Home & Garden

Pest screens over external fan vents?

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  • Jun 6th, 2021 11:14 pm
[OP]
Jr. Member
Nov 1, 2015
100 posts
158 upvotes
London, ON

Pest screens over external fan vents?

Usual disclaimers from me: I'm not handy and just doing my best to learn about maintaining my home.

What screens do you get to go over the outside of builder-standard vent flaps, to prevent intrusion by mice and birds? Referring to bathroom fan vents. Not the fine screens for insets, just trying to prevent nesting.

How do they attach to a brick facade? I am very intimidated by the idea of drilling into the side of my house, especially while up on a ladder.
12 replies
Deal Addict
May 10, 2011
1469 posts
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Ottawa
Most animal control companies use wire mesh that you can find in any home improvement stores. Cut a piece that is roughly 4" bigger in both width and height than your vent opening, then bend it into a "square dome" shape, leaving an inch of overhang on each side.

And to attach to the facade, you need to drill hole into the brick with a hammer drill and masonry bit, then just attach the mesh with masonry screws and washers. You can get a kit with the correct size bit and screws in the hardware section. Just get some washers to go with them.

Drilling hole into the brick is actually no biggie. If you make a mistake at least it is very easy to patch the hole.
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Feb 11, 2007
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Oakville
Curiousah wrote: Usual disclaimers from me: I'm not handy and just doing my best to learn about maintaining my home.

What screens do you get to go over the outside of builder-standard vent flaps, to prevent intrusion by mice and birds? Referring to bathroom fan vents. Not the fine screens for insets, just trying to prevent nesting.

How do they attach to a brick facade? I am very intimidated by the idea of drilling into the side of my house, especially while up on a ladder.
You can replace those vents with ones that have mesh built in. You can also just add a piece of window/door screen behind the vent (not dryer vents).
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Dec 19, 2009
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Curiousah wrote: What screens do you get to go over the outside of builder-standard vent flaps, to prevent intrusion by mice and birds? Referring to bathroom fan vents. Not the fine screens for insets, just trying to prevent nesting.
Exhaust vents like bathroom fans and dryer vents don't normally need screens as they have dampers on the vent termination that closes when the exhaust air stops keeping insects, the cold, etc from coming back in.
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Jun 12, 2007
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pootza wrote: Exhaust vents like bathroom fans and dryer vents don't normally need screens as they have dampers on the vent termination that closes when the exhaust air stops keeping insects, the cold, etc from coming back in.
I think he's worried about birds - starlings

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Oct 13, 2008
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I took out the flaps.

Then used small metal wired mesh and gorilla glued it to the plastic frame.

Then slightly sanded down the ends of the flaps.

Then put the flaps back in.

Done
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Feb 25, 2004
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pootza wrote: Exhaust vents like bathroom fans and dryer vents don't normally need screens as they have dampers on the vent termination that closes when the exhaust air stops keeping insects, the cold, etc from coming back in.
They can lift the damper and enter. It happened with my dryer exhaust and my kitchen hood.

I installed metal wire mesh that I screwed into the metallic "box" of the exhausts.
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[OP]
Jr. Member
Nov 1, 2015
100 posts
158 upvotes
London, ON
l69norm wrote: I think he's worried about birds - starlings

Yes, this is why. Thanks to everyone for letting me know what you've done. I'm going to try to add galvanized pest screening behind the louvres. Only bathroom fans, not the dryer vent.
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Mar 21, 2002
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That's right, you can't put anything on the dryer vent because it would get clogged with lint and create a fire hazard.
Jr. Member
Aug 20, 2007
109 posts
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Thornhill, ON
I'm in the same boat as op, I've got a family of birds in the bathroom vent pipes.

Please tell me if this makes sense:
1. Once the baby birds leave (should be in a few weeks I've been told), I will clean out the pipes of their mess (nest, worms, dirt, etc.). Maybe spray a disinfectant (?)
2. I will remove the flaps from the cover (I don't want to remove the whole thing because it was professionally caulked in) and install a wire mesh, so when the birds lift the flaps, they wont be able to get in
3. hope that I did a good job

please let me know if there's any steps I'm missing
and
1. Should/Could I spray a disinfectant? And if so, what do you recomend?
2. Is this a good product: -it seems easy and inexpensive enough

https://www.amazon.ca/dp/B08NPP7GH9/ref ... HJ1ZQ&th=1

Thanks :)
Deal Addict
May 23, 2006
1084 posts
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Vancouver
The vents should be quite tight if the builder do the job properly. However, if rodents can easily get on your roof, they will chew around and eventually make a hole; that's when the mesh screen is helpful. It's an extra safety.
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Mar 21, 2002
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quisibo wrote: 1. Should/Could I spray a disinfectant? And if so, what do you recommend?
I don't see any need for a disinfectant since air in the vent is blowing out of the house. It wouldn't hurt though - just use a standard household spray like Lysol.

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