Crawl space fixing

[RalphVa]

We ended up with a odor from our crawl space this year. Been doing fine with an AC discharge into it and 3 fans going. Had tried a dehumidifier in the past, but was just overloaded and heated space too much. Bothering the wife. I absolutely cannot smell it at all.

Have removed insulation in ceiling of crawl space. Don't need it now that it is encapsulated and vents sealed off (did this in 2011). Found a tiny bit of mold on some of the insulation.

Had a duct cleaning outfit in. They cleaned the ducts and replaced the plastic ones.

Wife wiped down all surfaces in crawl space and in adjacent utility room with bleach solution.

Had an air quality guy in yesterday. He says it's from bacteria underneath the encapsulation. Says to seal up the AC exhausts into the family room above it where wife spends the day; none of them are sealed well and are entraining air from the crawl space into the family room from the leaks. Seal leaks with duct tape. He recommends a commercial grade dehumdifier for the crawl space, Santa Fe or Aprilaire. Says to shut off the AC exhaust into the crawl space.

What's your experiences with crawl spaces?

Ralph

 

[mrmikey]

Says to shut off the AC exhaust into the crawl space.

So the exhaust going into the crawl space is moisture laden air? That's a recipe for disaster

Don't need it now that it is encapsulated and vents sealed off (did this in 2011)

So there's no air circulation at all?

Sounds to me like a dead air issue. When I bought the place I'm in now the previous owner had sealed up the 4' crawl space solid, no air circulation whatsoever, he was even going to vent the dryer into the space, luckily he sold it before that. It smelled terrible, musty, dead, damp etc.
I opened up two small openings 'bout 12" square at one end and a 2' x 2' at the other and mounted a remote controlled fan in the big opening. Even without the fan going the difference was immediate, with the fan going in the summer the place has no odour at all and even feels dry. Even in the winter with the large opening blocked off and just the two smaller ones open the difference is noticeable..........Mike

 

[oldballs]

I hand dug/bucket out the dirt crawl space down about 8 inches (about 20 x 15) below the footings....forty five yeas ago. Then replaced that with equal amount of gravel. There is one foundation vent...and the area is not totally sealed off from the rest of the basement. The far outside corner was walled off and a raised wooden floor allowed for storage of potatoes thru the winter...

The whole area is now a great place to store all kinds of stuff without mildew or mold. I'm only 5'3"(and shrinking), but have to bend to get around under there.

Cheers,
Mike

 

[RalphVa]

Exhaust I mentioned is return air from our HVAC system. It's conditioned, dehumidified air.

The international regs for crawl spaces is to vent them if dirt and to stop them up if encapsulated.

Just wondering about experience with these industrial grade dehumidifiers.

Ralph

 

[Oldstuff]

I have been through what you are dealing with except I did not have any odor. Built a new lakehouse in srping/summer of 2018, this is in northeast Missouri- Missouri has bigtime humidity in the summer months. Concrete crawl space (4-feet tall) and have plastic on the floor with 1/2 inch clean gravel on top of that. I also glued 2 inch thich pink foam board on the walls all the way around for winter freezing protection. Everything went fine through the summer except when down there i could feel the humidity but never did actually check to see how much. It is 28 by 44 feet with 2- 8 by 16 inch vents on each end that can be opened or closed. As winter approcahed and got cold the foam on the foundation walls started sweating and the insulation was getting heavy with the added moisture, the paper of the insulation was soft and loaded with humidity.

I did a ton of searching on the web and learned of total encapsulaing but felt I could and did solve the problem with out that much expense. One thing I learned is that the cool/cold air will NOT hold as much humidity as warm air in the summer that is why it formed on the walls. Another is mold starts growing at about 70% humidity and around 65 degrees. My temperature down there in the winter is usually 58-60 degrees. So I did the following- I leave the vents closed year around, I added another layer of poly on the floor and where it meets the edge of the basement I laid treated 2X4's on top of the plastic on top of the footing. Sort of encapsuating but nut not sealed 100%. I added a dehumidifier and ran the discharge to the sump pump and set it at 55% and it now cycles on and off and my humidty is stable at 55%. The insulation dried out in a couple of days and the paper on the insulation is now crisp like paper should be. I feel the added plastic and the dehumidifier is what solved the problem.