This Digest discusses the nature of wood shrinkage and its effect on the performance of certain building assemblies. Wood shrinkage can cause many problems, from nail popping to truss uplift. Using lumber whose moisture content does not exceed 19 percent should significantly reduce the incidence of most of these problems. It is possible to allow for truss uplift by using floating corners that will permit the ceiling to flex without tearing away from partitions. If floating corners are not used, corrective action is normally limited to concealing the damage by means of moldings or suspended ceilings.