basement humidity

gene_2007September 1, 2007

The quick question - Should I / Can I add a return duct to the basement in order to reduce humidity in the basement?

The details -

I have a "finished" basement. It doesn't feel like one since it was done in the early '60s with panelling and other out dated materials. Some areas of the basement are not finished (eg. exposed foundation), like the laundry room and a closet.

The basement is very humid - at least it is now in the summer. I haven't checked it in the winter. My dehumidifier is filling to capacity and shutting off at least once a day. I empty it before work and when I get home, it is full. When the dehumidifier was not running for a few days, the humidity was 80%. When it is running, the lowest I can get it is about 65%.

One thing I'm surprised about is that I can't find any condensation anywhere. I checked the concrete walls, panelling and the cold water pipes. Nothing.

I am about to remodel my basement and am afraid that excessive humidity will ruin it, although I don't seem to have any problems now (other than the humidity itself). There is no mold or odors.

The basement living area has the laundry room adjoining. The laundry room also contains the furnace and gas hot water heater. The door to this room is always open, so perhaps this is where much of the humidy is coming from? There are two washers and two dryers. Yes, the dryers exhaust to the outside. When I remodel, I plan on putting in a door and keeping it shut.

There is no A/C in the basement - don't need it. There is heat, but not from the furnace. It is actually connected to a heating system from another part of the house. The basement has hot water baseboard.

My furnace has a return run that runs across the basement and through the foundation to the outside. Some people told me this is good because it provides fresh air to the house; others say this is bad because the furnace has to heat freezing air.

Finally, my questions -

1) Keep the return duct to the outside or close it off?

2) Add a return to the basement living area?

3) Why is the humidy so high in my basement?

4) Will adding a return in the basement help with the humidy?

5) Will painting Drylock on the walls help with the humidy?

6) Are there other alternatives to help with the humidy? Should I get another dehumidifier?

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I'm not a pro, but can offer a little advise. You may or may not have already tried this ... Definately keep the dehumidifier running all the time with a drain hose connected to the laundry sink drain or some other means to get the condensation out of the basement. I did that this summer and it's been working great as far as humidity levels staying constant and not having the pain of emptying the buckets twcie a day.

I think the humdity is from air leaks in your walls. Maybe sealing/caulking everywhere will help matters.

Always keep in mind that you need air for your drier to work properly. If you'close the door' to the room, just make sure there is enough air for it. The same goes for anyfurnace or hot water heaters and stuff like that. This also ties into having returns in the basement with no supply vents. You need a 'balance' of return and supply air for any location really.

Just fyi... I purchased a separate small pump designed for dehumidifiers and such to pump out the water as it fills up from the unit. Works great if you don't have a drain handy. Good luck

    Bookmark   September 1, 2007 at 6:43PM
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Thanks, cissado. Your response was very helpful.

    Bookmark   September 1, 2007 at 8:10PM
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If it is easy to get a suppy and return into the basement it will only help its air quality. Make sure th supply is much large (3-4x's) to in sure positive pressure environment. You don't want to draw flue gases into your
a/c system. Always have a co alarm on each floor.

    Bookmark   September 1, 2007 at 8:23PM
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