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Wall Construction

There are three important concepts to remember for wind-resistant wall construction.

• Walls have to resist the uplift forces caused by the pull of the wind.
• Walls have to resist the shear forces that try to push the walls over.
• Walls have to resist the lateral force of the wind that tries to push the walls in and pull them away from the building

For uplift purposes, walls are the intermediate link between the roof and the foundation below.

To resist uplift forces walls have to have a continuous load path that can be achieved through the use of metal connectors for wood frame construction or a combination of metal connectors, vertical and horizontal reinforcement, and a bond beam at the top of the wall for concrete masonry construction.

Shearing forces

Walls are also subjected to shearing forces that act in the direction the wind is blowing.

As wind blows on a wall, the walls perpendicular to the wall the wind is blowing on, are subjected to these shearing forces and are called shear walls. Shear walls are inherently subjected to the shearing and sliding forces.

Wood frame walls resist these shearing and sliding forces through the action of the wall studs, the wall sheathing (preferably plywood), and a specific nailing pattern.

Concrete masonry walls resist these forces through a combination of concrete masonry units, mortar, and grouted and reinforced cells.

As a result of the walls resisting the shearing forces and being fixed at the base, the walls are subjected to an overturning force, or the tendency to rotate over.

For wood frame construction, this force is resisted through the use of a holdown or tensions tied down. Vertical reinforcement and grouted cells resist the overturning forces in concrete masonry construction.

Wind Ready Walls

Finally, walls have to be capable of supporting the push and pull from the wind.

For wood frame construction, studs have to be sized and spaced accordingly to resist the lateral forces, and have to be securely supported at the top and bottom plates.

Concrete masonry resists the lateral forces by using reinforcement in grouted cells.

Visit www.flash.org or call toll-free (877) 221-SAFE for more information about protecting your home from disaster.