I have a very damp cellar, about 80 square metres. The reason for the damp is the outer membrane and the drains that run at the bottom of the cellar walls (outside) has broken down. The long term solution is to dig out all around the outside and replace the membrane and drains, but finances don't permit that this year.
But in the shorter term I want to try and reduce the moisture level in the cellar. So is it better to ventilate the cellar, or keep it unventilated. I was thinking that if I bring in fresh air, due to the temp down there, about 8 deg, the moisture from the outside air will simply condense out in the cellar, thereby making it no better, or worse.
I've tried running a reasonable size dehumidifier, but it just runs flat out and barely makes a difference. I guess the damp is coming through quicker than it can remove it.
So what's the best solution, if there is one, to reduce the humidity levels (currently around 75%rhd)?
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Outside air is much drier than inside air. Therefore introducing ventilation is a good idea. There are two ways of doing it.
Insert airbricks; or
install a constantly running fan to extract air to outside.
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Make sure you draw outside air in, not house air, which can be laden with moisture.
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I'd go for a good forced-air ventilation system, home made with a fan, possibly.
It's a big cellar. Is it a new one, or old? In the absence of actual running water, tanking is an obvious approach.
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Im my cellar there is a large tube on the inside wall & on the outside wall is the air brick, so good flow comes through this into the cellar to keep dry but i use the tube also for the tumble dryer vent, if i leave the pipe in the the tube like i forget to take it out you can smell damp after a few days.
So much better to have a flow of air & i also have the central heating boiler down there so the heat from this helps too.
More vent and unblock your air brick is the key.
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The cellar in our previous house had airbricks.... you could see through them so air flow was okay. Walls still damp mind but it was a cellar. The new house will need checking when we get the keys.
I would have thought you need more than air flow into a cellar to keep it dry though. The moisture has to go somewhere.
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Well I've put in a vent axia type fan in one of the windows, and opened all the others a little as well. Also opened the boiler doors so there should be a healthy updraft through the chimney. Trouble is, it's about 80%rhd outside just now, so have to wait for the thundery weather to subside a little. Only about 2/3rds of the cellar is actually underground, so there are short windows around the outside.
I also have an 'earth cellar' in the garden, that's a hole in the ground with walls of solid stone, and earth heaped on top. They were used to store potatoes many years ago. It has a chimny typre vent, and last year I cocked the door open a little to let air through. But the outside air seemed to bring in so much moisture that the walls and floors were dripping wet. In the winter it stays dry.
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Having fans blowing onto the walls will help the transfer of the moisture from the walls to the dehumidifier.
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Ventilating cellar - Netsur
