Wall bracing is a construction technique used to improve the structural performance of a building. Bracing systems include wood or steel components that help evenly distribute loads and increase the safety of the structure. While traditional framing can support the weight of the roof and floors above, it is not able to resist lateral stresses caused by wind, earthquakes or other forces. Bracing requirements are set by the International Residential Code Section 602, which have been adopted into the majority of building code laws.
Engineered Versus Prescriptive Bracing
Construction bracing systems can be broken down into two basic types, engineered and prescriptive. Engineered bracing is a system designed by a structural engineer based on the needs of a specific project. Prescriptive bracing is a system chosen based on the experience of the builder or developer, and is less complex and more flexible than engineered systems. In most areas, local building codes dictate which of these two types may be used. Generally, an engineered system is required in areas with high levels of seismic activity or for structures that will be exposed to wind speeds greater than 110 MPH.
Temporary Versus Permanent Bracing
The various types of construction bracing can be further categorised as either temporary or permanent. Temporary bracing uses metal poles, cables, wooden frames or pre-engineered bracing components to keep a structure stable during construction. These items are removed once the permanent bracing is installed. The primary purpose of a temporary bracing system is to keep workers and the public safe during construction. Permanent bracing may be installed at any point during construction, and is designed to keep occupants and the public safe over the life of the building.
Rigid Foam Bracing
One of the more widely used permanent bracing methods involves the use of rigid foam to brace the building's exterior walls. Using this system, framing studs are covered by sheets of foam insulation that are at least 1-inch thick and 4 feet wide. This type of bracing has the added bonus of adding a high level of insulation to the home, and helping to block sound transmission through walls. Foam bracing can only be used in one or two-story buildings, and is fairly labour-intensive.
Structural sheathing bracing systems rely on OSB or plywood sheets to provide lateral support to the framing system. These sheets of wood are nailed to regular framing members, and are covered by moisture barriers and exterior siding or finishes. Since these boards are relatively strong, they are very flexible when it comes to bracing. They can be installed in any direction, and sizes are not typically regulated. Structural fiberboard panels may be used for additional strength and insulation.
Gypsum board, or drywall sheathing, is a popular method of bracing homes from the inside. Rather than use traditional 3/8-inch drywall, 1/2-inch or thicker sheets are used to provide structural support and lateral strength. Instead of installing the bracing on the outside of the building, the drywall is installed on the inside of the framing. These sheets are then finished and painted to provide a normal wall appearance. This system eliminates the need for exterior sheathing, and can help lower project costs.