Sealing Basement Ceiling Vent Air Leaks

Last year, we wrote about an issue I was having with a particular vent in the drywall ceiling within one of the rooms in our home’s basement.

The issue I was having was that due to the poor installation of the vent by the prior owners (not that I am an experienced basement finishing expert myself … which I am not icon smile Sealing Basement Ceiling Vent Air Leaks ), I was having a hard time installing a vent cover or register. The opening was constructed such that I could not fit into it a standard vent register. As well, there was nothing for the screws of any vent register to use to hold the register up in the ceiling.

Two things which came out of that experience.

First, I was given a great idea on how to install the heating vent register by my local Home Hardware store based on the sales associate’s own experience.

Second, as Vasile, a long time visitor to, pointed out, I still had air leaks because I neglected to address the rough metal at the end of the vent duct.

Life has a way of interrupting the best laid plans.

It took me until a few weeks ago to attempt to address those air leaks.

To put the situation into context, below is a picture of the current situation.

basement ceiling vent register Sealing Basement Ceiling Vent Air Leaks

You can see that I used a vent cover typically used for a cold air return rather than a register used for a heating duct.

basement ceiling vent leak Sealing Basement Ceiling Vent Air Leaks

In the second picture, directly above, you can see the opening that I have to work with. Look how much space exists on the lower part of the picture between the rough edge of the vent boot and the vent frame built between the ceiling joints and the drywall. Wow.

vent opening in drywall ceiling Sealing Basement Ceiling Vent Air Leaks

And, in this third picture (above) is again the same opening but showing how much space is between again, the very rough end of the metal bent boot and the vent wooden vent frame.

Two things are working against me here, because it is a drywall ceiling. I loath drywall ceilings in basements. If you have a water leak of any type, to fix it you have to break the drywall in the ceiling and then spend lots of time as well as effort repairing the broken drywall. As well, you have to rely on whoever installed the drywall in the ceiling that they first sealed all of the ducts to prevent air leakage of hot air from the furnace (in the winter) and cooled air from the central air conditioner (in the summer) to not waste electricity, natural gas and / or home heating oil and cost you money through higher utility bills.

It you are concerned with energy savings on your heating and electrical utility bills at all, you will use a drop ceiling in your basement.

First, I am not about to break the drywall and repair the shoddy workmanship.

Second, because of this, I cannot get any leverage to fix the shoddy finishing of the vent boot edges.

I have to come up with another solution to stop the large air leaks costing me money.

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  1. Joan says:

    I got to your website as I researched sanidry systems. One basement company proposed that as a solution and another proposed the humidex system. Can you give me any comparisons or advantages of one over the other? ( I recommended your site to a few friends- it’s informative and fun to read!)

    • Dan says:


      I am sorry but I have no experience with a humidex system so I cannot compare it to the SaniDry dehumidifier we are using.


  2. Shaunna says:

    I just started painting our basement ceiling and was annoyed to find this exact problem. The ceiling vents do not even come close to the drywall opening. I would love to know how you might seal up the gap?

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