Choosing the right insulation for your project can be a balancing act between performance, safety, sustainability and long-term comfort. Natural wool insulation is becoming an increasingly popular choice for those looking to build or renovate more responsibly, but questions sometimes arise around durability and the risk of moth damage. While untreated wool can be vulnerable, high-quality products like Sisalwool are carefully treated using natural methods to guard against infestation, giving you all the benefits of wool without the worry.
In this article, we compare wool insulation with two of the most commonly used synthetic alternatives: fibreglass and foam. From thermal performance and air quality to ease of installation and environmental impact, here’s how they stack up.
| Feature / Property | Wool | Fibreglass | Foam (Polyurethane, EPS) |
|---|---|---|---|
| Thermal Insulation (R-value) |
(approx. R 0.035–0.040 per mm) |
(R ~0.022–0.043 per mm) |
(R ~0.040–0.070 per mm) |
| Air & Moisture Regulation |
Absorbs and releases moisture |
Performance drops when wet |
Requires vapour barriers |
| Sustainability |
Renewable and biodegradable |
Not biodegradable, energy-intensive |
Petroleum-based, not biodegradable |
| Fire Resistance |
Naturally flame-resistant |
Requires chemical treatment |
Flammable unless treated |
| Sound Insulation |
Dense and fibrous |
||
| Allergy/Health Risk |
Hypoallergenic, no microfibres |
Can irritate skin and lungs |
May emit VOCs if not sealed properly |
| Durability & Longevity |
Long-lasting if kept dry |
Can sag or settle over time |
Long-lasting if protected from moisture |
| Ease of Handling |
Easy and safe to install |
Requires protective equipment |
Skilled installation often needed |
| Cost |
Higher upfront investment |
Lower to moderate |
Moderate to high, depending on type |
