crawl space dehumification

Matt_21

under a condo. concrete poured floor, insulated walls. owner wants dehumidifcation unit to avoid mold and musty smell in the summer. the a/c unit and ductwork runs in the crawl space. would some supply and return from the a/c unit suffice or is there a small dehumid. unit i could install?

jerry scharf_2

sounds like more is going on

Matt,

Mold smells can be serious stuff. There has to be a reason for there to be more mold in the crawl space than the outside air.

There are a bunch of things that can be done, but first you need to understand why it smells that way in the first place. It it groundwater or some other water that is feeding the mold? Does it only smell in certain seasons. The idea popped into my head to see where the A/C condensate is going. there is no reason for there to be any more mold in the crawl space than the outside air.

After you figure out what's going on, the next thing is to figure out how far the problem has spread. Just because the report is from the crawl space doesn't mean that's the extent of the problem (or even the source.)

ME says water is lazy. When you're chasing after these things, it can seem pretty industrious and downright sneaky where it can get to.

jerry

Matt_21

there is no

mold in the space now. i'm working with a new plumber and he mentioned he wanted dehumification in the crawl space. we primarily do commercial work so i'm more familiar with large pool dehumidifiers. i didn't know if there was a small residential unit that someone made to stick in the space or if i should stick a small unit like you would throw in your basement? i forgot to mention there is no ventilation in the crawl space. the plumber is installing the radiant mains and manifolds in the crawl space so during the winter months, the space will be conditioned.

Constantin

I would...

... try to figure out why the space is humid in the first place. For starters, I would cover the slab with a 6 mil layer of PE to ensure that the moisture is not coming from the ground up. Seal the PE around the edges.

Then I would go around that crawlspace with industrial-sized cans of "Good Stuff" or whatever to stop air infiltration into and from the home. The edges of the perimeter, as well as all penetrations into the home should be sealed.

I would install a dehumidifier only as a last resort. While they don't consume gobs of energy, there are usually more efficient ways to keep the water out.

Fred Harwood

Crawl space

In addition to ground water in crawl spaces, consider that relatively warm air is also humid, and will condense on concrete cooled by ground contact. Indeed, air can supply most of the water in such situations. If so, the answer is to stop the air entering the crawl space, or heat the space.

Dale

Crawl space

Most recent research shows that the crawl space should be part of the conditioned space as much as possible. So, as the other posts suggested put down a vapor barrier to keep the ground moisture out, if you insulate under the vapor barrier with blue board the area will be closer to room temp. Put a blower door on the space and find out if there's leaks from the outside. Seal all of those. Tape or mastic seal the duct work.

Uni R

Vents

I would seal it up from outside moisture and then the first thing I would try and do is just see what can be done to add non-mechanical ventilation to the crawlspace.