What is wall
bracing?
A system of specially constructed exterior, and often interior, wall segments attached to the roof, floor and foundation that resist lateral (sideways) loads from wind and earthquakes.
Wall Bracing Requirements
Wall bracing requirements are based on code provisions from
the International Residential Code (IRC), the International Building Code (IBC)
and the Uniform Building Code (UBC). The majority of the country uses the IRC
to brace residential homes. All codes require wall bracing in conventional
light-frame wood construction. The IRC has 8 traditional methods and two newer methods that provide narrower alternatives. In general, the 8 options require a minimum of a 4' x 8' panel of
specified material nailed into stud framing at a specified location with a specified
stud quality required. The most common wall bracing is a 4' x 8' sheet of wood structural panel sheathing (OSB or Plywood) nailed over studs 16" to 24" on center. With the number of windows and doors in
today's home designs, it is sometimes difficult to fit
in four continuous feet of wall to act as a brace. In these cases, alternate methods
and prefabricated panels are often employed. To find specific information
regarding conventional wall bracing, see Conventional Wall Bracing.
Prescriptive vs.
Engineered
In most residential construction, prescriptive design is allowed
using the IRC requirements as a 'menu' of building options. When using prescriptive design, a Design Professional of Record (DPOR) is not required. In general, areas with a Seismic Design Category (SDC) of D2 or less and a wind speed category under 110 mph allow for prescriptive design. Some large or complex custom homes may require a DPOR simply because the design is such that
IRC methods cannot support the structure. A DPOR is usually required for homes built in SDC greater than D2 and wind zones above 110 mph. Additionally, some counties or municipalities
require a DPOR for all homes built in those areas. It is always best to check with a local building official to determine if a plan for a particular area can be built using prescriptive design. |
