Three years ago we bought some sheep wool insulation from Oregon Shepherd. The product was actually made in New Zealand, and a couple local farmers had imported a shipping container full of it and stored it in their barn. At the time we were wildly optimistic that we would soon be insulating, so we bought a bale to give it a try. Each 5 foot cube bale contained two vacuum sealed bags full of wool batts. Each batt was 4 foot long, and designed for stapled installation into 2×6 framed construction on 16 inch centers. The particular product we bought is no longer available locally, although Oregon Shepherd is now selling blown-in insulation made from U.S. sourced wool.
As an insulation product, wool has significant advantages. It is about R3.3 per inch, putting it in the same class as fiberglass, but without the associated itchiness, toxic binders, or hazardous dust. It is naturally fire resistant, insect resistant, sound dampening, and moisture buffering. Finally, wool is a renewable resource with far lower embodied energy costs than fiberglass, foam, or rock wool. The only real disadvantage is price–even the scraps used in insulation are labor-intensive to produce.
From an installer’s perspective, sheep wool insulation is wonderful compared to traditional fiberglass or rock wool insulation. Rock wool is the worst to handle and I always suit up in coveralls and safety glasses before I touch it. Despite those precautions, I feel itchy even after a shower. The new improved fiberglass insulation I’ve handled causes a tiny bit of itching but really isn’t bad. Sheep wool insulation is the only one I’ve installed in my pajamas and tank tops. There’s no itching! I just wish it was a little easier to cut.
So far, we are only using the wool insulation in the upstairs end walls. The inner layer of each end wall was framed in 2x3s so we can pull each batt in half to cover twice as much area. (Six inch thick sheep wool batts evenly tear into two three inch thick batts.) During the 3 years since we bought the wool bale, Lee forgot that it was intended for 16 on center, and he had the walls framed at 24 on center. This meant we had to cut each batt in half length wise and install them sideways. Lee used sheep shears to cut the bats in half.
I found the sheep shears hard to use, so I ended up using kitchen shears for trimming ends that were too long.
Once the wool bats were in place I tacked them up with a staple gun. The whole process was super easy, but time consuming.
The picture below is a finished end wall using the sheep wool insulation. Unlike most building products, it has a pleasant smell like a hay barn or a horse blanket.
We plan to use sheep wool insulation in a few other areas of the house, so we are going to have to track down another source for the batts.