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Wood Fiber Insulation

Compressed sawmill softwood waste — vapor-open, fire-resistant, and carbon-storing.

Wood Fiber Insulation — a natural material we specify on every Earth Bound Homes project

Toxicity Screening — All Clear

This material screens clear across all seven independent toxicology authorities we use on every project.

LBC Red List

Not Listed

Prop 65

Not Listed

IARC

Not Listed

NTP RoC

Not Listed

GSPI

Not Listed

REACH SVHC

Not Listed

TSCA

Not Listed

Material Type

Plant-Fiber Compressed Insulation Board & Batt

Material Description

Wood fiber insulation is made by defibrating softwood (typically pine or spruce) sawmill waste and compressing it into rigid boards or flexible batts. The product is vapor-open, which means moisture can move through the assembly rather than being trapped — a major advantage for high-performance wall assemblies that need to dry to one or both sides. Wood fiber is naturally hygroscopic, has excellent decrement-delay properties (it slows summer heat transfer better than its R-value would suggest), and is fully biodegradable. The boards use paraffin wax as a hydrophobic modifier and an ammonium phosphate or borate fire retardant — both well-screened low-hazard chemistries.

Composition & Origin

Defibrated softwood + paraffin wax + low-hazard fire retardant, compressed under heat and pressure

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.

Cancer

1/10

Endocrine

1/10

Reproductive

1/10

Developmental

1/10

Neurological

1/10

Respiratory

2/10

Cardiovascular

1/10

Liver/Kidney

1/10

Skin

1/10

Immune

1/10

Common Forms & Brands

GUTEX Thermosafe & Multitherm boards
STEICO Universal & Therm
Pavatex / Pavabord
Common framing: rigid sheathing-grade board, flexible batt, dense-pack loose-fill

Why We Use It

Vapor-open — allows moisture to migrate through assembly without rotting
Excellent thermal decrement delay for summer comfort
Naturally carbon-storing — sequesters CO₂ for life of building
Biodegradable end-of-life
Dimensionally stable — no settling or shrinkage

Where It Performs Best

Exterior continuous-insulation sheathing
Cavity batts in wall and roof assemblies
Vapor-open roof underlayment
Acoustic and interior partition insulation

Building Applications for Wood Fiber Insulation

Listed alphabetically. Where in a home this material earns its keep.

Cavity Batts (Walls & Roofs)
Continuous Exterior Sheathing
Roof Underlayment
Sub-Floor Acoustic Layer
Vapor-Open Wall Assemblies

Specifying a project? Drop the manufacturer's SDS into our SDS Toxic Chemical Screener to verify any specific product you're considering screens clear on all seven databases.