I have two vents below a large picture window on my late 1950's single-story ranch with a basement (full-ceiling height) and cinderblock foundation: enter image description here

The holes do not go anywhere and I am having trouble coming up with a reason why I shouldn't either repurpose them as part of a new Energy Recovery Ventilator install or otherwise insulate and seal them off.

The vents have been here since before I moved in and for whatever reason, I never gave them much thought beyond adding screening to them to keep out pests when I realized they were completely open on the bottom and had no idea about a lot of the inner-workings of home systems at the time. Recently, I've been thinking about adding an Energy Recovery Ventilator to get more fresh air in my home and thought these two vents on the front of my house might be from some variety of old leftover venting system that I could repurpose. As it turns out, the holes just lead to the empty wall cavities beneath my picture window and are completely surrounded on all sides by framing members (additional pictures below).

Does anyone have any idea what these holes might have been (or still be) for since there are no signs of any other tubing or cuts in framing to suggest there was ever any more tubing attached? As it is, I'm thinking about either repurposing the holes for my ERV (or minimally insulating and sealing them off). In case it helps, a large window or set of windows is original to the home's design (my house is a cookie cutter design and I have seen at least one home with the original windows), but I believe it may have been widened when a newer window was installed. That said, these vents sit pretty squarely beneath the window where I would bet they would have been beneath the original window's span as well.

View looking straight-on directly into the hole: enter image description here

View looking directly right with inspection camera from hole entrance: enter image description here

View looking directly right with inspection camera from hole entrance: enter image description here

I didn't take a picture of the left or down because there are obvious framing members at both points from outside the hole.

  • 1
    What's in the basement? Was there a laundry room beneath the room with the window? Oct 10, 2021 at 17:49
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    @JeffWheeler Laundry room has always been on the opposite side of the house with the furnace and water heater -- even had the old gas dryer hookup removed several years ago myself. It's just empty space in the area below these vents and there are no bored holes in framing members or joists to indicate anything ever ran to these vents. Oct 10, 2021 at 17:52
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    Theory: Two-pipe portable A/C. Does the interior wall beneath the window look renovated or patched, so maybe those holes once went through the wall? Is there central A/C that was added recently, possibly replacing portable and window A/Cs?
    – jay613
    Oct 10, 2021 at 17:58
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    A) Very well asked & documented question! B) You state it's a cookie-cutter house in a neighborhood filled with 'em. Have you asked any of your neighbors about their houses? If they've still got the original windows/layout, then you might be able to stick your endoscope in their vents to see what others look like. There may have been more work done to yours than you know.
    – FreeMan
    Oct 11, 2021 at 18:09
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    @FreeMan Funny you should mention that, it’s on my to-do list to check out a few other houses in the neighborhood as the last step before smashing the accept button on jay’s answer. Oct 11, 2021 at 22:37

1 Answer 1


Maybe there was a dryer in the basement once, later removed, and at some point the window was enlarged and the framing around it renewed so there is no more hole to the basement. But that doesn't explain two vents. If there was a bathroom in the basement, it would probably still be there and you certainly would have told us about it. I can't think of any reason there would be two vents like this serving the basement in a way that left no trace for you to discover.

The only explanation I can think of for two vents is: at some point there was a two-hose portable A/C in that location, with vents installed nicely in the wall so they would not interfere with the window. Later, central air was added, and the interior wall beneath the window completely renovated as part of enlarging the window. But there was no motivation to remove the outside vents and repair the brick, perhaps because the window installers would have had to sub out the brick work but were able to do everything else themselves.

enter image description here

I don't think you'll get a history of these holes than can be proven or disproven but I think it is perfectly safe to repurpose them and in fact if your entire exterior is brick it is the correct approach, rather than sawing new holes in the brick elsewhere.

  • After confirming by looking at a few other cookie cutter homes in the neighborhood, the vents are definitely not an original feature and this seems like the most likely answer. Oct 19, 2021 at 23:07

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