Blocking for l-ioist floors

What is it and where should it be used?

f-:otsr FLooRS are often installed lwith blocking. a rectangular piece of engineered wood or a section of Ijoist that is placed between adjacent joists at various locations. For these applications, blocking has three major functions:

. To provide lateral support to the floor joists-to prevent them from physically "rolling over" due to lateral loads. This is accomplished by the shape and stiffness of the blocking panel.

To provide a means of transferring shear loads from the walls above to the floor/foundation below. This is accomplished by nailing into the foundation sill plate or wall top plate through the bottom flanges when Ijoists are used for blocking. When APA Performance Rated Rim Boards or I-joist-compatible structural composite lumber (SCL) is used, shear transfer is accomplished by nailing into the end-grain at the top of the blocking panel and by using toe-nails or framins anchors at the bottom of the blocking panel.

. To provide a means of transferring vertical loads from the wall above to the foundation/floor below. The blocking is used in bearing to accomplish this.

While local code requirements vary, the International Building Code (IBC) and International Residential Code (IRC) are specific in their requirements for blocking of floor joists:

In Section R502.7, the IRC requires full-depth solid blocking, attachment to the rim board/rim joist, or attachment to an adjoining stud (i.e., balloon framing) of joists at each end. In Seismic Design Categories Do, Dt, and D2, similar lateral restraint is required at all intermediate supports as well.

Section 2308.8.2 of the IBC requires full-depth solid blocking, attachment to rim board/rim joist, or attachment to an adjoining stud (i.e., balloon framing) of joists at each end and at intermediate supports for all locations and all applications.

Blocking panels are normally sitefabricated out of engineered wood products on hand. Sections of APA Performance Rated I-joists, APA Performance Rated rim boards, or Ijoist compatible SCL can be used for blocking. It is essential that engineered wood products be used with an I-joist or any other engineered wood floor framing because the shrinkage anticipated with the sawn lumber would affect its ability to perform the vertical load-transfer function and could seriously impede its ability to transfer shear loads.

Fabricate the blocking panels from engineered wood products of I-joistcompatible sizes and cut to fit tightly between the floor joists.

Following are recommendations for blocking of I-joist floor systems designed in accordance with APA Ijoist standard PRI-400:

. Blocking panels are required at each end of the floor joists not otherwise restrained from overturning by a band joist or rim board.

. Blocking panels are required between floor joists supporting loadbearing walls running perpendicular to the joists.

Blocking panels are required between floor joists at the interior support in all locations when regulated by IBC or in Seismic Design Categories Do, Dr, and D2, when regulated by IRC.

. For a load-bearing cantilever, blocking panels are required between floor joists at the exterior support adjacent to the cantilever.

Install blocking panels in accordance with diagram below.

For more tips on I-joist installation, visit www.apawood.org and search "Builder Tios."

A PA Now oFFERS its Builder Tips la,series in a mobile format optimized for viewing on mobile devices, including tablets and smartphones.

Each Builder Tip addresses a single common topic or challenge in today's building environment, such as panel buckling, squeaky floors, nail pops, glulam beam checking, and finishing APA-rated siding.

The new mobile Builder Tips are valuable tools with a "back-to-basics" emphasis on key construction recommendations, noted APA market communications director Marilyn Thomp- son. "We know that the labor shortage in the construction sector will result in a surge of relatively inexperienced builders and framers who need simple, easy-to-use information and training," she said. "By making our Builder Tips more accessible to tablet and smartphone users, we're confident we can get our key construction recommendations out to more contractors."

The straightforward how-to articles. each paired with accompanying diagrams, are designed to help building professionals save money and improve quality on the job through proper construction practices. For example, "Construct a Solid, Squeakfree Floor System" describes how to prevent squeaks, buckling and nail pops, and the callbacks that result from these problems. Simple construction steps, such as using dry material, are detailed.

In "Prevent Buckling With Proper Spacing," readers learn the consequences of improper panel spacing and receive a helpful tip for ensuring they're achieving the recommended l/8" gap.

"Proper Storage and Handling of Glulam Beams" reveals best practices for loading, racking, packaging, and transporting glulam to ensure maximum performance upon installation.

The new mobile-friendly format allows Builder Tips to be browsed, opened and viewed at www.apawood.org/buildertips from Internetconnected devices in the office or field. Seven Builder Tips have already been optimized for mobile viewing, with more to follow soon.

All Builder Tips are still available for free download in PDF format (optimal for printing or saving for offline viewing) from APA's Publications Library at www.apawood.org.