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Q. What's the right way to flash an exterior masonry chimney to the wall of the house?

A.Fred Seifert responds: I bend an F-shaped piece of flashing that catches the ends of the bricks where they meet the house (see sketch). I use copper, lead-coated copper, or aluminum and bend the flashing in long pieces on an 8-foot brake. We nail the flashing to the sheathing over the housewrap, then use a flashing tape to seal the outside leg of the flashing to the wrap. The mason spaces the brick away from the flashing so that any water that gets in can drain down and out the bottom through metal weep channels embedded in the mortar under the first course of brick.


Depending on the height of the house, it may take three or more lengths of flashing to reach the roofline. At the joints, I prefer to butt the pieces rather than overlap them, because it looks better. To maintain a tight seam on the exposed kick where the flashing meets the brick, I run a spline several inches long inside the bend to span the joint.

Having passed down the family business, Fred Seifert, Sr., works for his sons, Fred and John, at Seifert Brothers Construction in Mattituck, N.Y.