Q. It’s not unusual for a foundation to be slightly out of square. If the house has brick veneer siding, it’s sometimes necessary for the first course of bricks to overhang the concrete foundation. What is the maximum safe overhang in such a situation?
A. Consulting architectural engineer Clayford Grimm responds: To provide structural stability, at least two-thirds of a brick masonry wythe should bear on the foundation. Three-inch brick veneer should not overhang the foundation by more than 1 inch, and 3 5/8-inch brick veneer by not more than 1 1/4 inches.
One reason this condition occurs fairly often is that the American Concrete Institute’s Standard Tolerances for Concrete Construction and Materials (ACI 117) provides that footings may be misplaced as much as plus or minus 2 inches. One solution to a misplaced footing is to relocate the wall. The Specifications for Masonry Structures written by the Masonry Standards Joint Committee (MSJC99) provides that the location of walls may differ from the intended location by as much as plus or minus 3/4 inch. So as long as the wall location can be adjusted in the right direction, it is possible for 3 5/8-inch brick veneer to stay within the allowable tolerances for both masonry and concrete.
