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Drywalling over ductwork - insulate or air gap?

24194 Views 9 Replies 4 Participants Last post by  ToolSeeker
I have overhead duct in a closet and I'm getting ready to cover it in drywall. I have a couple of questions:

Should I put insulation between the drywall and the ductwork? Or just leave an air gap? (the drywall will be directly below the duct)

If I use an air gap, what is the minimum spacing I can use?

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Forgot to mention this is in a basement. I saw some places that said it was okay to place the drywall against the ductwork but I can't help but think that you need room for expansion and contraction. I'm not sure if condensation will occur in the summer since the basement tends to be cooler than the rest of the house.

I had a drywall guy here the other day and he mentioned that about half of his work was repairing drywall that was placed against ductwork that eventually crumbled.
I'd say frame a bulkhead around the ductwork and then attach dry wall to that. I doubt you would want to use screws, nails, or glue directly to the ductwork.
I'll have to do a frame, my question is if I should place insulation between the duct and drywall or just leave an air gap.

ETA: Just realized I didn't even mention that in my first post...whoops! Yes I'm building a frame around the duct, I just want to know how to space everything out before I build the frame.
this sould give you some ideas.

Around my neck of the woods we don’t put installation around enclosed duct work.
Gotcha. No I wouldn't put insulation between the ductwork and the drywall.
Those are good pics of framing and I appreciate the help. My problem is this ductwork is in my closet ceiling, and the bottom surface of the duct is almost parallel to the header for the closet door. The closet header height is already short (76" high - it's an older house) and the drywall that I will place under the duct will meet up with the closet header.

So if build a large frame around the duct with 2x4's, I will have to lower an already low closet by another 2" or more to meet up with that drywall. Since you mentioned insulation isn't really needed, I'd like to know the minimum air gap between the duct and drywall do I don't have to lower the closet by much. If I can get by with 1/2" gap that would be nice.

(And I can't raise the closet door. The header is attached to the bottom of the main support joist and I don't want to cut into that)

ETA: Don't know if my descriptions are making sense or not. I'd post pics...if I could find my camera!
You can build your frame using 1 x 2 strapping leaving a ½’’ gap between the duct work. Also you can use ¼’’ or ½’’ drywall sheets if this will help your situation.
You can build your frame using 1 x 2 strapping leaving a ½’’ gap between the duct work. Also you can use ¼’’ or ½’’ drywall sheets if this will help your situation.
That would be perfect. :thumbsup:
I guess i am the minority here but I would go to the home store and buy some thin styrofoam sheets and insulate around the duct then frame it. Any uninsulated duct work is a heat loss, even if this is a small area it is a good place to start. Also when you are framing be careful not to run any screws into the duct.
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