Homeowners paned by persistent window leak

DEAR BARRY: Last winter, one of our windows leaked for the third year in a row. We tried caulking and even installed an awning over the window: all to no avail. Each time it rains, water drips from the upper edge of the window frame, damaging the paint on the sill and wall. The handymen we've called give no guarantee that they can solve the problem. How can we identify the origin of this leak and get it to stop? — Gannon DEAR GANNON: Sources of window leakage can confound the most dogged house detectives, but for every problem there is a solution awaiting discovery by those of unyielding determination. So let's consider three possible causes:

1. Some windows leak as a result of faulty design. These can usually be identified by a qualified window installer. If you know of an experienced and knowledgeable glazier in your area, have that person take a look.

2. Some windows leak because of faulty installation, usually with regard to the flashing. Flashing is the waterproof membrane that is applied to the window frame before installing the exterior siding. When this is the problem, repair can be costly, because some of the siding may need to be removed.

3. With stucco houses, leaking can occur because of direct water penetration through the stucco itself, especially if the flashing is not properly installed. A common solution for this type of leakage is the application of elastomeric paint. This is a rubberized finish that will thoroughly seal the wall surface with an impermeable membrane.

Before proceeding with attempted repairs, try water-testing the area around your window with a garden hose. This may help to identify precisely where the leakage is taking place.