Insulating Homes With Sheep Wool

What Is Sheep's Wool Insulation?

Sheep's wool insulation is natural insulation made from real sheep’s wool. Sheep in Iceland can withstand brutally cold winters, thanks to their wool’s unique properties. It’s crimped and folded, forming millions of tiny air pockets that create a thermal barrier against extreme hot or extreme cold. Sheep’s wool insulation manufacturers build on that principle to develop batts or insulation rolls from individual wool fibers. Most industrial wool insulation is held together with polyester adhesive, but you can find 100% natural products.

Sheep’s wool insulation is often confused with the VERY different mineral wool insulation, made from molten basalt or iron ore fibers.

Are Sheep Harmed During Sheering for Sheep’s Wool Insulation?

The thought of a sheep being harmed to help build your home is an absolute no-go. That’s why you want to choose a manufacturer that takes Animal Welfare practices very seriously. Like the standard wool exporter, New Zealand, most nations ban a harmful practice called “mulesing.” Responsible sheep farming is more than possible and pretty standard nowadays, so don’t be afraid to do careful research on where your manufacturer gets their wool.

What Are The Advantages Of Using Sheep's Wool Insulation?

Sheep's wool insulation is that this natural material can also naturally regulate humidity levels in the home. If you ever touch a sheep outside during a rainstorm, you will probably be amazed that fine that their wool will feel dry to the touch. The unique consistency of sheep wool allows this natural product to absorb around 33 percent of its weight in moisture without ever losing its insulating ability. Whereas exposure to water or humidity can damage fiberglass and other common types of loose-fill insulation, this isn't a concern with sheep wool.

The hygroscopic nature of sheep wool insulation can also help purify your indoor air, especially for homes that suffer from excess moisture or humidity. Besides capturing excess humidity, sheep wool can also amazingly pull and store harmful VOCs such as nitrogen dioxide and formaldehyde that compromise your indoor air quality. This air-cleansing ability is possible because of the natural proteins in sheep wool that create a chemisorption process.

What Are The Disadvantages Of Using Sheep's Wool Insulation?

Sheep wool offers several sustainability benefits that we have outlined above. On the downside, however, sheep wool batts can be more expensive than other insulation options. Raw sheep wool can be sourced relatively inexpensively. Because many building experts still consider sheep wool insulation to be a sustainable novelty item, manufacturing does drive up the cost. As more homeowners discover the benefits of this natural insulation option, prices should continue to drop.

In terms of overall thermal property and insulation capacity, sheep wool insulation products are not the best on the market. According to the Healthy House Institute, "sheep wool insulation has an R-value of approximately 3.5 to 3.8 per inch of material thickness, 0.3 to 0.6 points higher than fiberglass, cellulose, or mineral wool." For comparison's sake, vacuum insulated panels can have an R-Value of R-45 per inch, while polyurethane and phenolic foam insulations usually obtain R-7 per inch. For homeowners in cold climates, wool insulation batts can still be used. However, you will most likely need customized wall studs to achieve optimum insulation for the best thermal performance.

Is Sheep's Wool Insulation Sustainable?

In terms of its manufacturing process, sheep’s wool boasts one of the least energy-intensive processes among insulation products. It’s a natural material that goes through limited processing outside of spinning, bonding, and some chemical treatments to make it resistant to critters. Some manufacturers claim that wool’s embodied energy is less than half of cellulose insulation. Studies suggest that "sheep wool requires less than 15% of the energy used to manufacture glass wool."

Besides being a 100 percent natural product, sustainably and regeneratively-grazed sheep on healthy pastures can capture carbon dioxide from the atmosphere and sequester it in the soil. Increased demand for sheep wool insulation can stimulate local economies and give local farmers a new product from the livestock they raise.

Since sheep’s wool insulation is still relatively new to North America, the material might have to travel long distances to reach home. This adds to the embodied energy of sheep’s wool. Be mindful of where the raw material is coming from and your distance from the manufacturer.

Is Sheep's Wool A Good Insulator?

Besides coming from a regenerative source, sheep wool is also an excellent insulator. The millions of tiny air pockets can trap air, thus creating a thermal barrier from outside temperatures. When combined with different polymers or glues to hold the fibers together, sheep wool insulation can be installed in almost any stud-built home. It is also helpful for attic and loft insulation.

What Is the R-value of Sheep's Wool Insulation?

The R-value of sheep's wool insulation ranges between 3.5 and 3.8 per inch. On average, sheep's wool insulation is approximately 0.3 to 0.6 points higher than alternative insulation options such as mineral wool, cellulose, and fiberglass. The additional R-value is primarily due to sheep wool insulation's crimped nature, which traps air in millions of tiny bubbles.

Is Sheep's Wool Insulation Mold and Mildew Resistant?

Sheep's wool insulation is naturally resistant to mold and mildew due to its natural ability to wick moisture. While other insulation types may be susceptible to moisture build-up leading to mold and mildew, sheep's wool fibers allow moisture to pass through without retaining it.

Does Sheep's Wool Insulation Attract Insects or Moths?

Untreated sheep's wool can attract moths and other insects. Most sheep's wool insulation is washed and treated with non-toxic ingredients that are often odorless and contain no volatile solvents.

Is Sheep's Wool Insulation Resistant To Rodents?

The type of insulation you use does not necessarily increase the likelihood of attracting rodents. Rodents search for dry and cool areas to escape from the heat, wetness, or cold. A well-sealed building envelope is your best line of defense against rodents.

Does Sheep's Wool Insulation Smell?

Sheep's wool insulation may emit a faint smell for up to three days, but it is not harmful nor unpleasant. In comparison, many homeowners who have used sheep's wool insulation compare it to a new carpet smell.

Is Sheep's Wool Insulation Flammable?

Sheep's wool has naturally high nitrogen and water content, so it needs high oxygen levels to burn. When wool heats up and combusts, its cell membrane structure swells, forming an insulating layer that prevents flame spread. Most sheep’s wool insulation products meet Class A building code for flame spread and smoke development, putting it at the front of the pack along with cellulose, mineral wool, and fiberglass insulation.

How Long Does Sheep's Wool Insulation Last?

Using a natural alternative for insulation should also be a long-term solution. Having to replace your insulation every couple of years would be a considerable expense that most homeowners would not be able to make. Fortunately, sheep wool insulation, when properly installed, can last a lifetime. Its ability to naturally absorb and exude moisture and water vapor can be advantageous, especially in wet climates. Even at the end of its lifetime, sheep wool insulation will be 100 percent biodegradable.