Simple strategies to meet the IRC’s new fire-protection requirements

April 24, 2015

Last year, nearly 30 percent of new homes in the U.S. had partial or full basements, according to the Census Bureau’s Survey of Construction. The heaviest concentration continues to be in the Northeast and Midwest, where more than 70 percent of new homes were built atop basements.

The 2012 International Residential Code (IRC) brought significant changes to fire protection requirements for the floor systems above basements. Section R501.3 of the code requires that floor assemblies, not required elsewhere in the code to be fire-resistance rated, must now include a 1/2-inch gypsum wallboard membrane, a 5/8-inch wood structural panel membrane, or the equivalent on the underside of the floor framing member.

Often referred to as “membrane protection” requirements, the code also allows several exceptions, including homes with an automatic sprinkler system or floors installed over some crawl spaces.

Many states have already adopted similar language to the 2012 code. They include:

·      Pennsylvania – Act 1 of 2011

·      Ohio – RCO Section 502.14

·      Massachusetts – 8th Edition 780 CMR, Chapter 51, R501.3

Other states that have adopted membrane protection requirements in at least some jurisdictions include Alabama, Colorado, Illinois, Iowa, Kentucky, Maine, North Dakota, Tennessee, and West Virginia. Verify existing or pending requirements with your local building official.

Simple Solution

While a gypsum or wall panel membrane can be used to meet the new requirements, Weyerhaeuser has developed an economical and hassle-free solution: Trus Joist® TJI® Joists with Flak Jacket® protection, which feature a proprietary coating that enhances the joists’ fire resistance and enables the floor assembly to meet these new membrane protection requirements.

The Flak Jacket coating, which puffs up when exposed to fire, thereby protecting the engineered wood underneath, meets the 2012 IRC by providing fire endurance equivalent to dimension lumber. It eliminates the need to install either fire sprinklers or gypsum board in basement ceilings, which saves added labor, and avoids substituting an uncoated joist with 2x10 dimension lumber, which may not have the same strength properties, length availability, consistency and straightness as an engineered product. Installing TJI Joists with Flak Jacket protection also allows builders to keep their standard design and maintain their existing building practices.

For more information, visit, download a Product Overview or Frequently Asked Questions, contact our Technical Support team or call 888-453-8358.

Glyn Boone, PE is a Senior Engineer for the Weyerhaeuser Trus Joist engineered wood products team. He has B.S. and M.S. degrees in Agricultural Engineering from Penn State University and is a registered engineer with 28 years of professional experience in wood design and residential construction.