Why Wool Works

There are many unique qualities of the wool fiber that make it a high-performing insulation – moisture management, air filtration, sound absorption, fire resistance. One aspect that can be difficult to appreciate is how wool naturally expands over time. When we ship Havelock Wool the bags are compressed to reduce dimension and therefore shipping cost. Upon arrival at the build site, the wool insulation can appear to be less than what you need. But here is where the expansion properties of wool reveal themselves….

Check out this video from Lucas Johnson (@science_to_save_the_world) at 475 High Performance Building Supply which shows Havelock Wool in action.

Why is this an important quality of Havelock Wool insulation? What does it reveal about its dynamic qualities?

A key job of any insulation is to regulate temperature. This is measured by thermal conductivity (heat loss through solid materials) and assigned an R-Value. Insulation needs to be in contact with those materials to help them reduce their conductive properties. Less contact means more conductive loss which means the actual R-Value isn’t what you paid for. Havelock Wool has a natural loft that allows it to properly fill a wall cavity upon installation. Importantly, the natural loft of wool persists over time. Lucas’s video above shows just that.

We’d be remiss if we didn’t also mention moisture management, another dynamic quality of wool. As we’ve written before, moisture inevitably finds its way into walls and how insulation responds is crucial. An insulation fiber of lesser integrity eg fiberglass and cellulose can slump when it absorbs moisture which causes the insulation to lose contact with the wall cavity. All of a sudden, the actual R-Value is way less than stated, you’ve got wet insulation stuck in your wall and this slumping never reverses. Conversely, wool absorbs and desorbs moisture so it maintains its loft and R-Value across time. There is no slumping, no wet insulation stuck in your wall and because wool is a keratin – no mold.

As ever, thanks for reading along. Our goal at Havelock Wool is to provide transparency around insulation options available to consumers. Clearly, we are biased to wool and we hope you agree. But if not, we are happy to at least provide more perspective to the important conversation around healthy, sustainable building.