I am a condo owner in a building that is structurally independent but abuts directly against another building. As a result the 2 buildings move somewhat as they settle or have changes in temperature.

Unfortunately there is also a gap on one side of the building.

This is the exterior of the building: exterior of building

I also took photos from within the back wall of my apartment: photo of interior of back wall showing sunlight from .5" gap

How can I seal this gap? Should I use something like butyl flashing tape to seal our building to theirs and then replace the wood trim back over it? Or should I just spray foam it and hope that the buildings don't move too much?

  • 2
    What issue or problem are you trying to solve? May 24, 2021 at 14:23
  • @DavidSupportsMonica My back office wall is extremely drafted because it is uninsulated and there is that roughly 1/4" gap exposing the empty wall to the outside. Additionally when the wind is extremely gusty the wall "inflates" and rattles because the wind is putting direct pressure on interior drywall. My hope plan is to take down the drywall, seal the gap, insulate the wall and close it back up but I don't know what to buy to attach my building to the neighbors' building. I worry that simple closed cell spray foam won't be flexible enough to handle the buildings shifting. May 24, 2021 at 17:35


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