Question: How should you terminate masonry through-wall flashing at door jambs and at first floor windows that extend to the base of the masonry wall and are recessed from the face of the wall?
I know that end dams are recommended; however, how can end dams be installed in these cases when the brick masonry is typically returned beyond the face of the window at the jambs? Should the end dam be placed in the first mortar joint in front of the window or door? In this case, what will happen to any leakage that may occur in the space between the end dam and the face of the window or door?
Answer: In locations where the doors or windows are recessed, I typically recommend using a three-sided end dam. The three-sided upturned leg of the end dam should return out beyond the exterior face of the window or door. Water that reaches the flashing in this location cannot leak into the interior; it will be diverted to the exterior in front of the perimeter sealant joint for the window or door.
The three-sided end dam should extend far enough beyond the face of the window or door frame so that the perimeter sealant joint can be bonded to the exterior face of the flashing end dam. It is important that this flashing end dam be installed tight to the face of the masonry so that there is not a significant gap that would be unsightly and make the installation of the perimeter sealant joint difficult.