Material · Wood · Assembly
Wood-Fiber Insulation
Gutex, Steico, TimberHP · rigid boards, batts, and blow-in
Insulation made from wood chips and sawmill residuals pressed into vapor-open boards, batts, or loose fill. It insulates like conventional products while adding two things foam cannot: humidity buffering and serious summer heat delay.
Why it matters
High-performance walls live or die by moisture management, and wood fiber is the insulation that forgives: vapor-open enough to let assemblies dry, hygroscopic enough to buffer moisture spikes, dense enough to delay summer heat waves through the wall by hours (phase shift). It is standard practice in European passive houses and now domestically produced in the US. The health story is what it lacks — no isocyanates, no blowing agents, no fiberglass itch.
Benefits
- Vapor-open: assemblies can dry in both directions — the forgiving wall
- High density delays summer heat transfer by hours (phase shift comfort)
- Buffers humidity swings within the assembly
- Meaningful acoustic damping in walls and floors
- Carbon-storing, compostable, no hazardous handling
Best applications
Rooms: Whole home
Performance
Watch-outs
- Costs more than fiberglass or cellulose per R
- Must be detailed in a vapor-open assembly — pairing it with interior poly sheeting wastes the point
- Heavier than fiberglass; framing and fastening schedules differ for exterior boards
- US availability improving but still region-dependent
What to verify
Finish, binder, sourcing, and installation conditions to confirm before specifying.
- Assembly design is vapor-open end to end — no interior poly
- Correct product type: rigid exterior board vs cavity batt vs blow-in
- Binder disclosure on the specific line
- Fire strategy per code — wood fiber chars predictably but needs the right assembly rating
Certifications to look for
The labels that separate the real material from the marketing version.
Declare / EPD
Several manufacturers publish full ingredient and environmental product declarations
FSC / PEFC
Residual-wood chain of custody
Sources
Information verified July 2026.