How to Flash a Roof to Masonry Walls

Flash a brick, stone or stucco wall during construction as you would a wood-sided wall. Nail the flashing to the wall with galvanized shingle nails and a hammer; never nail into the roof surface. Lay brick or stone facade over the flashing or cover the wall with stucco down to the roof level then install shingles over the roof side of the flashing.

Use a double flashing technique, called counter-flashing, when installing flashing against a brick or stone facade already in place. Put flashing down with one side on the roof, the other up the facade. Nail it in place with masonry nails driven into the mortar joints or brick or stone face.

Add counter-flashing by cutting into the mortar joints with a circular saw fitted with a masonry blade then sliding the top of another layer of flashing into the joints. Adjust the depth of the saw cut to fit the width of the flashing. Put the other side of this counter-flashing down the wall to cover the top of the base flashing. Make sure it has a lip at the bottom of the roof side to direct water away from the wall.

Install Z-bar flashing on finished stucco walls. Cut through the stucco 5-1/2 inches above the roof and remove it down to the house wrap. Nail a 1-by-6 blocking board to the studs in the wall. Slide metal weep edge flashing behind the stucco face and under the cut bottom. Slip Z-bar flashing behind the weep edge, over the top of the board and down the face to just above the shingles. Put regular 90-degree roof flashing behind the Z-bar and out over the roof to be covered by shingles.