The pros and cons of sheep wool insulation for homes

As more people begin to factor indoor air quality and health of occupants into home building and renovation plans, natural insulation materials are gaining traction in the market. Sheep wool insulation is one such example. Can you really keep a home warm with sheep wool insulation? Well, it seems to work well for sheep, except of course the ones that got a recent buzz cut.

Many natural insulation options for homes are making their way into homes in recent years, as a high-performance alternative to conventional insulation materials like fiberglass, and the potential health impacts of spray foam insulation. Derived from natural sheep wool, this material offers unique benefits, but like most things in life you need to read the fine print because it comes with certain drawbacks. Here we’re going to look at the pros and cons.

The pros of sheep wool insulation

1. Healthy indoor air quality

Sheep wool is an entirely natural product and does not emit harmful volatile organic compounds (VOCs) commonly found in synthetic insulation materials. So for those with chemical sensitivities choosing natural sheep's wool insulation can offer a much safer environment.

2. Moisture durability and breathability

One of wool’s standout properties is its ability to manage moisture. Sheep wool can absorb up to 35% of its weight in water without compromising its insulating properties. This hygroscopic nature helps regulate indoor humidity levels and reduces the risk of mold and mildew growth, contributing to a healthier living environment.

3. Thermal performance (R-value)

Sheep wool insulation has an R-value of approximately R-3.5 to R-4.0 per inch, comparable to conventional fiberglass insulation. This makes it effective at reducing heat loss and maintaining comfortable indoor temperatures. Wool’s natural crimp traps air efficiently, enhancing its insulating performance.

4. Sustainability and environmental impact

As a renewable resource, sheep wool is biodegradable and has a lower environmental impact compared to petrochemical-based insulation materials. Its production process typically requires less energy, and its end-of-life disposal can be a compost pile and so it does not contribute to landfill waste.

5. Fire resistance

Sheep wool contains a natural substance called lanolin, which gives it impressive fire-resistant properties. It has a high ignition temperature of about 1,100°F (593°C) and does not emit toxic fumes when exposed to flames, making it a safer choice for homes.

6. Easy installation

Sheep wool insulation is soft and pliable, making it easier to handle and install compared to fiberglass, which can also irritate the skin and respiratory system. 

7. Safety for installers 

For anyone that has spent time installing any type of toxic material, you would know the additional hassle of wearing safety equipment such as respirators and gloves, or, the stress of being exposed to such materials without the appropriate PPE. Not worrying about your health, or trying to see through fogged up safety glasses from a respirator is a huge improvement in qualilty of life for installers, and it also speeds you up. 

The downsides of sheep wool insulation

1. Higher cost

One of the most significant drawbacks of sheep wool insulation is its cost. On average, it is two to three times more expensive than fiberglass or mineral wool insulation. While its durability and performance may justify the expense in some cases, budget-conscious homeowners might find it prohibitive. 

2. Product availability

Sheep wool insulation is not as widely available as conventional insulation materials. Depending on your location, sourcing the product might involve higher shipping costs or longer lead times, which can delay construction schedules.

3. Potential for odors

Concerns about odors in sheep wool insulation are often raised, especially in humid climates. If not properly treated and processed, residual lanolin in the wool have the potential to offer you a slight ‘barnyard’ kind of smell to you home it is said.

However, most manufacturers treat their wool with natural and safe odor-neutralizing agents to mitigate this issue. Choosing high-quality products from reputable suppliers significantly reduces the likelihood of unexpected aromas. Find sheep wool insulation suppliers here in the ecohome product directory

4. Pest concerns

Untreated sheep wool may attract pests like moths and rodents. But again, you might want to find manufacturers that treat the wool with borates or other natural pest repellents to address this issue.

5. Compression over time

Sheep wool insulation is not as rigid as some synthetic materials, and there is a potential for compression over time. This can slightly reduce its thermal performance, especially in areas where it is subject to pressure or vibration. Proper installation techniques, such as avoiding over-packing, can help mitigate this concern.

Sheeps wool insulation in Tiny Homes and Van conversions

Sheep wool insulation is an excellent choice for tiny homes and van conversions due to its high performance and natural properties. The compact and efficient nature of these spaces means that the benefits of sheep wool insulation, such as its ability to regulate temperature and moisture, are even more impactful. Sheep wool is hygroscopic, meaning it can absorb and release moisture, helping to maintain a balanced, comfortable interior environment. This is particularly important in small, confined spaces where excess moisture can lead to issues like mold or condensation. Additionally, wool’s natural insulating properties help maintain warmth in winter and coolness in summer, providing year-round comfort despite the limited space.

Another advantage of sheep wool insulation in tiny homes and van conversions is its positive impact on indoor air quality. Unlike synthetic insulations, sheep wool does not emit harmful chemicals or off-gases, which is a significant consideration in smaller, more enclosed living spaces. The wool is also naturally fire retardant, adding an extra layer of safety. For tiny home or van builders, the relatively small area being insulated makes the cost difference between sheep wool and other materials more marginal. In this context, the higher initial investment in wool insulation is balanced out by its durability, energy efficiency, and long-term benefits, making it a wise choice for those seeking sustainable and healthy living environments.

Our conclusions on sheep wool insulation

We see this as an attractive option for homeowners that prioritize sustainability, indoor air quality and moisture management. Its natural fire resistance, ease of installation, and comparable R-value to conventional insulation make it a strong contender for eco-conscious building projects.

Aside from the cost and limited availability, its really the potential for odor that gives us pause for thought. That point is not intended to be overly dissuasive, but it’s a consideration. You could look at it as a motivation to really nail down the wall assembly design and build quality. With a high performance airtight wall assembly it sounds to us like its less of an issue.

When considering sheep wool insulation, it’s crucial to source the material from reputable suppliers and weigh the long-term benefits against the upfront investment. For those committed to sustainable construction and creating healthier indoor environments, sheep wool insulation offers a compelling and environmentally friendly solution.

As this is about as much of a fringe building product as you’ll find, we’d love to hear first hand experience from anyone that has tried it, so if that’s you please drop us your feedback in the comments section below!