rotted sill on bay window

Old 08-11-18, 05:01 PM
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rotted sill on bay window

So I have this bay window in my new home that clearly had some damage when we bought the place - there was a rotted section that they had stuffed dryer sheets into and then covered with duct tape. We pulled out most of the rotted part today. There's some sort of metal flashing tucked under it that seems to have done more harm than good - it looks like water was getting in there and rotting the bottom of the sill. The metal itself is also pretty damaged. I'm just wondering if anyone has any suggestions about how to fix this properly. Name:  IMG_20180811_154012148[1].jpg
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Thanks in advance

ETA: we haven't seen any sign of water coming in during rain storms since we bought the house. The previous owners seem to have applied some sort of tape/flashing around the underside of the window - don't know if that fixed it.

Last edited by handy1018; 08-11-18 at 05:07 PM. Reason: forgot a detail
Old 08-12-18, 02:52 AM
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The inside fix is pretty straight forward, remove the bad and replace with new.
What do you mean by the underside of the window being repaired to keep out water? Water doesn't generally run up hill. Pics of the outside would be nice.
Old 08-12-18, 04:23 AM
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I stating the obvious but water is getting to the wood and it's coming from the outside.

Something with the flashing on the outside is not correct and that is going to be the tough part to identify.

Any chance you can identify the make of the window? That may allow some search for installation instructions to see what is missing or incorrectly installed!
Old 08-12-18, 06:04 AM
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This it not necessarily from rainwater or anything having to do with the flashing... although it could be. Pictures from the outside would help. Condensation has probably been forming in the hollow mullion channel between the corner windows, likely due to a poor air seal. If it's dry in the summer and wet in the winter, it's probably from condensation.

I don't really have any good suggestions on fixing it... I have probably installed a hundred of them, but they are prebuilt units that come with the head and seat already installed and you just set them in the opening and trim them inside and out. That wood goes underneath all the windows and helps hold them together. There is also often a cable in the corner to help support the weight of the bay... if the plywood is gone or rotted, that cable is slack and the window can sag.

I suppose at this point you would have to piece in some plywood, laying it in a thick bed of construction adhesive... then it would be a good idea to make a new seat out of 3/4" to lay over the top to hide the repair.
Old 08-12-18, 10:05 AM
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outside pics

Thanks everyone for your thoughts, they are very helpful.
I'm attaching some pictures of the outside so you can see the "repair". I took a shot of the underside of the corner that rotted, as well as one of the top.
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@marq1 It is flashed identically to many other houses on my street, though I know that doesn't mean it's right. I don't see any indication of the manufacturer. It seems to me like the theory behind the flashing is that water will run down the front of the window and drip off the bottom edge, but I was thinking maybe it had run back under the window and wicked in through some small holes formed over time.

@xsleeper I haven't owned it through a winter yet, so I don't know if it's wet in winter or not. I guess it could also be that they left the window open - the hand crank is not working properly. Is there any way to combat the condensation problem you mentioned? Would it make sense to try drilling a weep hole at the bottom of the channel? It think the middle window has a couple at the bottom that were manufactured in.

You can't see it in the picture, but there is a post protruding from the bottom of the vertical corner channel that I think belongs in that little hole. It's rigid but I can move it around a bit, and it has what I think is a big washer at the bottom - could this be for the cable you were talking about, xsleeper? I might be able to cut a channel in the replacement wood to slide that through.

Thanks for all your thoughts.
Old 08-12-18, 10:13 AM
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Yeah, the outside is definitely leaking like marq1 said. (Probably not condensation now that we can see the outside) Everything needs maintenance and that clearly has gotten missed for many years now. About all you can do with that on the outside is keep it caulked up. OSI Quad is about the best thing to use there. Unfortunately that's just a low quality bay window that isn't lasting as long as one would have hoped... not really anything the installer did wrong.

yes, the washer is the bottom of the cable.

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