulating board depends on many factors such as foam cell size, closed cell foam content, foam board material thickness, and foam board density.

The main factors, though, are the permeance of the foam board facing and how well it is bonded to the foam itself. Metal foam insulating board facings bonded to the wet foam at the time of manufacture (generally aluminum foil) appear to yield the highest R-values.

Through extensive testing at independent laboratories, Celotex Corp. has established that its foil-faced Thermax™ foam board insulation remains stable at about R-7.2 per inch at 75 degF mean temperature for at least five years of aging.

In its bulletin U108, the Urethane Division of the Society of the Plastics Industry lists the stabilized R-value for unfaced foam insulating board or those with gas-permeable facings at R5.6 to R 6.2 per inch of thickness. Consult with the manufacturers for information on specific foam insulating board products.

More Details about Polyurethane, Urethane, and Icynene Foam Insulation Products

Foam insulation sprayed in a crawl space - this is not mold - Daniel Friedman 04-11-01

From our detailed article at ICYNENE FOAM SPRAY INSULATION:

Icynene® foam insulation (and similar products) is a spray-in-place, injected through openings, or pour-in expanding-foam insulation product. Other water borne foam spray insulation products, including some latex-foams, are available.

For more about crawl space insulation, see CRAWL SPACE INSULATION RETROFIT.

The link to the original Q&A article in PDF form immediately below is preceded by an expanded/updated online version of this article.


Continue reading at FOAM SPRAY INSULATION TYPES or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.



See UREA FORMALDEHYDE FOAM INSULATION, UFFI for an example of an earlier set of problems with UFFI.

Suggested citation for this web page

URETHANE FOAM at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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