The long term mechanical and thermal stability of an insulation is an important consideration that is often overlooked.  The thermal performance of some conventional insulations are drastically reduced over time due to sagging, settling, or off-gassing.  In addition, mechanical breakdown may occur when exposed to wet/dry or freeze/thaw cycling under adverse conditions.

Thermal Drift: Reduction in measured “R-Value” of an insulation as it ages.  This is directly related to a product’s chemical stability.  Primarily a concern with foam products containing CFC’s.

IMPACT:  Causes a reduction in the insulation’s “R-Value” over time as insulating gasses are released and replaced with air.

Physical Stability: The ability of an insulating material to maintain its shape, rigidity, and strength over time.

IMPACT:  Breaches in insulation due to physical degradation, settling, sagging, or installation shortcomings can result in significant heat loss from the building envelope, through thermal short circuiting and air leakage.