I installed a Pella Proline double hung two windows wide each 33"x57", per the manufacutures installation method. This past weekend we had a big northeaster storm, high winds and torrential downpours, which caused the window to leak at the bottom. However, the water was not visiblly seen flowing out. The drywall is wet at the bottom of the window and water has pooled out onto the floor. So it sounds like water is leaking inwards through the window but inside the wall and out on the floor. I'm going to remove the bottom interior trim, and section of drywall. However, I don't know how to fix this issue. I flashed the whole rough opening before I installed the window and added flashing around the nailing flange. Any suggestion on what to look for and do?


Frank

 

...per the manufacutures installation method...

This would mean that you should have had building paper on the wall prior to installing the window. You would also cut the building paper up and out at a 45 degree angle to create a 6" flap on top of the rough opening. This flap would be folded up out of the way when the window is installed. After the window is installed, Pella flashing tape would cover the nailing fin on the sides first, then when you apply it on top, it would be stuck to the sheathing. The building paper flap would then be folded down and it would be either completely taped or skip taped (depending on if you are trying to make the building paper air-tight or not).

If you are using felt (tar paper) as your building paper, Pella's flashing tape does not stick to tar paper for very long.

You also should have paid special attention to the 4 corners of the window to ensure that the flexible corners were properly stretched, and reinforced them with more Pella flashing tape.

The window should also have a drip cap installed over the top nailing fin to protect the center mullion (the seam between the 2 windows) from water infiltration.

It's possible that you could have done everything right and water is coming in above the window in question and getting behind the building paper. But I would assume that one of the steps above was either overlooked or done improperly.

 

Okay my mistake.
The windows are being installed on existing siding; this is not a new construction house just new construction windows, the house was built in '77-78 time.
I undertstand your first paragraph. This how I installed the windows as close as possible to the instruction.
1. Removed the existing old window
2. Cleaned up area, and the applied 18" wide buytl tape around the rough opening. Pells says to aplly to top and bottom section only with 6 inches going on the sides. I added buytl tape all raound perimeter.
3. tuck bottom and both sides of felt paper back in rough opening
4. Installed window. Used stainless steel wood screws instead of nail on the nailing flange.
5. Flashed both sides bottom and top and added 45 degree flashing as well.
6. folded down top felt paper and added flashing.
7. install neve rott wood trim.

I'm going to look at the following when it stops raining.
I did not install a top metal drip edge, because I talked to at least pella engineer a few times, and was told it is not required.

I think my problem might be either the 4 corners are not flashed below properly or the top flashing is losing its adhesion ability and water is getting behind it. However, this window did not leak in the 2 years since its been up. The rain storm was pretty bad with 60 mph wind gust. Do you think the windows is water damaged?

Thanks
Frank

 

Sounds good. Usually the problem you have when you are remodelling, not removing a lot of siding, is that you can't flash the top very well, getting the new felt paper underneath the existing felt paper is critical.

The only question I would have is 1). what sort of siding you currently have, and 2). what's above the leaking window? i.e. soffit, 2nd story windows, etc.

You are right about that much rain and wind causing never-before-seen problems. But it does indicate a problem that needs to be addressed. Even heavy rains should not cause leaks inside the home.

I doubt that the windows are damaged at all. They will dry out and be fine. If the window is surrounded by fiberglass, that might be a problem. Wet fiberglass doesn't dry quickly- you might want to remove the interior trim and remove any wet insulation to facilitate drying. If it doesn't dry quickly you may get a mold problem.

 

Well I found out where the water in migrating into the house. Last night, after work, I removed the bottom interior trim and the dry wall was wet. I cut a 1 ft wide x 4 ft long section out and the sheathing was wet as well looking from the inside of the house. So, I removed the window screens and stuck my head out and I saw that the felt paper has deteriorated (at the bottom of the rough opening mid-section) to the point that the sheathing is exposed and water is migrating at that point. So a quick temporary fix, until it stops raining, was to add so buytl tape as flashing on the bottom of the window. It seemed to stop the water from coming into the house.

The problem(s) when I'm replacing windows, on existing siding is two:
1. I can only cut back the siding far enough (without exposing to much of the house) for exterior trim. So I'm not able to flash much wider than the nailing flange.
2. The felt paper usually tears when I'm cutting the siding so I have to at buytl tape all aroung the rough opening in place of the felt paper. So this is acting like the house wrap.
3. The siding is a composite material like particale board, when it gets wet it swells and then when it drys you can crumble it in your hand. Why, because some previous owner placed vynal siding on top of the exiting siding and did not add insulation board.

My goal is to replace all the windows and then have the existing two layers siding removed and then have new siding installed properly. In answer to your question, the siding is similar to a MDF composite material and there is nothing above the windows except a soffit

Frank