Is it ok to apply duct selant inside return vent box?


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Old 10-20-22, 05:03 PM
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Is it ok to apply duct selant inside return vent box?

Hello. I have a 12x24 return vent box 14" deep that is installed to the wall on top of the stairwell. The back of that wall is unconditioned attic space with no access. I want to seal the seams on this box to prevent any air being pulled from the unconditioned space. Will there be any issues (like air quality, code violation etc) if I apply a sealant like the Ductmate ProSeal to the seams on the inside of that box?
Thanks in advance.
 
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Old 10-20-22, 05:17 PM
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From Ductmate FAQ's..........

When using PROseal, does the joint need to be sealed from the inside or the outside?

The joint can be sealed from the inside or the outside of the duct. If the ductwork is exposed,
it may be more aesthetically pleasing to seal from the inside.


It will take several days to completely dry so that no fumes remain.
 
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Old 10-20-22, 06:55 PM
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Thank you Pjmax, this is helpful.
 
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Old 11-13-22, 01:07 PM
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I completed my project. The caulk is very thin. The good news was it didn't run on the surface, even on vertical seams. I have a no-drip caulk gun and I pulled the plunger back every time I paused. But this thing kept oozing out and dropped all over the place. I must have lost 15-20% material due to this oozing out. Is this the expected consistency or did I just get a bad cartridge?
 
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Old 11-13-22, 05:18 PM
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I usually use the "paint on" sealant that comes in a gallon can.
Out of the can it's like thick paint.
 
 

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