Will dry air on a main level help with a humid second level?
1869farmhouse
| Posted in General Questions on
I’m working on a 20’s Bungalow and that has 90% of the living space on the main level, with a little office type area on the second level that is primarily used for storage – the second level is not conditioned.
We found some mold on the second level and the humidity was reading very high – 73% on my unsophisticated tools at 83 F. We’re going to be replacing the massively oversized AC unit with a 2 ton Bosch, which I’m certain will ensure the lower level has acceptable humidity levels. But will that help with the upper level? Or will the humidity remain trapped up there?
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Replies
Humid air does tend to rise, but unless you have a that second level completely closed off from the first, the humidity levels will tend to be fairly consistent within the home. I wouldn't be surprised to see a *little* higher humidity on the upper level, but if the lower level is conditioned and dry, the upper level shouldn't be very different from the first in terms of overall humidity levels.
If you do see significant variation between the levels, all you'd need to do is provide some air circulation with a fan to even things out.
Bill
Good to hear. I know temperature is basically impossible to balance with fans and airflow - god knows I’ve tried. I guess it’s the delta of the temperatures or something like that.
A RH of 73% at 83F is a dew point of 74F, that's crazy high. I would suspect there is a moisture source on the second floor. Something is leaking.
Normally, within a house the dew point is relatively constant, the temperature can vary quite a bit and the RH will vary with the temperature. If the whole house were at a dew point of 74F it would be raining on the first floor and in the basement.
I suspect the culprit is my cheapy meter, but I will absolutely do some digging. The ceilings are vaulted, so not much is hidden.
Before we make the leap to the problem is excess humidity lets consider the humidity could be another symptom. Are we 100% sure no liquid water is getting into the building? Roof leaks, window flashing, shower drain pan, cracked pipes and a hundred other water sources.
Walta
I know for sure there are no water pipes up there, but I’m going to probe around a bit more to be safe. The mold we found was primarily spattered around on boxes and books that were being stored. Very little was found on the structure itself.