Quote:
Originally Posted by javadog
Moisture can condense on anything cold and concrete, if it is exposed to the exterior, certainly qualifies. It’s not hard to get condensation inside wall structures. Vapor barriers are funny things, they need to be in different places in the wall, depending on where the higher humidity is and what side of the wall has a lower temperature.
One test we would always do on a concrete slab to check for moisture ingress was to tape a piece of clear plastic down onto the floor and see if moisture accumulated inside it over a period of a few days. Easy to do, you should try that in a couple places. I would suggest one near the outside wall, or close to wherever the moisture sources might be.
When you mention the smell, you described it as moisture and not mildew. Wet concrete gives that odor.
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The crawl space smells like a … 3 year old parking garage. There’s concrete smell in the air after I climb in. It’s not moisture smell but like concrete that has eaten all the water and wants more, and it’s caustic to my sinuses. Concrete dust.
The room, when it’s left for a week without dehumidifier… smells wet. Not mold, no dank, just wet air, maybe a bit like wet latex paint. My wife and kids can’t smell it but my father and I can. After dehumidifier runs it smells like nice wood and cheap carpet, and a bit of oil paint on window trim still drying after 25 years.
Good idea about the plastic on concrete!
The rooms windowsills are on the top of the foundation wall, and at ground level. Inside they’re about 3ft above the subfloor. So foundation wall is 6’ of dirt against it. Weird topology outside the dirt slopes steeply down away from the windows, maybe that’s why there isn’t high water pressure forcing water inside. But I’ll do the plastic test and see. It all looks crazy dry. Like I said above the crawl space looks and smells new after 55 years.
I went back down and I’m pretty sure the crawl space is drier than the room above. It’s like being in desiccant. Like cement dust is still active.
I’m going to keep the guest rooms door closed a few days with dehumidifier off and see if it stays dry. Normally it’s always open and folks often leave garage door open.