My house has an unused cistern that abuts the foundation. I've cut a doorway into it from my basement and would like to use it as living space. I would like to install a door to obscure and soundproof the room, but that would cut off the only source of air to this air-tight space.

I can install a vent by drilling through the basement wall at another location, but I am wondering how can I safely ventilate the 600 ft³ room so that several people can sit in it for hours at a time.

I would prefer a smaller hole, which will I imagine will require an fan as opposed to just a hole. Does this mean I would also need a second hole to return air, or could enough air escape around the door?


A 4 inch diameter hole with a good fan might be sufficient to move air from the basement into this room under the use you describe. The space under the door might be sufficient to allow the air back into the basement.

Is the roof of this cistern room exposed on the surface, and, if so, is it shaded from the sun?

  • Apologies, my units was wrong: its 600 cubic feet, not square feet. And yes, air from inside to preserve heat. Aug 28 '18 at 16:08
  • 2
    If needed you can put a vent into the door itself to facilitate air movement. Aug 28 '18 at 16:32

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