Our house was built in 2016, shortly after moving in we noticed that all of our windows on the main floor leaked. The builder came, did something (I wasn't home), and all but one stopped leaking. It didn't leak often, so like a responsible homeowner, I am just getting to fixing it.

I inspected the leaking window and noticed there were gaps in the caulk between the board trim (see image below) and the window, so I re-caulked all the windows. Recently it rained, and now two windows leak (the one, and an additional one).

Window Outside In the picture, we have vinyl siding, j-channel, board trim, window. I caulked between the board and the window. I am wondering if it shouldn't be caulked because the water has no were to escape if it gets behind the j-channel. thoughts?

enter image description here Here is a picture of the water damage if it helps, the water oddly enough leaks on the same corner of all the windows, its always the left bottom corner.

Here are some additional pictures. Upper right corner enter image description here

  • Hello, and welcome to Home Improvement. Have you noticed what makes it leak more or less (e.g. wind while rain)? And, you should probably take our tour so you'll know how best to participate here. Nov 9, 2019 at 21:12
  • As Machavity implied, caulking outside isn't the way to fix this (nor is caulking inside, per your comment above). If the leaks are coming through at the interior trim, I'd be pulling it and foaming around the windows. Please tell us where exactly you detect leaks.
    – isherwood
    Dec 7, 2020 at 19:13

1 Answer 1


[I] noticed there were gaps in the caulk between the board trim (see image below) and the window, so I re-caulked all the windows

Gaps between the board and trim are normal. The standard way this is done is you have your siding in layers

  • Siding board (OSB)
  • House wrap (plastic or tar paper)
  • Window tar flashing (bottom)
  • Window
  • Tar flashing (sides and top, hopefully nested just under the wrap)
  • Siding

Caulk can improve on this some, but properly installed windows like this should not need much, if any, caulk. Any water that gets behind your siding should be channeled down to the ground.

My bet is the window was installed incorrectly. A common area builders like to cheat on is wrapping the house wrap over the edges of the sill. That can create a pathway for water to penetrate the house. Caulk can't fix that either, since water is getting behind your siding.

Your best bet is to pull the siding off next to the window and make sure it's layered properly. Check the bottom corners if you can, since you typically need extra wrap there.

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