Second Story Seismic Corner Bracing Garage Door

Studies have shown that walls containing garage doors perform poorly when subjected to lateral wind and seismic forces.

Second story seismic corner bracing garage door.

If preferred install the floor brace after installing the vertical braces. In a single storey house you need to brace at least 50 percent of the length of each cripple wall while in a two story house you need to cover at least 80 percent of the length. When the narrow sections of the wall on each side of the opening are not reinforced or braced the weakness is worse. Install a 2 by 4 on the garage floor at the base of the door to act as a base for the brace with the length extending just beyond the door hinges.

This is especially true when the wall containing the garage door is offset by more than a few feet from other braced wall lines parallel to the garage door see illustration below. The large opening of a garage door and the weight of a second story room built over the garage can result in the walls being too weak to withstand earthquake shaking. For instance in a single story house if the cripple wall is 48 long you need to cover 24 which could be accomplished with a 4 panel at each end and two 8.