moisture in crawl space - navigating my options

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kimma
Posts: 1
Joined: Thu Sep 29, 2011 12:06 pm

moisture in crawl space - navigating my options

Post by kimma »

I have a home built in (very humid!) Atlanta in 1950, and expanded in 1970, so it's on two dirt crawl spaces. We're having issues with moisture in one specific area of the newer crawl that shows up after heavy rains - we notice because of a strong muddy smell (and sometimes a mildew-y smell follows that). We've gone under to look when the smell is there, and there is moisture that seems to be coming through the brick. We've never seen puddles of standing water, but there is mud splashed on the walls, so that suggests we may have had some puddles in the past. The ground on the outside of the house in that area is shady, and tends to hold moisture (there is moss growing there) but it slopes away from the house. We have gutters that we haven't always done a great job of keeping clear.

The older crawl does not have a vapor barrier at all, and is powder dry. The newer crawl has a 6 mil vapor barrier, but it doesn't cover all of the ground. There are vents for both crawls that are just open year round, covered with mesh - I don't think they can be closed. We have a new, expensive HVAC unit installed in the older crawl. There's no insulation under our house at all (sometimes I can see sunlight through the floorboards near the vents!), but I think that's a whole 'nother issue.

We've had 6 different companies come out to look, and each has a very different answer for us, at very different price points. I think we've got a consensus that this isn't a major foundation issue, and that while there is some mold and mildew in the crawl, that it's minor and isn't going to require any real remediation effort.

The options that are seeming the most sensible (er, cheapest) to us are to either:

option from contractor 1 - install a french drain to lead water away from the problem area, and then install a 6 mil vapor barrier in on the ground only in the crawl, and leave the brick uncovered. (cheapest quote)

option from contractor 2 - lay a thicker (12 mil) vapor barrier on the ground in the crawl, and run a thinner (10mil) vapor barrier up the brick, so that the entire crawl is covered up to the wood beams. (second cheapest quote)

But we've also had a contractor tell us we don't have a problem at all, one suggest we need a dehumidifier / air exchange system installed, one suggest we need total crawl space encapsulation, and one suggest we need $20k of foundation repair. No one seems to be on the same page about what to do! And I'm out of contractor referrals, and the internet is failing me.

Anyone dealt with this kind of thing, or know anything about it, or know where I could turn for advice?

s.kelly
Posts: 652
Joined: Sat May 02, 2009 9:42 am

Re: moisture in crawl space - navigating my options

Post by s.kelly »

Most of the building science people these days are trying to bring the crawl spaces into the conditioned spaces of the building. Sounds like that is what quote number 2 is leaning in the direction of.

I am not sure if the second one also has a french drain. I am partial to the idea. Water is the enemy of a foundation, and I cannot think of a reason a french drain could hurt as long as it is done correctly. And it should help with moisture in the crawl. But they are not cheap. Looking at digging one in the alley beside my house next year.

downtowndahlgren
Posts: 398
Joined: Thu Jun 30, 2011 12:57 pm

Re: moisture in crawl space - navigating my options

Post by downtowndahlgren »

My house has a conditioned crawl space. All of the former vents are sealed; the dirt floor is covered with a special liner that seals to the sill plate. The space has a dehumidifier which empties into a sump pump with a battery backup, which also empties the groundwater that rises up underneath since I'm only a few blocks to a river. Before the system was installed the beams had sagged due to moisture and had to be jacked up and supported with piers; plus there was standing water and a horrible musty smell underneath the house. Now it is bright, clean, and always less than 45% humidity, which prevents mold and mildew growth. One of the most expensive, but best home projects I ever did.

s.kelly
Posts: 652
Joined: Sat May 02, 2009 9:42 am

Re: moisture in crawl space - navigating my options

Post by s.kelly »

I installed an elevator in a house on the Northern Neck some years ago. The machine room was in the crawl which was a conditioned crawl. So nice!

My house is attached to the neighbor, so to make the crawl conditioned space would mean building a wall first :shock:

Probably not going to happen, but if I get bored you never know.

Danno
Posts: 2549
Joined: Tue May 30, 2006 4:25 pm
Location: Hamilton, IL

Re: moisture in crawl space - navigating my options

Post by Danno »

Verifying proper grading and doing #1 is where I'd start. If you do the second option without stopping the water then you are just gonna ruin your brick foundation. It needs to breath and not be moisture logged.
1858 Italianate and Gothic Inspired thingamabob
HappyInHartwood: "You can't make something 'more' ruined."

downtowndahlgren
Posts: 398
Joined: Thu Jun 30, 2011 12:57 pm

Re: moisture in crawl space - navigating my options

Post by downtowndahlgren »

The only problem I can see with a french drain is that Kimma already said that the land is graded away from the house, and a french drain may not deal adequately with ground water that rises directly under the house, especially if the vapor barrier does not completely cover the entire surface of the affected crawlspace. The gutters also need to be cleaned out regularly, or good impermeable gutter guards installed, and the downspouts emptied at a good distance from the foundation. The concept of sealing and dehumidifying a crawlspace was developed in South Carolina, so it would be useful in Atlanta as well, I would think. Even if you don't get the full encapsulation, which might not be appropriate with brick, having the humidity significantly reduced in the crawlspace will help with the mold and mildew.

triguy128
Posts: 708
Joined: Mon Sep 12, 2011 9:41 pm
Location: Keokuk, Iowa

Re: moisture in crawl space - navigating my options

Post by triguy128 »

Aother optoin could be to used close cell spray foam under the floor, then vent the heck out of the space. It seems like sealing it up would be the best solution however and get a vapor barrier over the dirt the seal and insulate the perimeter.
1925 Neo-Classical

Previous home - 1968 single story Ranch/Colonial, 1200sqft - 11 windows
Current home - 1925 2 story Beaux Arts Neo-classical overlooking the Mississippi River, 3200sqft - 48 Windows

KristinM
Posts: 3
Joined: Fri Sep 30, 2011 11:15 am
Location: Knoxville, TN

Re: moisture in crawl space - navigating my options

Post by KristinM »

Hi, I'm a long-time lurker but first time poster because my 1920s craftsman is mid-renovation and not quite ready to post pics of yet, but I was encouraged to chime in because I actually work for a company that specializes in closed crawl spaces and moisture control. If you haven't yet, you might want to get in touch with CrawlSpace Care: http://www.crawlspacecare.com/find_a_dealer.php

They're a South Carolina based network of certified installers of closed crawlspaces. If you're even slightly handy, the products are also available to consumers for DIY purposes here: http://www.crawlspacedepot.com/ You'll knock a couple grand off the cost if you do it yourself. I've watched them install it and it's really not very difficult at all.

I have nothing to gain personally or professionally by recommending them, but for the good of your house and not spending more money down the road fixing it again, I would advise that you talk with a company that specializes in this if you haven't already, rather than just a general contractor. Anyone can throw some vapor barrier down and say they're an expert, but CrawlSpace Care in particular has participated in government energy studies, is contracted through Habitat for Humanity to close all their crawl spaces, and has about a decade of experience under their belts. Closing a crawl space has the added benefits of saving you up to 20% on your heating and cooling costs, improving indoor air quality, and improved pest control.

Good luck! Let me know if you have any questions!
Image

1920 craftsman bungalow
Knoxville, TN

Danno
Posts: 2549
Joined: Tue May 30, 2006 4:25 pm
Location: Hamilton, IL

Re: moisture in crawl space - navigating my options

Post by Danno »

All this talk of vapor barriers and wall linings, etc has my BP up through the roof. Nobody has spelled it out, but let me go on the record with this statement:

Abso-freaking-lutely DO NOT put a vapor barrier, or a wall liner, or paint' or insulation on the INSIDE of your foundation walls (not talking floors here) be it a crawlspace or normal basement wall. There are only a couple exceptions to this, and they are for people who aren't reading old-house forums (ie poured basement).
1858 Italianate and Gothic Inspired thingamabob
HappyInHartwood: "You can't make something 'more' ruined."

KristinM
Posts: 3
Joined: Fri Sep 30, 2011 11:15 am
Location: Knoxville, TN

Re: moisture in crawl space - navigating my options

Post by KristinM »

Danno -

Because of condensation concerns, it's standard practice when closing a crawl space (at least among people who do it right) to install a French drainage system around the perimeter walls to address any condensation that forms between the foundation wall and the vapor barrier, plus a sump pump and a dehumidifier. Are there any other concerns besides moisture between the wall and liner? To my knowledge as long as the drainage and grading is good on the outside of the house this is sufficient to prevent any foundation damage. Correct me if I'm wrong though, I'm a non-expert relaying what I've heard from others. :)

Kristin
Image

1920 craftsman bungalow
Knoxville, TN

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