NAIMA/Insulation Institute frequently fields questions regarding various performance aspects of fiberglass and mineral wool insulation. One of the most common questions we receive is, “what is the typical lifespan of fiberglass and mineral wool insulation?” Other questions come up regarding settling and loose fill insulation. There are many misconceptions about fiberglass and mineral wool insulation products' performance and longevity, so pointing out research that can help dispel myths is often necessary.

Two Studies of Note

NAIMA has sponsored research on fiberglass and mineral wool insulation products' performance in two separate studies. Those tests showed fiberglass and mineral wool do not experience a reduction in thermal performance over time, nor is settling an issue. The following is a brief description of those research projects and their results:

Settling of Fiberglass and Mineral Wool in Walls:

 A study looked at the effect of vibrations from a door being firmly closed on the possible settling of insulation in walls. A test wall was built and insulated with fiberglass batts, fiberglass dense-pack, and mineral wool batts and subjected to the vibration of a door being closed 65,800 times. The impact from the door did not result in any measurable settling of the insulation materials and, thus, would not reduce thermal performance.  Other studies confirm that settling is not an issue with fiberglass and mineral wool.

Aged Insulation Evaluation:

The second project looked at actual aged samples of fiberglass insulation gathered in homes. This project showed that the average of 8 fiberglass batts between 30 and 40 years old perform at 95.5. percent of the labeled R-value, and the range was between 75 and 109 percent of the labeled R-value with only one sample less than 90 percent.

Other groups, including the International Association Home Inspectors and the Home Innovation Research Labs, estimate fiberglass insulation’s life at 100+ years.

Why It Matters

Product performance aspects like settling and lifespan should be considered when evaluating any home insulation products. Often, performance aspects of fiberglass and mineral wool are misrepresented or distorted. Studies that demonstrate the performance of insulation products help builders and homeowners make informed insulation choices.