The recent movement to relax or change building codes to permit wood framing at heights above the typical four-story limits has been driven by the relentless pursuit of cheaper construction methods and materials. And credit the wood industry for capitalizing on the economic pressures many builders face by successfully introducing three very significant revisions to the 2006 model building code.
The first of these changes increased the allowable heights of wood framed buildings from 50 feet to 70 feet. Another crucial revision was to allow fire walls constructed of combustible materials (wood) to be used in Type V buildings, which prior to then had required non-combustible (steel) or fire-resistive (concrete). The justification was that once the sprinklers were installed and the fire-resistant gypsum board was applied to the framing member, it didn’t matter what was in the wall cavity. The third important change was in the evolution of the definition of a fire wall. Starting in the 2006 codes, a fire wall was no longer considered to be just a separation of fire areas within a building, but also to allow the division of the structure into separate buildings, each subject to its own height and area limits.
Together, these revisions have enabled the proliferation of large multifamily and retail projects where structures up to 70 feet tall are being built with five stories of combustible wood framing installed over a one- or two-story podium of noncombustible steel or concrete. As stated in wood industry promotions: “It (changes to the building codes) opens many new opportunities for design using wood-frame construction.”