"OUT-GASSING" and "AGED R-VALUE"

OUTGASSING – Occurs when fumes or gasses escape from an object over time. All things outgas to some degree, wood, carpet, cabinets, fabrics, paint, even people.

AGED R-VALUE – The R-value of certain materials will be reduced over time due to a process known as outgassing. Because the long-term R-value of the material is lower than the R-value when the material was new, the term "Aged R-value" is used to represent the extended R-value.

Since out-gassing and aged R-value are related, they will be discussed in the same review.

OUTGASSING IN EXPOSED URETHANE FOAM

Urethane foam has a higher R-value per inch than other insulating materials, primarily due to two conditions. Firstly, the cell structure of the foam is denser than in most materials and secondly, these cells or ‘air pockets’ are filled with an inert gas that has a higher R-value than oxygen. Each urethane foam formulation has different cell and gas properties. This bulletin will address a general type of ridged-structural foam similar to that used by SIP manufactures.

Foam used by SIP manufactures is a closed cell, ridged, structural foam. This foam might have an R-value of 6.0 contributed to by the higher density cell structure and an R-value of 1.0 contributed by the inert gas trapped in each cell. The combined R-value for this product would be an R-7 per inch.

The gas trapped in each cell is at a higher pressure than the surrounding atmosphere. If the outer surface of the foam is exposed directly to atmospheric pressure, the pressure differential between the outer-layer of cells and the atmosphere will cause, over time, the inert gas to escape. The escaped gas will have the effect of lowering the R-value of that individual cell. Once the outer cells are at a lower pressure, there will be a pressure differential between the outermost layer of cells and the second layer of cells. Gases in the second layer of cells will then migrate to the outer layer of cells. This process will continue until equilibrium is reached within the cell structure of the foam sample. It should be noted that there is some resistance to gas migration from cell to cell, so the innermost cell of a foam sample will stabilize at a higher pressure than the outer layer of cells, so not all of the gas will escape.

The actual reduction of R-value and the amount of gases that would escape depend on the exact formulation of the foam and the thickness of the sample. The thicker the sample the less effect out-gassing will have on the overall R-value.

OUTGASSING IN URETHANE FOAM SIP’s

Out-gassing in urethane foam occurs when the surface is exposed to atmospheric pressure. SIP’s, by their nature, cover the large surfaces of the foam core with material or "skins", virtually sealing the surface from the effects of the pressure differential. The result is that SIP’s do not experience any measurable amounts of out-gassing or loss of R-value from the foam.

Several tests and reports have confirmed this analysis. 1) Tests were conducted by Lars-Erik Larsson, Professor, Division of Building Technology, Goteborg, Sweden, measuring the effect of "skins" on urethane foam panels. Their study concluded that foam panels with a skin, measured no decrease in R-value over a 7 year test period. 2) A second test was conducted using plasterboard and chipboard as skins, and found no decrease of R-value in a 3-year test. 3) In addition a test house that was built in 1965 with semi-hard wood fiber skins, was tested after 11 years and found no loss of R-value. 4) A Canadian committee with the Society of the Plastics Industry pointed out that where urethane was protected with a truly impermeable membrane it would retain most of its original R-value. 5) A door was cut into an eight-year-old very humid pump house built by Alchem of Anchorage, Alaska. The removed material was measured to have an R-value of 6.94. The Alchem study indicates that wood-faced panels may indeed provide enough resistance to retard the migration of air into and gas out of the foam cells within urethane.

CONCLUSION

No measurable outgassing or loss of R-value will occur when wood skins protect urethane foam.

KC Panels actual R-value, tested by UL, provides an R-7.69 per inch. In an effort to not overstate the R-value or to allow for any variance that may occur in the manufacturing process, KC Panels are advertised as an R-7.0 per inch. There should be no reason to believe that KC Panels would not perform at this level throughout the life of the building.