We were painting our ceilings and removed the register for the central heating system.

The hole is roughly cut. And I can see right through to the attic along the edges between the duct and the ceiling.

enter image description here

We have a 1939 house and most likely there is lead within the various layers in the ceiling exposed by the hole that was cut.

Also, our attic is really dusty and I don't want any dust to potentially be blown into the room.

I want to seal the raw edges of the ceiling AND I want to fill the gaps between the duct and the ceiling.

How would I go about doing this?

Update: repaired

I took Dan D.'s advice and sealed with joint compound and followed up with UL181 metal tape.

sealed with joint compound followed up with UL181 metal tape

What I'll probably also do is to go into the attic and seal around the attic floor/rigid duct interface with caulk or expanding foam.

1 Answer 1


I would use drywall compound and fill in between the wall and the duct. And then I would tape using a UL181 tape (I like foil mastic) over the inside edge of the duct and the wall. Apply the tape flat and rub it smooth. The tape will be covered by the register.

Using UL181 tape to seal the duct to the ceiling membrane really should be standard.

  • Use the tape on the surface of the ceiling and the inside surface of the duct? Use it to cover the joint compound and the duct?
    – milesmeow
    Commented Nov 30, 2016 at 9:09
  • Can some joint compound go on the inside of the duct so that it's a complete seal before we use the tape?
    – milesmeow
    Commented Nov 30, 2016 at 16:06
  • Can I use expanding foam from the attic to seal from up there also or instead of the joint compound? I would still use the tape.
    – milesmeow
    Commented Nov 30, 2016 at 16:09
  • Does it matter if there is nothing in the attic that is holding down the duct. Literally the two screws of the register is holding down the duct.
    – milesmeow
    Commented Dec 3, 2016 at 6:03
  • Check out the finished repair pictures Dan D.
    – milesmeow
    Commented Dec 6, 2016 at 7:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.