Help: Bay Window Problem (Leak?)

Hello,

We are having a major problem with two bay windows we had installed in July of 2007. Last February (2008) stains suddenly appeared on the seat of the bay window (note: absolutely no stains on the top). If you look at the stain patterns, some stains seem to come from absolutely nowhere. The manufacturer and the dealer/installer have been of very little assistance, and I need some help identifying what this could be caused by.

Can someone please look at the following pictures and provide some feedback? There are two sets of pictures: dining room and living-room. I have included some close-ups for the living-room bay window (last two pictures, at the bottom of this post).

DINING ROOM:








LIVING ROOM:
















Any help would be greatly appreciated!

 

You definitely have water penetrating your bay windows How often does this occur? All the time, heavy rain? Is there any kind of an overhang on the bay roof? If not, rain water will run right down the face of your glass and is finding a way in. If your contractor won't come back, I would examine the exterior of the units and try to identify any places that could possibly leak and caulk anything that looks suspicious.

 

Well, the one close up of the corner with moisture up on the white surface certainly looks like condensation. I didn’t see where you were, cold country or warm? But you stated last Feb the problems started and now it’s Jan. Sure looks like condensation above or within the bay window. Somewhere, warm moist air is leaking into where it is contacting cold surfaces, condensing out as moisture or frost and then leaking down to the bottom seat area where you see the staining.

Leaks should leak all of the time. Condensation will only happen in the colder weather.
If it’s condensation, then the installation of the window needs to be checked and corrected with proper sealing and insulation.

Bud

 

I think Bud's got the right idea - how well insulated is the seatboard? Bay windows (by design) are just begging for problems both above and below, but i think this is a case of a cold seat.

Is the underneath flat or does it angle back to the house?

 

That first picture is showing a lot of water damage. Unless this is an incredibly cheap window unit with no insulation at all beneath, it shouldn't condensate that much. Nothing I use would do that. Also, it appears that you have unfinished oak seat boards which is making things look even worse. Should clean them up and get some poly on.

 

Thanks for your reply, Bud. I am in a 'cold' area (Toronto, Canada). If it is condensation that is causing the staining, how should I check for the source? In case it helps, last winter (when most of the damage occurred) we did not have a humidifier installed on the furnace, and the inside humidity levels were really low - does this impact your diagnosis?

The dealer that installed the windows claims it's ice/water backup, but I don't buy that (there is no staining on the top of the bay window, and the roof is only 2yrs old with plenty of ice/water shielding installed)...

Thanks -

 

During installation, I noticed that the installer fed quite a few boards of flat, hard insulation under the seat. I believe he also used the spray foam after that. Is there any way to test if the cold-seat is the cause of this problem?

 

Hi Craig,

I only notice new staining during cold weather. The roof of the bay is built-into the soffits, the roof is relatively new (2yr), and the soffits/facsia/freezeboards were all replaced at the time of window installation (across the whole front of the house).

The bay sits on a stone sill. Is there anyway that the sill could be getting soaked / freeze / thaw, and then the moisture is wicking-up into the wooden base?

-Scott

 

Hi, I'm inclined to agree with these other guys that your problem is primarily a condensation issue. However, I would still go outside when it's a little warmer and caulk anything that looks like it might need it, seams between the windows, etc.
You really should protect those nice oak seat boards before it's too late. Oak doesn't handle water well at all and tends to turn black. Use some light sandpaper to remove the staining and put a couple coats of polyurethane on them. This way even if your windows continue to do whatever it is they are doing, at least your seats aren't getting wrecked.

 

“I only notice new staining during cold weather.” Then it definitely is a condensation problem.

“The roof of the bay is built-into the soffits” When they are built into the soffits, there is rarely anything covering the top. They usually just stuff them with fiberglass insulation, which will not stop air flow. The stack effect of air rising into the attic can be pulling moist air into the structure of the window and above, depositing it’s moisture, which then leaks down to where you see it. Check what you can see from the attic, if possible, to confirm if it is open or closed and not just covered with insulation.

If the bay juts out beyond the sill on the bottom, then you may have to address the air sealing and insulation below as well.
Bud