Ask the pros-August 2010

By Reggie Bullard
  Window leaks due to no flashing.

              Window flashing detail
Not sure how to solve this problem...

1936 stucco house. Old metal casement windows with a gutter above and no eave or overhang. The "bay" windows leak all the time when the rain blows sideways or the gutter overflows.

We will replace the 2" downspout with a 3" down spout - but if the gutter still backs up, which I'm afraid it will, i wanted another option.

I was thinking of some type of drip cap applied over the window but I want to just apply it on top of the stucco and not penetrate it due to possible leaking and expense of tearing out the stucco.

The window is approx 36" wide so the piece might need to be 40" wide or so. Are there any adhesives or mortar that could be used to just add stucco and fashion a cap that sticks out far enough - maybe 5"-6"? I was thinking of using terra cotta tile (to match the roof) on top of this stucco or mortar shape. It just needs to be straight above the window. I could have a clay piece made and high fired to create an edge that will make sure the water drips down and does not run back to the wall. I just am not sure an adhesive would be strong enough?

Any ideas or info on weight it would hold?

Water will penetrate stucco, even if it has been painted. The only way you can be assured that your window won't leak is to cut off the stucco above the window,
nail your window cap to the sheathing over the window. Note how the window cap angles down from the back to the front deflecting water away from the building. I have
seen window cap angled backwards, that is toward the building. Water will run back behind the stucco and down the sides if the flashing is put on this way.

Note also how a gob of caulking over the top of the window would impede water flow.

Flashing isn't require if the windows are up high, such as on the second floor, and there is a large eave, or roof overhang.

Unfortunately, a patch always tends to show, even if painted, and color work is practically impossible to match. We do a lot of this patching over windows and around
windows for new window installation, and generally the stucco gets painted.
We hid a patch recently by covering the patch with a stucco band. May a trim made from another material such as your terra cotta idea would be the ticket.

This should solve your leak.

A window leak at the top can damage the stucco or the framing under the window.
Water will run down the sides until it hits the framing under the window. I have patched under windows on old houses for years, and usually rusted out flashing, lack of flashing,
a rotted window sill is the cause of the damage.

Poorly installed window flashing
Poorly installed window flashing.
Note how the top flashing was put on first and the side second, allowing water to run down into the side flashing.

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