Cork Insulation
Bark of the cork oak compressed into rigid board or loose-fill — antimicrobial without additives.
Toxicity Screening — All Clear
This material screens clear across all seven independent toxicology authorities we use on every project.
Material Type
Tree-Bark Renewable Thermal Insulation
Material Description
Cork insulation is the same renewable cork bark used for flooring and wine stoppers, expanded and bonded into rigid insulation board with no added binders — the suberin in the cork bark itself acts as the natural binder under steam heat. The cellular structure is ~50% air by volume, giving R-3.6 to R-4.0 per inch. Cork is naturally antimicrobial via its suberin content, fire-resistant (it chars rather than burns), water-shedding, and biodegradable at end of life. EBH specifies cork for exterior continuous insulation where vapor-open performance matters, and as acoustic underlayment.
Composition & Origin
Health Profile — All Endpoints Clear
Severity scored 0–10 against the same 10 hazard endpoints we use for the chemical families on the avoid list. Every score is 1–2 — essentially no signal across every endpoint.
Common Forms & Brands
- ThermaCork rigid insulation board
- Amorim Insulation Cork Board
- Aerocork loose-fill cork
- Common framing: rigid exterior continuous insulation board, acoustic underlayment, loose-fill
Why We Use It
- Renewable — harvested without cutting the cork oak
- Self-binding via suberin — no added formaldehyde or isocyanate adhesive
- Naturally antimicrobial and mold-resistant
- Fire-char layer slows combustion
- Carbon-negative life cycle
Where It Performs Best
- Exterior continuous insulation on walls and roofs
- Below-grade insulation (water-tolerant)
- Acoustic underlayment beneath finished floors
- Sub-slab thermal break
Building Applications for Cork Insulation
Listed alphabetically. Where in a home this material earns its keep.
Below-Grade Foundation Insulation
Exterior Continuous Wall Insulation
Floor Acoustic Underlayment
Roof Sheathing Insulation
Sub-Slab Insulation Layer