How to Cap Flash a Recessed Round Window in a Stucco Wall

Cap or head flashing with a waterproof substance such as metal or plastic is intended to direct dripping water away from vulnerable points at which it might get into a structure. Any window or door is such a point, and a window in a stucco wall can require special attention because stucco is a particularly porous material that tends to soak up water. While a recessed window is somewhat protected from the elements, a round window requires careful flashing to direct water away from it.

Self-adhesive flashing tape or flexible membrane flashing
Tin snips, metal shears or heavy scissors
Exterior-grade sealant
Small J-roller

Instructions

- 1
  Select flashing tape or flexible membrane appropriate to the size of your window. It comes in widths of 4, 6 and 9 inches.
- 2
  With the window frame exposed, begin at the widest point of one side of the window where the curve of the lower half of the circle begins. Cut short pieces of flashing tape and attach them smoothly and securely to the window header, being careful to overlap each piece on the last, until you have formed a curve matching that of the window and carried all the way to the opposite wide point.
- 3
  If you elect to use a flexible membrane, apply it in this same curve and smooth it seamlessly into place, using your hands and, if necessary, a small J-roller.
- 4
  If you feel extra protection is needed, take a paper pattern of your window to a roofer or a sheet metal worker and have a drip cap made to fit the curve. The ends of this cap should be flared away from the curve by about 1 inch to carry any water well away from the window.
- 5
  Attach this cap above the flashing with a continuous bead of exterior-grade sealant only. Do not use nails or screws, as any holes made in the cap will provide entry ports for dripping water. Be sure that the top edge of the cap is fully sealed.

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