Those of us attending the latest Boston Dbug meeting hosted by Neil Blanchard learned about his interest in using blown-in sheep's wool insulation for his upcoming roof insulation project at his home. As a residential architect myself who frequently wrestles with selecting the appropriate type of insulation for any given project, I was intrigued. A preliminary on-line investigation into the subject reveals that this green alternative offers a number of attractive benefits not the least of which is a higher R-value (~4.1) than dense-packed blown cellulose (~3. and a high resilience against moisture in that it can absorb water vapor and dry out again without losing efficacy. It is also (obviously) an all natural type of insulation with no known harmful chemicals (like formaldehyde), or any skin or respiratory irritants. It is also considered "green" in that wool is somewhat surprisingly now largely considered a waste product because the fabric industry has far less demand for it now than in the past, therefore putting all surplus wool to good use is beneficial. However, despite these attributes, the cost of wool insulation is about double that of cellulose. One reason for the high cost I suspect is that I was only able to find 4 companies that sell the product in the U.S., three of whom import their wool either from New Zealand or the U.K. A deeper dive would probably uncover a few more, but here are the four: Havelock, Black Mountain, Wool Life Industrial Products and Oregon Shepard. I believe only Oregon Shepard uses sheep's wool raised in USA. All of these companies have websites extolling the virtues of wool insulation but they don't offer much in the way of scientific testing to back up the claims, though maybe I didn't dig deeply enough. Still, it looks like a nice low-carbon alternative and hopefully we'll see it becoming more prevalent in the years ahead. Neil, please add any other information you've gathered on this topic and also let us know what you ultimately select to install at your roof.
Thanks Mark! I first heard about blown in wool at ABX two years ago. There are also wool batts, and I don't know details about them.
https://havelockwool.com/ Their processing is done in Reno NV, and their wool comes from New Zealand. They use Romney sheep wool, which coarser than some other wool. They make both blown in and batt.
https://www.blackmountaininsulation.com/ Their address is in the UK.
https://naturalwool-insulation.com/ This company is also located in the UK.
http://oregonshepherd.com/ They make both blown in and batt. Their blown in product is reclaimed wool textiles, so it is random multicolored.