III. Structural Problems and Strengthening Methods F. House Over Garage

Second stories built over garages are vulnerable to damage and collapse. Many garages have large door openings and therefore do not have the strength to brace the floor above against shaking in an earthquake. When there is 30" or more of wall space on both sides of the garage door opening, it may be possible to strengthen this configuration by attaching plywood panels to the wood stud walls on both sides of the opening (see figure). This applies to an 8' ceiling, but the required width will vary according to the height of the wall and other factors. In order for the panels to be effective, their height must he less than 3.5 times their width. The new panels should be supported by blocking on all sides and should follow the requirements of the local building code.

Typical Cost: $24/lf of 8'-high wall panel

When there are no walls on the sides of the garage door, a steel frame can be added around the opening and tied to the wood structure, or a new wall can be constructed next to the garage to brace this portion of the building. This method will require engineering design.

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