When a homeowner considers a new townhome purchase, safety is always top of mind. With the Greenfiber SANCTUARY® Two-Hour Firewall, you can build a better safety, sound, and odor barrier for your clients.


Originally rated by Underwriters Laboratory in 2002, the SANCTUARY® Two-Hour Firewall uses Greenfiber® FRM spray-applied cellulose insulation for a defect-free installation, currently available in select markets.

  • Streamlined Installation

    Because Greenfiber FRM insulation is blown in after the roof goes up, conventional framing is possible. That means, in addition to being protected from the elements, the SANCTUARY Two-Hour Firewall allows all trades to work simultaneously, which normalizes the sequence of construction.

  • Improved Compliance

    To meet stringent energy efficiency codes, the SANCTUARY Two-Hour Firewall utilizes spray-applied Greenfiber FRM Insulation that completely fills gaps, voids and hard-to-reach places, reducing unintended airflow. This lowers the air changes per hour, eliminating customer callbacks.

  • Enhanced Comfort for Homeowners

    Because the SANCTUARY Two-Hour Firewall fills gaps so completely, sounds and odors are blocked between neighboring units. Homeowners have much more control over their own indoor air quality, which allows them to live more comfortably.

Assembly 2X@2X


The SANCTUARY Two-Hour Firewall is constructed of two opposing and offset studded walls. Studs on each wall are set to standard 16 inches on center distance. When offset, the actual distance between opposing studs is 8 inches on center, creating an 8-inch cavity into which Greenfiber FRM Insulation is spray-applied.

The SANCTUARY Two-Hour Firewall is perfect for townhomes due to faster construction, reduction of unintended airflow and minimized trade activity. Its high STC 61 rating also makes it one of the most effective sound blocking firewalls available to the building industry.

  • STC 61

    • 2x4 double wall 16” on center staggered.
    • 3.5” gap between walls.
    • FRM100 spray-applied single layer 5/8” sheetrock type C.
    • Fire rating: 2HR: U/GA# U370
    • STC testing RAL TL06-329
    STC 61
  • STC 56

    • 2x4 double wall 16" on center staggered.
    • 1" gap between walls.
    • FRM100 spray-applied 5/8" sheetrock type C.
    • Fire rating: 2HR: U/GA# U370
    • STC testing RAL TL06-199
    STC 56

Technical Documents

  • Greenfiber Fire & Sound Assembly Brochure
    Product Brochures
    5.1 MB | PDF
  • Two-Hour Firewall Checklist
    Certificates & Forms
    474.76 KB | PDF
  • Two-Hour Firewall Field Test Form
    Certificates & Forms
    469.29 KB | PDF
  • SANCTUARY 2-Hour Firewall Installation Guide
    Installation Guides
    787.83 KB | PDF
  • SANCTUARY 2-Hour Firewall Installation Guide - Spanish
    Installation Guides
    754.91 KB | PDF
  • SANCTUARY 2-Hour Firewall Townhome Advantages Sell Sheet
    Product Brochures
    3.03 MB | PDF
  • SANCTUARY Two-Hour Firewall Specification Sheet
    Product Brochures
    245.39 KB | PDF

Get Additional Technical Documents & Support

More Helpful Information

  • Fire & Sound Brochure

    For detailed information on all of our UL listed firewall assemblies and best practice design details contact us today.

  • AEC Daily Course

    Learn about Greenfiber® FRM insulation with these educational resources for builders and architects.

    Learn More
  • UL Certification

    Get UL certification information on our proprietary UL listed SANCTUARY Two-Hour firewall, the UL-U370 assembly.

    Learn More

Trusted Installation Partners

The SANCTUARY Two-Hour Firewall is currently available in select markets. Contact us today for more information.