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Here in Seattle, we get occasional good-sized earthquakes that can damage the unreinforced masonry buildings common in some areas of the city. Recently my company completed a six-week job stabilizing the facade of a double-wythe structural brick apartment building. The repairs were not meant to be permanent; instead, the idea was to buy some time until the owner decides whether to make more extensive repairs or demolish the building. The inner wythe was in decent condition, but the bricks outside were spalling and deteriorating; the mortar crumbled when prodded with a screwdriver. Worse, the facade was gradually peeling away from the inner bearing wythe, leaving gaps up to 8 inches wide between the two layers in some spots.
The engineer’s plan called for tying the exterior masonry to the existing floor framing with sections of threaded rod fastened to the floor joists. These tie rods — spaced 6 feet apart at each floor level — would extend through holes bored through both layers of brick to steel tie plates at the outside face of the building.