Crawlspace Encapsulation and Dehumidification

[69porsche]

All,
I live in the South and have been thinking of getting my crawlspace Encapsulation and Dehumidification with appropriate materials. I would seek the professionals that do this as a living-We have plenty of humidity and moisture during the years. I know by wicking the moisture out of the air, it will keep the wood beams (stucco house) and sub floor free from anything more that XYZ of moisture content and keep mildew at bay as well as keep the crawlspace dry and clean.

Any one who has done it and if so, can you please share your experiences with it. Thanks

Gordon,

I used to own a company that did crawlspace encapsulation as one product offering. It's the real deal--we started by laying down drainage mat, then covered it with 20-mil fiberglass reinforced plastic sheeting glued together. 10-mil plastic went up the sides, glued and pinned to the concrete walls just below the floor joists. We'd then hang a permanent set-and-forget dehumidifier from the joists, set at 50% RH, with an outside drain. For chronically wet spaces, we'd also install a sump system, or integrate an existing sump into the system. We guaranteed the work against water intrusion for 25 years.

Besides reducing indoor air pollution (50% of the air you breathe is from the crawl, including vapors from whatever is living down there, peeing and pooping down there, and dying down there), it also controls interior RH. In houses with moisture problems that cause the wood flooring to get wavy, the system can reduce RH to the point where the flooring sits flat again. And indoor mold growth can also be better controlled (mold does not grow at less than 60% RH).

I arranged to have all the local west coast installers become certified by installing the system at my house. It changed a dark, dank crawl into 1000 sq ft of usable space. The plastic is white, so it looks like an operating room down there. Really a nice upgrade.

The process is called AdvantaSeal, and the company is AdvantaClean. In Charleston, the local AdvantaClean is run by a friend of mine, Mario Colangelo. I know that he does a lot of these.
https://www.advantaclean.com/charleston-sc/ He's a great guy, and can give you all the details.

[VincentVega]

I did the encapsulation part myself. Not the most fun job but after seeing a quote I did in a saturday. I added a few foundation vents and might add a fan to one. Surely not as robust as the dehumidifier but the moisture I saw before is gone. Worthwhile project, DIY or not.

[CurtEgerer]

Even homes with so-called 'dry' crawl spaces should have this done (and make sure to permanently seal off all the foundation vents). I used to investigate a lot of structural damage from crawl space moisture - the largest moisture source in nearly every building. Many times, someone would point out that their crawl space has dry sand. OK, great. But sand is porous and if you dig down a foot or 2 you will eventually hit wet sand (unless you are in an area that has several feet of well-drained natural sand and no groundwater problems.) And that moisture vapor travels freely up thru the sand, and into the crawl space, living space, and attic.

[id10t]

Mom just dropped a ton of money getting hers done fixed.

Long time issue w/ humidity - not enough ventilation of the under space, bad drainage off roof used to flow under (now directed to pond via pipes), etc. Drainage issue fixed, mold killed/blasted out, encapsulation, etc. replace a few floor joists, etc. Big job, don't have full details or cost.

[kach22i]

In Michigan we have a section of the code dedicated for Radon, you might want to see if there are any addendums to 2015 IRC for your state though your building department.

https://up.codes/codes/south_carolina

ASIDE: My barber is convinced his wife got brain cancer because she worked out in the basement and the adjoining crawl space that tested 10X above acceptable limits was seeping Radon down into the basement that tested fine prior to an addition.

I usually draw well vented crawl spaces with access hatches in the closet floor or an exterior side panel, but several builders have opted for the sealed/heated crawls with access via an opening at the upper part of a basement wall.

Radon Map


https://www.radonaway.com/radon-contractors-usa.php


https://www.naturalhandyman.com/iip/infsisters/infradon/infusaradon.html

All homes should be tested regardless of geographic location.

[A930Rocket]

What part of Charleston are you in?

Being in a flood zone, encapsulation is not possible for us. Next time, if I can’t do a drive under, I’ll probably go with a raised slab.

[billybek]

My FIL had his summer house done.
I was down in the crawl space last year repairing a leak from the dehumidifier and the bottom of the flooring and beams were sprayed with some type of foam.
Dehumidification was key and the the dehumidifier was a pretty robust looking unit that drained into the sump pump.

[69porsche]

Originally Posted by A930Rocket

What part of Charleston are you in?

Being in a flood zone, encapsulation is not possible for us. Next time, if I can’t do a drive under, I’ll probably go with a raised slab.

I am over in Wadmalaw Island and my neighbors have their crawlspace encapsulated- I can see the benefits of it and right now getting estimates.- Ideally I would like to get the house completed no later than end of June. This project is competing with other projects so I am trying to nail the ideal timeline.

[Mike Andrew]

Had ours done 2 years ago and some foundation cracks fixed & new windows at the same time. Cost was about $2500 for the crawl and another $4000 for foundation repair and new windows. Seriously less humidity in the whole house and the white plastic makes it easy to see when I have to retrieve anything.
Side note: Emptying the crawl ahead of process resulted in a serious set of piles for Salvation Army, scrappers and the garbage guys. Man, does $hit accumulate over 25 years when it is out of sight.

[fintstone]

My vacation house had this done before we bought it and it seems to work remarkably well. Although the area is wooded and the humidity high, the home is not humid at all.

The house is on a hill and they installed a lot of drains above the house as well to reduce ground water/soil moisture. The big dehumidifier still pumps out a lot of water.

[69porsche]

Originally Posted by madcorgi

Gordon,

I used to own a company that did crawlspace encapsulation as one product offering. It's the real deal--we started by laying down drainage mat, then covered it with 20-mil fiberglass reinforced plastic sheeting glued together. 10-mil plastic went up the sides, glued and pinned to the concrete walls just below the floor joists. We'd then hang a permanent set-and-forget dehumidifier from the joists, set at 50% RH, with an outside drain. For chronically wet spaces, we'd also install a sump system, or integrate an existing sump into the system. We guaranteed the work against water intrusion for 25 years.

Besides reducing indoor air pollution (50% of the air you breathe is from the crawl, including vapors from whatever is living down there, peeing and pooping down there, and dying down there), it also controls interior RH. In houses with moisture problems that cause the wood flooring to get wavy, the system can reduce RH to the point where the flooring sits flat again. And indoor mold growth can also be better controlled (mold does not grow at less than 60% RH).

I arranged to have all the local west coast installers become certified by installing the system at my house. It changed a dark, dank crawl into 1000 sq ft of usable space. The plastic is white, so it looks like an operating room down there. Really a nice upgrade.

The process is called AdvantaSeal, and the company is AdvantaClean. In Charleston, the local AdvantaClean is run by a friend of mine, Mario Colangelo. I know that he does a lot of these.
https://www.advantaclean.com/charleston-sc/ He's a great guy, and can give you all the details.

Thanks! I reached out to his company and will have site visit