Understanding Wool Insulation: Benefits & Uses

Key Takeaways

• Wool insulation is natural, sustainable, and safe for indoor use.

• It provides excellent thermal and acoustic performance.

• It helps regulate indoor humidity and sequesters carbon

• It is mold, pests, and fire resistant.

• Ideal for eco-conscious homeowners and green builders.

• Products like Havelock Wool are available at Eco-Building Products.

Introduction

As energy efficiency and indoor air quality take center stage in home design, many homeowners and builders are turning to natural materials. Wool insulation, especially from trusted brands like Havelock Wool, offers a renewable, high-performing, and safe alternative to traditional fiberglass or foam insulation.

In this guide, we'll explore what wool insulation is, how it works, its unique benefits, and why it’s gaining popularity in eco-conscious construction. Whether you're renovating an attic, insulating a van conversion, or designing a passive house, wool could be the smart, sustainable choice.

What Is Wool Insulation?

Wool insulation is made from sheep’s wool—a renewable, biodegradable resource. Unlike fiberglass or foam, wool fibers are safe to handle, non-toxic, and naturally effective at trapping air.

Sheep’s wool has been used for centuries for its insulating properties. In construction, it's often treated with non-toxic borate for added fire, pest, and mold resistance. Wool insulation comes in batt and loose-fill forms, suitable for walls, floors, ceilings, and attics.

Havelock Wool, available at Eco-Building Products, is one of the most recognized brands, offering 100% wool insulation with no synthetic blends or added chemicals.

Benefits of Wool Insulation

1. Superior Thermal Performance

Wool fibers naturally crimp and interlock, creating tiny air pockets that trap heat. This structure delivers consistent R-values and slows heat transfer.

• Batt insulation: R-value ~3.6–4.3 per inch
  
  

• Loose-fill wool: excellent for filling irregular cavities

Unlike synthetic materials, wool continues to insulate effectively even in humid conditions.

2. Moisture Regulation

Wool can absorb up to 30% of its weight in moisture without losing its insulating power. It passively helps regulate indoor humidity levels.

This hygroscopic nature reduces condensation, protecting wood framing from rot and improving comfort in high-humidity climates.

3. Sound Absorption

Wool insulation doesn’t just block heat—it’s also a powerful sound absorber. Its dense, fibrous structure dampens airborne noise, making it ideal for interior walls, ceilings, and floors in multi-unit or urban homes.

4. Natural Fire Resistance

Treated wool has a high ignition point and self-extinguishes when flames are removed. With borate treatment, it meets building code requirements for fire resistance.

Unlike foam, it won’t off-gas toxic fumes when exposed to heat.

5. Non-Toxic and Safe to Handle

There’s no need for protective gear when working with wool. It doesn’t itch, off-gas, or contain formaldehyde or petrochemicals. This makes it a great choice for people with allergies or chemical sensitivities.

6. Pest Resistance

Borate treatment repels insects, rodents, and mold. Wool fibers are unappetizing to pests, unlike cellulose or fiberglass, which can become nesting material.

7. Sustainable and Renewable

Sheep regrow wool annually, and harvesting it has a low environmental impact. Wool insulation is fully compostable and doesn’t persist in landfills.

Brands like Havelock source wool from free-grazing, cruelty-free flocks and use no synthetic binders, offering true cradle-to-cradle sustainability.

Common Uses of Wool Insulation

Wool is incredibly versatile and can be used throughout residential and commercial structures:

• Attics: Batts between rafters or loose-fill on attic floors
  
  

• Walls: Cavity insulation for exterior and interior walls
  
  

• Floors: Under floorboards or between joists for thermal and acoustic control
  
  

• Van conversions: Safe, flexible, and moisture-managing insulation
  
  

• Tiny homes and cabins: Perfect for small, naturally ventilated spaces
  
  

• Soundproofing: Between rooms or studios
  
  

Its flexibility allows it to be stuffed into oddly shaped cavities or around wiring and piping without compromising performance.

How Does Wool Compare to Other Insulation?

• R-value per inch: Wool offers an R-value of 3.6 to 4.3, which is higher than fiberglass (2.2 to 3.7) but lower than foam insulation (5.5 to 7.0).
  
  

• Moisture resistance: Wool has excellent moisture resistance, whereas fiberglass performs poorly, and foam is considered good in this regard.
  
  

• Mold resistance: Wool is resistant to mold when treated. Fiberglass does not resist mold, while foam provides conditional resistance depending on its type and installation.
  
  

• Fire resistance: Wool is self-extinguishing, meaning it does not support flames. In contrast, fiberglass melts under heat, and foam tends to burn and emit toxic fumes.
  
  

• Sustainability: Wool is fully renewable, making it an eco-friendly choice. Fiberglass production is energy-intensive, and foam is petroleum-based, raising environmental concerns.
  
  

• Handling safety: Wool is safe for skin and respiratory health. Fiberglass can irritate the skin and lungs, while foam insulation often requires personal protective equipment (PPE) during installation.

Wool may not have the highest R-value per inch, but it offers real-world performance, especially in varied climates. Its added benefits—like moisture control and ease of use—make it a superior all-around choice.

Installation Considerations

Wool insulation is DIY-friendly and easy to cut with a serrated knife or insulation saw. Key tips include:

• Use a snug fit—don’t compress the fibers
  
  

• Seal around wiring and penetrations
  
  

• Combine with vapor barriers as needed in cold climates
  
  

• Wear gloves if sensitive, though not required
  
  

For batt installation, measure carefully and cut slightly wider than the cavity for friction fit. For loose-fill, fluff the wool and apply evenly with hands or a blower.

Wool also integrates well with air-sealing products like Sealin’ Hatch attic doors and insulated recessed light covers.

Cost & Value

Wool insulation costs more upfront than fiberglass but less than some spray foam options:

• Batt wool insulation: $1.80–$2.50/sq.ft. (installed)
  
  

• Fiberglass batt: ~$0.70–$1.30/sq.ft.
  
  

• Spray foam: $3.00–$7.00/sq.ft.

However, the long-term benefits—including better moisture control, improved air quality, and durability—often justify the investment.

Plus, using wool can help qualify for green building certifications like LEED, WELL, and Passive House.

Environmental Impact

Choosing wool supports regenerative agriculture and sustainable building practices. Brands like Havelock avoid synthetic additives and carbon-heavy manufacturing. At the end of its life, wool insulation can be composted—unlike foam, which lingers for centuries.

Installing wool also reduces reliance on petroleum-based products, supporting the transition to natural materials in the building industry.

Wool Insulation is Ideal if you are a:

• Eco-conscious homeowner seeking sustainable upgrades
  
  

• Tiny home and van builder prioritizing air quality and space efficiency
  
  

• Contractor or architect designing to green standards
  
  

• Allergy-sensitive individual needing toxin-free insulation
  
  

• DIYer who wants a safe, simple insulation material

Conclusion

Wool insulation delivers far more than just warmth. It’s a high-performance material that regulates temperature, controls moisture, absorbs sound, and contributes to healthier indoor environments. Plus, it’s safe, renewable, and good for the planet.

Whether you’re a seasoned builder or a first-time DIYer, wool insulation—especially from trusted names like Havelock Wool—offers a future-proof solution that performs beyond expectations.

Ready to make the switch? Browse wool insulation and other natural building materials at Eco-Building Products today.