Huntsman Building Solutions, a global leader in high performance, sustainable building envelope solutions, today introduced W-Wall™, a fire-safe load-bearing wall assembly utilized for partition walls between attached multifamily and townhome units. A design solution created specifically for architects and builders, W-Wall is the first two-hour fire rated load-bearing wall assembly tested and approved for use with open cell spray foam. All Huntsman Building Solutions’ open cell spray foam insulation solutions have been certified for use with W-Wall, providing sound attenuation and energy efficiency capabilities as part of the assembly solution. Use of the assembly design meaningfully reduces construction and labor costs.

“W-Wall provides architects and builders with a partition wall assembly design that is already tested and certified for use with open cell spray foam and which enhances fire safety and acoustical performance,” says Doug Brady, vice president of global innovation and product management with Huntsman Building Solutions. “Providing an air seal and sustainable soundproofing capabilities, this assembly solves blower door issues and provides comfort and ease-of-mind to the residents living on either side of it.”

The W-Wall Assembly design incorporates a series of materials in addition to Huntsman Building Solutions’ open cell spray foam insulation. All of the materials include: wall sheathing consisting of two layers of 5/8” Type X Gypsum wallboard on each side of the assembly; walls constructed with 2x4 studs at 16” on-center (no need for 8” off-set); sheathing secured with screws, and the finished layer covered with tape and joint compound; one side of the wall leaf filled with 3.5” of Huntsman Building Solutions open cell spray foam insulation; and a 1” air gap between the two wall leafs. The overall assembly is 1” thinner than the typical shaft wall.

W-Wall is assembled at the construction site by framers and/or spray foam contractors. W-Wall is fire rated for two hours, passing ASTM E119 in accordance with IBC requirements, making it the first spray foam wall assembly solution of its kind to pass. The W-Wall assembly also notably allows for easy installation and an overall quicker build as compared to alternate partition wall solutions, essentially reducing labor costs. 

“The benefits of W-Wall are clear when you consider the long-term performance consistency of spray foam, and the reduced labor costs and improved assurances of meeting construction milestones that come with it,” adds Brady. “This assembly design is essentially a simpler, better solution for architects and builders. It’s also faster and easier to install.”

Many of Huntsman Building Solutions’ open cell spray foam insulation solutions have been successfully certified for effective use with W-Wall. These high-performance insulations include: Sealection 500, Sealection NM, FOAM-LOK 450, FOAM-LOK 500, OC NO-MIX, Classic Ultra Select, Classic Plus and Classic Ultra.

Additional certifications of W-Wall include: ASTM E90-STC 57, ASTM E2178 Air Permeance, ESL 1373 - ICC Evaluation Service Listing, and TER 2011-01 – Technical Evaluation Report. W-Wall is also, depending on the installed products, Greenguard Gold certified, indicating low VOC emission, ensuring better indoor air quality

To explore W-Wall, visit