Written by Natural Insulation: Warmer Homes, Smaller Footprints
When you think of insulation, the usual suspects come to mind: fibreglass batts, spray foam, maybe rigid boards. They work, sure, but they also come with a heavy environmental cost — energy-intensive production, tricky recycling, and potential off-gassing in your living space.
Natural insulation offers another path. These materials come from renewable or recycled sources, often require less processing, and can actually help regulate the health of your home by managing moisture and air quality. Let’s dig into what’s out there, what it costs, and how tricky (or not) it is to work with.
Common Types of Natural Insulation
Here’s a quick look at the most common options, their strengths, and where they shine:
| Insulation Type | R-Value per Inch* | Pros | Cons | Best Uses |
| Sheep’s Wool | ~3.5–3.8 | Renewable, moisture regulating, fire resistant (with treatment) | Higher cost, can attract moths if untreated | Walls, attics, retrofits |
| Cellulose (Recycled Paper) | ~3.2–3.8 | Recycled content, good air sealing, affordable | Can settle over time, moisture sensitive | Walls, attics (blown-in) |
| Cotton/Denim | ~3.0–3.7 | Recycled textiles, safe to handle, good sound absorption | More expensive, less available | Walls, interior partitions |
| Hemp | ~3.5–3.7 | Fast-growing, pest resistant, good soundproofing | Limited availability in N. America, pricier | Walls, attics |
| Cork | ~3.6–4.2 | Renewable, good thermal and sound insulation, resists rot/pests | Expensive, availability varies | Floors, walls, acoustic panels |
| Straw Bale | ~2.4–3.0 | Very low cost, renewable, excellent thermal mass | Thick walls, moisture protection needed | Whole wall systems, natural builds |
| Wood Fiberboard | ~3.0–3.7 | Renewable, vapor permeable, good sound absorption | Can absorb water, needs weather protection | Walls, roofs, sheathing |
| Expanded Cork Panels | ~3.6–4.2 | Natural, durable, carbon negative | Expensive, imported in some regions | Exterior insulation, soundproofing |
| Mycelium (Experimental) | ~3.0–3.5 (est.) | Biodegradable, grown not manufactured | Not yet mainstream, durability testing ongoing | Specialty panels, eco-projects |
*R-values vary by density and manufacturer.
Cost, Carbon, and DIY Considerations
Not all “green” options are equal. Some are affordable and widely available; others are experimental or high-end imports. Here’s a deeper look at cost, carbon impact, sourcing, and how DIY-friendly each material is:
| Insulation Type | Typical Cost (per sq. ft. @ R-19)* | Carbon Impact | Sourcing Considerations | DIY Difficulty |
| Sheep’s Wool | $2.75–$4.00 | Low – renewable, biodegradable | Often imported unless local farms/processors exist | Easy |
| Cellulose (Recycled Paper) | $0.75–$1.50 | Very low – recycled paper, low energy input | Widely available, often local | Moderate (requires blower) |
| Cotton/Denim | $1.25–$2.00 | Low – recycled textiles | Depends on regional recycling streams | Easy |
| Hemp | $1.75–$3.50 | Very low – fast-growing crop | Limited N. American production; more EU suppliers | Easy–Moderate |
| Cork (loose fill/granules) | $3.00–$5.00 | Very low – harvested bark, renewable | Imported in many regions | Moderate |
| Straw Bale | $0.50–$1.25 (material only) | Very low – agricultural byproduct | Locally available in farm regions | Advanced (structural build) |
| Wood Fiberboard/Panels | $1.75–$3.00 | Low – wood waste product | More available in EU; limited N. America | Moderate |
| Expanded Cork Panels | $4.00–$6.00 | Carbon negative – sequesters carbon | Imported from Portugal/Spain | Moderate |
| Mycelium (Experimental) | Prototype pricing; niche | Very low – grown not manufactured | Early-stage suppliers | Easy–Moderate |
*Costs are ballpark averages for North America, 2024–2025.
So, Which One Should You Choose?
- On a budget? Cellulose is the most cost-effective natural option and works well for retrofits.
- Looking for low-carbon and easy DIY? Wool, hemp, and denim are safe to handle and good for small projects.
- Building from scratch? Straw bale or wood fiberboard can form the bones of an entire wall systeCm.
- Soundproofing or specialty projects? Cork (granules or panels) shines, while mycelium is a fun experimental option if you can source it.
The Bigger Picture
Insulation isn’t just about keeping warm. It’s about cutting energy bills, reducing climate impact, and building healthier spaces. Natural options prove that you don’t have to rely on petrochemicals to get there.
If you’re planning a renovation or a new build, keep these alternatives on your radar. They may cost a little more up front, but the long-term comfort — and the smaller footprint — are worth it.