Insulation, Radiant and Vapor Barriers - humidity in cold cellar

Hi,

I am having a humidity problem in my cold room in the cellar. It is beneath my front porch of the house and is constructed of poured concrete. There doesn't appear to be any visible leaks, the ceiling is "insulated" with rigid foam insulation boards. The outside walls are below grade and are not insulated. The wall between the cold cellar and the rest of the basement is insulated from the inside of the house, not in the cold cellar itself.

The humidity is around 100%, and has a musty smell.

I'm interested in getting rid of the musty smell, and I'm guessing the best way is to get rid of the humidity.

Besides installing a dehumidifier are there any recommendations to achieving this? Seal or paint the walls? Install insulation on the walls facing the grade (outside)?

Thanks,
Jason

The dehumidifier is the place to start. Make sure you get a dehumidifier that will work in the temp range you are experiencing. While that is lowering the relative humidity (RH) you will need to determine where the moisture is coming from, through the walls, or from moist air circulating into this area. You did not mention a door. If it is just moisture difussing through the concrete walls, the dehumidifier will handle it easily. If it is outside air being vented in, then there is a constant supply of new moisture. Warm outside air with normal humidity will become high humidity (RH) when it cools to the temp of the cold room.

So, run a dehumidifier and see if it can keep up with the moisture.

Bud

I agree! Don't know where you are located but if you are in a green grass state a dehumidifier will be needed in the basement for good IAQ.

thanks....

I'm in southern Ontario...you know, where polar bears live.:)

The door...glad you asked....the door to the cold room is just a plain old interior door. Probably an insulated (or steel) door would be in order.

If I do keep the door open in the summer the humidity seems to go right down to about 50%...unfortunately the musty odor infiltrates the rest of the basement, then ultimately the house.

I really don't care to have a cold cellar, I'd prefer to use it as a storage area. (it's about 40ft by 5ft)...but I need to keep the humidity down and get rid of the musty smell....if I want to store anything of value in there.

Thanks for the suggestion...perhaps I'll "borrow" my dads dehumidifier just to see how that goes. I'll also consider painting to keep the cement dust to a minimum.

When you write about humidity it helps if you provide the temperature at the time as humidity is always relative to temperature.
For example at 86 degrees f the humidity of 100% = 30 grams of water per cubic metre.
At 40 degrees f, 100% humidity only = 5 grams of water per cubic metre.
At 86 it feels hot and wet, at 40 it merely feels cool. Yet both are 100% humidity.
The thing to do is buy two remote wireless humidistats and hang one in the cellar and place another outside.
This will tell you if the water vapour in the cellar is coming in as an air change, probably caused by holes in the floor, with the home above, sucking the air from the cellar as the warm air in the home rises and goes out through holes in the ceilings and walls.
Or if the water vapour is rising from the ground or walls (unlikely as they will be cold compared to the air temperature.)