When I lay brick on flashing on top of a shelf angle, should I put mortar under the brick or should I lay the brick dry?
Lay the brick dry on top of the flashing. This lets water drain from the wall better, because water can exit anywhere along the wall between the brick and the flashing (not only at weep holes). Mortar laid on the flashing also can block weep holes. Laying brick dry on the flashing keeps the thickness of the joint closer to the thickness of other bed joints in the wall. With a 3/8-inch-thick shelf angle and a compression pad under the angle, the thickness of the joint is 5/8 inch. Placing mortar on the flashing would make it even thicker, creating a noticeably extrawide joint. Norbert V. Krogstad is a senior engineer at Wiss, Janney, Elstner Associates, Inc., Northbrook, Illinois.