The mesh grate on the vent hood at my local big box store is only useful for keeping out birds and the like. I'm tempted to wrap the whole thing in window screen but that would likely reduce air flow significantly. What is the best way to install an air inlet without it becoming a highway for insects and spiders to enter my home?

  • Do you have pictures?
    – Huesmann
    Commented Jan 7, 2023 at 13:56

1 Answer 1


If you think the screen will reduce airflow by 50%, then double the area of the inlet.

If you've got a 2" diameter pipe, get a 2" to 4" reducer/expander, attach the 2" end to your existing pipe and put the mesh over the 4" end.

Going from a 2" to 4" diameter is significantly more than double the square inches, so you should be fine.

If you think the mesh will reduce air flow by more than 50%, enlarge to the size you feel is necessary.

  • Would window screen reduce airflow? The holes are tiny, but so is the material.
    – crip659
    Commented Jan 6, 2023 at 0:49
  • 1
    I wouldn't think it would have a significant impact on airflow, @crip659, however the OP thinks so. I believe there's a non-zero chance that the whole question is based on an incorrect presumption, but, assuming he is correct, this would be a reasonable answer.
    – FreeMan
    Commented Jan 6, 2023 at 1:13
  • 2
    Remember that you'll have to clean it more often. Fly screens collect tons of dust, lint and other matter that will eventually reduce your air intake dramatically.
    – throx
    Commented Jan 6, 2023 at 2:48
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    Make sure you seal around the outside of the hole you cut, too, @Tag. Also, what kind of system is this feeding into? I've got an exhaust vent for my furnace that doesn't have any sort of screen over it (I think, recently installed and I haven't taken the time to look). But, if bugs crawl into it, they're only going to get as far as the combustion chamber of the furnace before life gets too hot for them...
    – FreeMan
    Commented Jan 6, 2023 at 12:46
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    @tag Instead of window screen, you can buy a jumbo sized strainer (like a tea strainer but bigger), then cut and flatten the stainless steel mesh. It's much more durable than window screen, so easier to keep clear of dust using a bristle brush.
    – MTA
    Commented Jan 6, 2023 at 14:19

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