Question: How can I tie the top of a concrete block backup wall for lateral loads and still permit the floor structure to deflect without applying load to the top of the concrete block wall?

Several ways to provide lateral support to the top of block backup walls are shown in NCMA-TEK 111. Where the floor deflections are to be isolated from the walls, a combination of angles on the front and back faces of the wall can be used. Details 5 and 6 from this technical note illustrating this condition are shown.Consult the NCMA publication "Architectural and Engineering Concrete Masonry Details for Building Construction" for further information.Many other details likely can be developed. The details should be carefully designed, however, to provide adequate lateral support and still permit the structure to move freely.