Is it necessary to make movement joints in metal flashings line up with the expansion joints in masonry veneer walls?
In most cases, I do not recommend installing movement joints in metal flashings. There will, of course, have to be lap joints between sections; however, even these lap joints I do not recommend lining up with expansion joints. Over time, the sealant in the expansion joint in the masonry veneer wall will fail and need to be replaced. Before the sealant is replaced, however, a considerable volume of water will flow into this joint during rainstorms. If the lap joint in the flashing lines up with the brick expansion joint, water leaking at the expansion joint will flow over the joint in the flashing. If this joint is not perfectly sealed, there is a good chance that it will leak.
The metal flashing should not prevent the expansion joint from operating properly. The masonry can move laterally by sliding on the top surface of this flashing. Therefore, it is not necessary for these joints to line up.