I am replacing my dryer exhaust vent. Here is a picture of the old one after I removed the cap.

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I did my best to clean up the old caulking before adding the new tube and vent, which looks like this:

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As you can see, it's not sealed very well against the brick. I'm not really sure how to go about that. I can't really just splork a bunch of caulking in there because the gaps are too big, especially in the grout lines.

The other side of the vent where the dryer hooks up is fairly well sealed, so I'm not too worried about that.

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But for the outside, do I even need to worry about the sealing plastic cover against the brick? Or should I focus on sealing the metal tube, maybe with caulk or spray foam? The gaps around the tube are definitely caulkable, assuming I can take the plastic cover off the tube to get access.

Thoughts on approaches here?

FYI, I'm in Austin, TX and the dryer is located in the garage.

  • I was walking my dog through my neighborhood one day, along a row of townhouses and heard a (relatively) strange scratching, tapping, scraping noise. I looked at the houses and finally saw it. A bird was flying up to a dryer vent cover that looks just like yours, and while continuing to furiously flap, was pecking and clawing at the louvers. After about 4 or 5 attempts, one of the slats came up just enough for the bird to be able to grab the one below with its claws, and pry the louver up enough to climb through.... a few minutes later, it came back out and then later rinse, lather, repeat.
    – CGCampbell
    Jul 1, 2020 at 22:51

4 Answers 4


In the end I used a sealant putty called Mortite to fill in the space between the tube and the brick. I tried low expansion foam but as it expanded and dried, it squeezed the tube out of shape so that I couldn't fit the cap back on. There was really no way to caulk that area because once the cap is on, you can no longer access it.

So basically, I put the vent into the hole with the cap on, secured it to the wall on the other side to it wouldn't move, and took the cap off. Then I smooshed the putty into the cracks and placed the cap back on. Had to get some help to make it work but it wasn't too bad overall.

I also went ahead and used the putty to seal the metal collar to the wall on the other side where the dryer hose connects.

Also I used Loctite to glue a piece of broken stone back onto the wall on the right of the hole.

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  • You found a good solution. "There was really no way to caulk that area because once the cap is on, you can no longer access it." ?? In my answer i assumed you would know that you must caulk the pipe in the wall before you put the new cap on. You definitely need to replace that flimsy, dangerous plastic dryer vent tube with a metal one.
    – Alaska Man
    Jul 3, 2020 at 19:11
  • Thanks for coming back and outlining your solution! However, I think you need to replace that non-metallic exhaust hose with a metal one (code in my area requires metallic dryer vent hose)
    – Matthew
    Jul 3, 2020 at 22:43
  • Yeah I'll replace the hose with a metal one
    – d512
    Jul 5, 2020 at 17:58

You probably don't need to worry too much for sealing against the air coming out, since it is practically outside.

The sealing outside is important for a different reason: to prevent animals coming in.

You may want to look into how to do that instead of thinking about airflow. Nothing messes with your vent like a family of birds living in it, or other less desirable animals. For this you'll be looking at more durable meshes instead of air-tight sealant.


The Only thing you need to worry about is water entering the wall between the brick and the duct.

Before you put your new cap on run good thick bead of caulk around the outside of your duct, make sure you get it in so it seals the space between the duct and masonry. This will be much easier than trying to caulk the cap in place with all the contours of the brick and mortar.

Any water that get behind the cap (the plastic housing for the louvers) will not penetrate the wall, it will just flow out the bottom of the cap.

  • With the new duct tube in place, I think the gaps are a bit too wide for normal caulk. How about a low expansion foam like Great Stuff ® or Loctite™?
    – d512
    Jun 30, 2020 at 21:38
  • You can apply caulk in multiple layers. Apply the amount that still holds, let it dry, and then apply another layer on top. It's not optimal but sometimes it might be easier to deal with than another material, since expanding foam and other fillers of that width are not necessarily sealants against water; just literally space fillers.
    – Nelson
    Jul 2, 2020 at 1:58
  • Yeah I tried the expanding foam and it was a mess. I had to take the cap off to do it and as the foam expanded and dried, it squeezed the duct into a different shape so I couldn't fit the cap on anymore. I had to destroy the duct just to get it out. Lame.
    – d512
    Jul 2, 2020 at 15:06

As others have said I would not worry buch if the pipe connected to the vent, if the vent is just a cover you don’t want lint hanging out of all the mortar gaps. I draw a line with soap stone at the edge of the cover and remove it now fill the voids 1/2” from the line and re install the cover this will direct the lint out the front. I don’t use a pencil in this case because the black graphite is always obvious For years soap stone is white and washes off with normal weather.

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