Whats a Wind Load?

Claudette Reichel  |  6/24/2008 2:40:33 AM

Figure 1, Load Forces on House

Preventing wind damage involves strengthening areas where things could come apart. The walls, roof and foundation must be strong, and the attachments between them must be strong and secure. For a home to resist hurricane and weak tornadic winds, it must have a continuous load path from the roof to the foundation -- connections that tie all structural parts together and can resist types of wind loads that could push and pull on the house in a storm.

Imagine turning your house upside down and shaking it. That is essentially the kind of stress that hurricane force winds put on a house. The weak link in the load path is what’s most likely to fail. Wind exerts three types of forces on your home: (Figure 1, Load Forces on House)

  • Uplift load - Wind flow pressures that create a strong lifting effect, much like the effect on airplane wings. Wind flow under a roof pushes upward; wind flow over a roof pulls upward.
  • Shear load – Horizontal wind pressure that could cause racking of walls, making a house tilt.
  • Lateral load – Horizontal pushing and pulling pressure on walls that could make a house slide off the foundation or overturn.

The actual effects of these wind forces on houses depend on their design, construction and surroundings. Among other things, high wind pressures tend to collapse garage doors, window units and patio doors, rip off roofing and roof decking and destroy gable end walls. Roof overhangs, awnings, porches and other features that tend to trap air beneath them, resulting in high uplift forces, are particularly susceptible to damage. In addition, broken windows and doors can expose your home to serious damage from internal wind pressures and water entry.

Check the wind zone of your location (see Geographic Basics), and use the protections that will help your home resist the design wind speed of your region or of a region closer to the coast. Louisiana’s coastline is receding, which means many south Louisiana homes are getting closer to open water.

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