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INSULATION INSPECTION & IMPROVEMENT
ACOUSTICAL SEALANT CHOICES
AIR LEAK MINIMIZATION
ASBESTOS IDENTIFICATION IN BUILDINGS
BASEMENT CEILING VAPOR BARRIER
BASEMENT HEAT LOSS
BUCKLED FOUNDATIONS due to INSULATION?
CATHEDRAL CEILING INSULATION
CATHEDRAL CEILING VENTILATION
CEILINGS, DROP or SUSPENDED PANEL
DEW POINT TABLE - CONDENSATION POINT
DUCT INSULATION, ASBESTOS PAPER
FIBERGLASS PARTICLE CONTAMINATION
Fiberboard Insulation Sheathing Mold
FIBERGLASS INSULATION MOLD
FIREPROOFING ASBESTOS SPRAY-ON
FRAMING DETAILS for BETTER INSULATION
FRAMING DETAILS for DOUBLE WALL HOUSES
FRAMING METAL STUD PERFORMANCE
FREEZE-PROOF A BUILDING
HEAT LOSS in BUILDINGS
HEAT LOSS PREVENTION PRIORITIES
HEAT LOSS R U & K VALUE CALCULATION
HOUSEWRAP AIR & VAPOR BARRIERS
HOUSE DOCTOR, how-to be
HUMIDITY LEVEL TARGET
ICE DAM PREVENTION
INSULATION AIR & HEAT LEAKS
INDOOR AIR QUALITY & HOUSE TIGHTNESS
INSULATION FACT SHEET- DOE
INSULATION INSPECTION & IMPROVEMENT
INSULATION R-Values & Properties
LEED GREEN BUILDING CERTIFICATION
LOG HOME ENERGY EFFICIENCY
MOLD in FOAM INSULATION, RESISTANCE
MOISTURE CONTROL in BUILDINGS
NOISE / SOUND DIAGNOSIS & CURE
RIGID FOAM USE INDOORS
SHEATHING, FOIL FACED - VENTS
SLAB INSULATION, PASSIVE SOLAR
STAINS on & in BUILDINGS, CAUSES & CURES
STRAW BALE CONSTRUCTION
STUCCO WALL METHODS & INSTALLATION
STUCCO OVER FOAM INSULATION
SWEATING (CONDENSATION) on PIPES, TANKS
Thermal Expansion Cracking of Brick
THERMAL IMAGING, THERMOGRAPHY
THERMAL MASS in BUILDINGS
THERMAL TRACKING Indicates Heat Loss
TRUSS UPLIFT, ROOF
VAPOR BARRIERS & CONDENSATION in BUILDINGS
VENTILATION in BUILDINGS
WALL CONSTRUCTION BARRIER vs CAVITY
WIND WASHING INSULATION At EAVES
WINTERIZE A BUILDING
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
Readers should see INSULATION INSPECTION & IMPROVEMENT and Icynene Foam Spray Insulation. If you are having trouble determining what type of foam insulation product has been installed in a building, see How to Make a Sure Distinction Among UFFI, Icynene, and Latex Foam Insulations for more detail on the identification of these products in the field. And we discuss the reduced risk of mold where icynene is in crawl spaces at Mold risk in Icynene Foam Insulation. See UREA FORMALDEHYDE FOAM INSULATION, UFFI for an example of an earlier set of problems with UFFI.
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
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.
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Technical Reviewers & References
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