Hi Everyone,

I have an uncommon bay window setup at one corner of my home. I have a double bay window set (one on the south side, one on the west) on my main floor and another set on the top floor, for a total of 4 bays. The two sets on a given side form a "tower" on the outside from the main floor to the top floor.

I had all windows, siding, capping, etc replaced a few years ago, however, at least one "tower set" appears to be leaking. When it rains, it's wet at the main floor windows (visible water stains) and water is getting all the way down to the basement floor creating a large puddle, which appears to come from above the door (always a large puddle on top of the door behind the trim).

After a lot of testing with a garden hose (not just the windows, but above the basement door, a stove vent nearby, etc) which my contractor told me was an invalid test (it's a walkout, so the windows are high and not getting blasted - I can't even reach the top of the siding) it appears to be leaking where the siding is between the windows, though there's probably more than one issue.

I've attached some pictures with brief descriptions of possible issues. I took a look at a neighbour's (who told me his don't leak - no pictures attached of that setup though) and they were done a little differently there.

I'm looking for some advice on best practices for this kind of setup, and I've listed some of the things that I believe are issues. Any and all feedback is appreciated. The leaks have been driving me a little crazy!

• It seems like there's too much reliance on caulking and not enough flashing - more on this below
• The very top of the bay stack is protruding farther than the fascia. If there is an issue with the roof and the water goes down the fascia instead of the gutter, it could enter the house
• The J-trim at the bottom of the siding is acting as a gutter and catching water. This was partially addressed in a prior service visit but I believe is still an issue.
• The capping below the top-floor window is either level or slightly angled toward the windows. It would be better for this to be definitively angled away from the windows.
• Compared to my neighbour, there appears to be less use of flashing. For example, they have some flashing that I suspect is L-shaped and goes behind the siding/plywood between the bays and then angled on-top of the capping/window, so that water sheds away and if water were to get behind the siding, it still has a chance to drain out.
• For the top J-trim piece, a piece of flashing could go on top there which could go behind the capping. There seems to just be caulking between the J-trim and capping, instead of flashing on-top of it to guide water away when the caulking fails.
• My neighbour's siding between the bays goes much lower/higher than mine, whereas mine has more capping/joints. This seems like a good idea, so that the J-trim could be infront of the capping, so when water gets to the lower J-trim from the siding, it would have a harder time getting behind the capping and into the home/between the windows. I suspect it may be possible to eliminate this J-trim completely
• My neighbour's siding is aluminum (mine is vinyl), and it looks like they folded it over the plywood, so that the siding joint does not line up with the plywood joint underneath. This also avoids joining the siding pieces at an angle
• There are some icicles on the west side bay, particularly at the bottom J-trim, so I think water is not draining away properly or fast enough

Would appreciate any/all advice or feedback, even if it's that I'm just out to lunch here!

Thanks,

Jim