Wall Bracing Calculator
Wall Bracing Calculator


The wall bracing provisions as defined in the 2009 IRC are more complex than those presented in years past. To determine the wall bracing amount a series of calculations must be completed using variables obtained from tables in the IRC. The variables are based on how the home will be constructed, and on its potential exposure to damage. A home that is located in a hurricane-prone or seismically-unstable region, for example, will require longer wall-bracing lengths than a home in an area less prone to natural disaster. Moreover, the taller the structure, the greater its exposure to wind forces and the more bracing it will need.

In an effort to assist Designers with the IRC wall bracing provisions, Simpson Strong-Tie has developed this calculator, which features inputs for all of the variables which are needed to determine the required bracing amount. Please note that while the calculator does simplify the process of determining the required bracing, it is intended for use by an individual who has a firm understanding of the braced wall design provisions of the IRC. The tutorial that follows will guide you through each step of the calculator.

Step 1 – Determine the Seismic Design Category

The seismic design category is a way of measuring the earthquake hazard in a given region. Buildings are assigned a Seismic Design Category (SDC) in accordance with their location on the map shown in IRC Figure R301.2(2). Note the following:

Step 2 – Establish the Basic Wind Speed

The Basic Wind Speed is a design parameter that represents a home's potential exposure to a hurricane, as determined by its location on the map in IRC Figure R301.2(4). Note the following:

Step 3 – Identify the Wind Exposure Category

The Wind Exposure Category reflects the characteristics of the ground surface surrounding the home. If the home is surrounded by several similar-sized objects, then the wind won't affect it as much as it would if the home were out in the open. The IRC defines the following exposure categories (see Section R301.2.1.4):

Step 4 – Identify Braced-Wall Lines

Identifying the braced-wall-line design information is probably the single most critical step in developing a bracing plan for the home. This step should be completed by an individual trained in the IRC braced-wall provisions. As such, a detailed explanation of how to identify braced-wall-line information is outside the scope of this tutorial; however, the calculator does require the following definitions inputs:
(Click on the following terms for more information.)

Step 5 – Define Other Variables

The final step in using the calculator is to identify miscellaneous variables about the home construction, as follows:
(Click on the following terms for more information.)