TimberFill Insulation
Dense Pack and Attic Blanket Blown-in Insulation
TimberFill is a debris-free dense pack and loose fill wood fiber insulation proven to protect the building envelope by helping regulate temperatures and humidity – even in the toughest climates.
Download Spec Sheet
TimberFill Insulation Technical Specifications
| PROPERTY | VALUE |
|---|---|
| R-Value of Loose Fill at 75o F Mean Temperature | Approximately 3.4 per inch |
| R-Value of Dense-Pack at 3.5 lbs / cubic foot | Approximately 3.8 per inch |
| Thickness of Loose Fill | Up to 20.7 inches settled thickness |
| Thickness of Dense-Pack | Up to 9.26 inches installed thickness |
| Fire Resistance | ASTM E84 Class A <25 Flame and <450 Smoke spread |
What Is the Best Insulation for Attic Replacement Projects?
The best insulation for an attic replacement project depends on factors such as thermal performance, air sealing strategy, moisture management, and long-term durability. Dense-pack insulation is commonly used in attics because it fills gaps and irregular spaces while helping reduce air movement within the assembly. Wood fiber dense-pack or loose fill insulation offers thermal performance, sound control, and vapor permeability, allowing roof and attic assemblies to manage moisture while maintaining energy efficiency. It can be used in both retrofit and new construction projects where building performance and material sustainability are important considerations.
Fire-Resistant
Achieves ASTM E84 Class A for flame and smoke spread through the use of liquid borate, which saturates the wood fiber and provides a superior long-term solution for fire, bug, and moisture/mold resistance.
High Thermal Performance
All-season thermal storage and draft reduction meets Passive House, LEED, and energy stretch code targets.
Acoustic Comfort
Excellent sound absorption supports privacy and comfort in multifamily and commercial interiors.
Lowers Carbon Footprints
Wood fiber insulation naturally stores atmospheric carbon throughout its entire lifecycle, lowering the carbon footprint of the built environment.
Vapor-Open
Provides wind-tight and water-resistant performance that repels moisture without trapping humidity, reducing the potential for mold, rot, or condensation and improving indoor air quality.
Safe to Handle
Itch-free and has no VOCs, formaldehyde, or added toxins. Declare labeled and Red List Free.
TimberFill is hands down the best product on the market. It is by far the most superior blow in product available. We fought for months trying to get this product here in the midwest. When we were finally able to get it, we were over the moon. We immediately contacted TimberHP for installation specs. With guidance on machine recs and settings, this product cut our installation time down drastically and made our experience 100x better. Walking away from blowing in we didn’t have negative respiratory side effects and had zero itch!
We were highly impressed with how easy it was to feed and blow. The product dispersed so well in the attic and laid in far superior to other products. We had 68 bags blown in within 1 hour 15 mins. We traditionally use Fiberglass blown in and have pushed for an industry change. We don’t like cellulose due to its high dust, dirty, low-quality properties. With TimberFill, our high efficiency builds benefit from the improved attic insulation. TimberFill gives us our great R value, clean insulation, fireblock, green insulation.
Kyle Debettignies
Principal, KD Construction
Applications
TimberFill is suitable for use in both new construction and renovation projects.
Attic Blanket
As a loose fill attic insulation, TimberFill provides seamless coverage and exceptional thermal performance, helping protect the building envelope by regulating attic temperatures year-round while allowing moisture to escape naturally.
Floor, Ceiling, and Cavity Wall Insulation
Dense-packed into cavities, TimberFill creates a high-performing, airtight thermal layer that controls temperature and humidity while reducing sound transmission across walls, floors, and ceilings.
Downloads
**TimberFill’s 25 lb bag was discontinued on July 14, 2025. Please confirm bag weight before use and refer to the correct coverage chart.
TimberFill 25lb Bag Coverage Chart (discontinued)
Installation
TimberFill insulation is designed for ease of use on site.
Download our full Installation Guide, or watch our installation how-to videos for step-by-step details and best practices.
TimberFill Insulation FAQs
Q: What code compliance does TimberFill meet?
A: TimberFill meets IRC and IBC insulation requirements and ASTM fire and vapor standards. For third-party testing documentation, see downloads.
Q: Can I use TimberFill insulation in commercial construction?
A: Absolutely. TimberFill is well suited for commercial interiors, as well as multifamily housing, schools, and offices. Reach out to our team for assemblies and detailing support.
Q: Is TimberFill fire-resistant?
A: Yes, TimberFill and all TimberHP wood fiber insulation products are fire resistant. TimberFill achieves a ASTM E84 Class A rating for flame and smoke spread – the highest fire resistance rating for building materials – and is treated with liquid borate, which saturates the wood fiber and provides a superior long-term solution for fire, bug, and moisture/mold resistance.
Q: What’s the difference between TimberFill and TimberBatt?
A: TimberFill is a loose-fill and dense-pack insulation alternative for open blow applications. TimberBatt is a batt insulation designed for framed cavities.
How Can We Help?
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