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.
Concord, New Hampshire
Brookline Workforce Housing
Builders Installed chose TimberFill for the Brookline Workforce Housing initiative in Concord, NH–three buildings, 123 units. The team installed 53,670 sq ft of R49 open-blown attic insulation and 42,045 sq ft of R21 dense-packed wall insulation, delivering code-compliant, healthy, comfortable homes. Phase one brings affordability to 39 units: 31 at ≤60% AMI, 4 at ≤50% AMI, and 4 through the Section 811 PRA program (≤30% AMI) for individuals with severe mental illness.
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?
Contact Support
Our support team is ready to provide answers to your questions or concerns.
Contact Support