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I am trying to understand what is the proper way to ventilate a basement. I have a finished basement which if not ventilated starts to smell ..like a basement :-) and I don't like it.

If I run the AC fan continuously the problem diminishes but I get a slight smell upstairs (a raised bungallow, above the grade windows for basement)

What are the recommendations for properly ventilating the basement? The basement has an apartment with a kitchen and a bathroom that have their own ventilators. On top of that I have the chimney for the old furnace. I am thinking about using any of these to evacuate the smelly air and I hope that better air will be sucked from upstairs .... will this work?

Edit: I already bought a DeHumidifier. Last year I had some problems, acute problems I would say, strong smell. This year is much better. In winter the furnace did most of the job and the smell almost disappeared. The hygrometer measured around 35-40% RH at 21C. Now since the AC does not start I am at 19-20C downstairs and 23C upstairs with 45-47 humidity downstairs and 41 upstairs. If I run the DH constantly I can hardly squeeze any water from the air, looks like it is not very efficient. The DH has it own hygrometer, not really in sync with the other one that I have down there but they go up and down in sync. So the DH does not seem to solve the problem

  • If it's not humidity, then it's possible water ingress. Is it a poured concrete foundation, or cinder block? Is there a perimeter drain and sump pit? – Tester101 May 20 '16 at 14:46
  • it is cinder blocks, I have many posts around here about trying to guess what is the source of my problem. For now I just need to understand how to ventilate the basement properly. Dealing with the source of the smell will come later when I have the time to remove the drywall and the insulation and to see what a heck is going on behind it. I would like the focus of this to be the ventilation only – MiniMe May 20 '16 at 14:49
  • solving the root problem is the solution. – Tester101 May 20 '16 at 14:53
  • You have tried dehumidifying with little success. Perhaps it is just lack of ventilation. Why not jury-rig a small exhaust fan and see if that takes care of the problem. Also, do all the rooms in the basement have the same smell? – Yehuda_NYC May 20 '16 at 15:34
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    You should probably look into continuous mechanical ventilation, typically implemented with a Heat Recovery Ventilator. One link, there are more if you go looking for it; likely you can find a Canada specific version, this being a USA specific version: energytrust.org/library/forms/… – Ecnerwal May 20 '16 at 16:21
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Sounds like dehumidification might be the answer. The cause of the dank "basement" smell, is high humidity. Removing moisture from the air is a side effect of refrigeration, which is why the air conditioner helps. A dehumidifier is just like an air conditioner, except that the dehumidifier heats the air back up after cooling it and removing moisture.

You may be able to simply use a standalone dehumidifier, though then you'll have to dump the collection bucket. Another option, is to install a whole house (or whole apartment) dehumidifier. A whole house unit will be more expensive, but won't require dumping a bucket or water once a day.


If you have moisture problems in the basement, you'll want to sort those out. That should eliminate the cause of the foul air, and the need for removing it.

If you don't want to deal with the moisture problems, then you'll have to focus on removing the foul air and replacing it. This means drawing in outside air, conditioning it (heating, cooling, filter, humidify, dehumidify, etc.), and exhausting the foul air.

If you live in a mild climate where indoor and outdoor temperatures are similar, this shouldn't be that bad. However, if you live where indoor and outdoor temperatures are extremely different, you're going to be paying a lot to condition the air.

You'll want to look in to a heat recovery ventilation (HRV), and/or energy recovery ventilation system. As these systems will help reduce the amount of heating/cooling that will have to be added to the incoming air.

Drawing air from one dwelling unit into another, is not a proper solution. Air must be moved within a single dwelling unit, or between the inside and out.

  • This is correct. Here in Minnesota it's far more humid that outsiders would expect in summer, and dehumidifiers are almost a necessity. Set one up in your utility room where you have a floor drain (most models are convertible) at 50-55% RH and be happy. – isherwood May 20 '16 at 14:15
  • Please see my updated to the original post – MiniMe May 20 '16 at 14:28
  • I live in Ontario Canada – MiniMe May 20 '16 at 16:08

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