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Leak at top of Window

I have rain leaking into the top of my window. I cut away some drywall to look up into the wall and it appears that the water may be running down the outside of the builders felt, which terminates at the top of the window, then, instead of being diverted around the window and down to the weep holes in the brick facing, it has found a seam where the drywall meets the window frame and is running into the house there. Is this a flashing problem? How can I repair it? The house is 13 years old. This is the only window that has this problem.

Re: Leak at top of Window

Yes, it DOES sound a lot like a flashing problem.

What kind of exterior siding do you have???

Brick, vinyl, aluminum, clapboard, wood shake???

There should some sort of horizontal wood or metal piece of flashing at a 45 degree angle, slightly wider than the window, resting across the width of the window along the top, to divert the water out & away from the window top as it comes down the siding of the building (see irc website below).

For aluminum & vinyl siding it's usually an aluminum drip cap, or sometimes a J-strip.

It goes up & under the siding & under the building paper or sheathing membrane (see websites below) that should be installed when the window is installed.

For brick or stone sidings, or older homes, it's often an angled piece of cedar or even a piece of zinc.

If it appears something's missing, check the other windows for comparison.

At the IRC site below, scroll down to the last diagram to view how the sheathing membrane should surround the window & sheathing to keep water out, and how the drip cap should fit under the membrane to divert any water that may work its way in near the top of the window.

The ehow site shows how you can easily make a piece of drip cap flashing from a random piece of aluminum hanging around the house; otherwise, you can buy a piece at the big box stores.

Run some silicone caulk or caulking designed for exterior windows & doors to seal any small holes, after the new flashing is installed.

Test the effectiveness of the new window flashing by playing the garden hose above it to check for leaks.

Once the window tests ok for no leaks, you will have to use a stain sealer on the inside drywall stains before you repaint, otherwise the water stain will bleed thru if you just paint over.

Or you can cut out the stained portions & install new drywall pieces, tape & scrape.


Re: Leak at top of Window

Thank you JacktheShack. I checked and I do see a flat piece of metal running across the width of the top of the window on the outside. It doesn't appear to be angled to the eye though, and when I cut away the drywall on the inside, I don't see that it comes in as far as the edge of the window frame where the black felt piece terminates. I have brick siding by the way. I am considering replacing this window. Could this situation be remedied with some additional flashing and/or sheathing when the window is replaced? In the absence of replacing the window, is there some other solution?


Re: Leak at top of Window

I would suggest you hold off with the new window until you locate the leak.

You could end up installing the new window & still end up with a leak.

If you want to attempt to fix this yourself, inspect the exterior top of the window to make sure the drip cap flashing overlaps the window.

Caulk any suspicious areas that look like they may let in water.

Closely inspect the area above the window for any hairline cracks in the brick exterior at the masonry joints.

The leak may be coming from a hairline crack masonry joint above the window.

Caulk any suspicious hairline cracks.

Use the garden hose to see if you've found the leak.

Re: Leak at top of Window

I have inspected all around the window and everything appears sound. I can see where the previous homeowner caulked about everything in site, presumably to fix this problem, which they then left undisclosed at the time of sale.

I may need a professional to help me on this. Who would I call for such a thing?

Re: Leak at top of Window

Consult the Yellow Pages under "Windows-Installation", and also under "Contractors".

Re: Leak at top of Window


Is there a door or window directly above this leaking window?

If so, the leak could be originating up there......either thru the sill of the window or the threshold of the door. If there's a leak up there, it could/would track down the studs or sheathing and emerge where you see water entering. Look for a small crack where the side jambs meet the sill or threshold.

It is also possible that the leak is orginating at a fault in the roofing somewhere above this window.

Re: Leak at top of Window

As I stated above, we had the same problem. Almost flat window sills. The downstairs widow leaked at the top. It turn out the rain on the sill upstairs was being blown back under the window sash , in between the sill and the stoop and down the back of the sill. to solve the problem I opened the upstairs window and caulked between the stoop and the sill.

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