I have an exterior door (~7 y/old) and the top frame is rotting. The door is on the SE side of house and gets almost no rain (weather comes from west normally). There is no screen door. The door is on the first floor, at my "workshop" room which is also next to the garage. So it is not, as far as I can tell, rotting from exterior moisture. It is from interior moisture or condensation. I have poked thru the wood and touched the insulation in the space and it is damp. The workshop room, and the garage which it is open to, has a relatively high humidity most of the time, I think because the water softener system is in the garage and the salt box isn't hermitically sealed. The humidity guage (in garage and workshop) is nearly always above 60%. The workshop room has only panelling on the walls (painted) not drywall. I suspect that the humid air is getting thru panel gaps, going into the gap around the door, and meeting a cold piece of wood (as it is exposed) in the winter, making condensation inside.

What would be a good preventative to seal up the room and stop the condensation? Should I remove all/some of the panelling around the door on the inside and replace with drywall? Should I apply a layer of tyvek/house wrap under the panelling? How well sealed would that need to be to the studs underneath? Other options? Thanks.

  • Are there any opening anywhere above the door in question?
    – JACK
    Jul 15, 2022 at 17:31
  • There is no window or other opening in the house there, above this door. On this wall there is only this door and the main car garage door next to it a couple feet away. Jul 15, 2022 at 18:46
  • Solution was it seems there was caulk missing and even a small water intrusion probably never could dry out, the insulation was packed in so tight. Replaced wood with plastic plank and fixed caulking above flange area. Jul 20, 2022 at 13:22

1 Answer 1


Wet insulation is never a good sign.

I would open up the paneling to see how bad it is, and keep removing insulation until there is no more moisture. You're going to have to do this anyway to add a proper vapor barrier.

At that point, you should be able to see where the water is coming from, and you may be surprised that there is a leak in the roof, siding, pipe, or who knows what. You may have mold to deal with as well.

Sealed inside a wall with no escape via evaporation, it doesn't take much of a leak at all to accumulate water.

Once you're in that far, you can evaluate what needs to be done to add or replace a vapor barrier. Would adding some ventilation to the room be an option as well?

  • 1
    Good answer. Note that leaks in the roof can often travel quite a way from their source. Jul 15, 2022 at 19:23

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