I am currently building an ICF home with an unvented crawlspace. The house is “dried in”. The crawlspace is only 3 ft. at the lowest point and 8ft. at the highest. In the highest corner I currently have an uncovered opening that will have a garage door installed in it later, roughly 6 ft. by 6ft. The crawlspace has continuous drainage around the perimeter suitable for a basement and has had it since a few days after it was poured. We did have quite a bit of rain during the time it was framed, before it was dried in. I have had no visible water in the crawlspace since dry in. I noticed today for the first time that the soil is extremely moist, almost muddy. There is also mold forming on the sides of the joists and on the underside of the subfloor…a significant amount. I even have it forming on the sides of the beams…more on that in a minute. Here’s my problem. I currently don’t have my vapor barrier installed but obviously will eventually. When should I do it and in what order? It’s a spec that’s for sale and I’m afraid the mold might scare someone away. Can I get rid of the mold first? How? My intention is to have continuous vapor barrier and a dehumidifier that discharges outside the crawlspace. The HVAC (heat pump) will be a split unit with the airhandler in the crawlspace. Should I go ahead and do the dehumidifier now? I have never had this happen before and have never seen it on a house under construction.
Here’s the real noggin tickler I referred to earlier. The mold on the sides of the beams is not continuous. Every 16 in. oc there is a 4″ wide area that has no mold. It falls in the exact center of the bays between where the I joists layout. Any idea why?
Replies
Get a dehumidifier or two going in there ASAP, worry about the 4" mold free area over a beer when the house is complete. Grainger can have a couple dehumidifiers on your door step in 24 hours.
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"You cannot work hard enough to make up for a sloppy estimate."
What about the vapor barrier? Shouldn't he put that down as well? I don't see why not. Unless you want dry out the soil a bit.
I'd dry it out first and then put the vapor barrier down. ------------------
"You cannot work hard enough to make up for a sloppy estimate."
That makes sense.
I am guessing that the moisture is coming from the ground, not the rain if you did not notice it before. If that is the case, I would put the poly down and keep the water from migrating up.
If you are having a dry spell and the moisture content of the air is low, maybe rent a commercial fan and circulate air in there to dry it out. Cheaper than dehumidifier and can be very effective if the ambient exterior moisture content is low.
Then call local mold company and get their thoughts on how to address it.
I have gone ahead and put a dehumidifier in the crawlspace in an effort to dry out the soil BEFORE plastic goes down. My intention always has been to install a dehumidifier as a "backup" anyway so there's no extra expense involved. I was holding off on the plastic for two reasons: 1) my electricians and plumbers can't tear it up if it hasn't been put down. 2) On my friend's house we put down the plastic before the house was dried in completely and we think in hindsight we actually trapped the excessive moisture that was present which in turn caused a lot of mold to form under the plastic. His house actually started to smell he had so much mold under the plastic. He never had any mold anywhere else. This was a big part of my motivation for leaving the crawlspace open and letting the soil dry before installing the plastic.
I'll keep everyone posted as to the results. I still would like advice on removing the existing mold once it dies. I live in a somewhat rural area of Tennessee and very few people here even try to deal with preventing mold, let alone removing it once it is there.
How's about if you had put down the plastic and run it up the side of the ICF and sealed it then put pea gravel over the plastic so your electrician and plumber could work there in ease and not rip the poly.
How do you know it's mold? Are you an expert on the subject? My point is if you know it's mold and have it identified by an expert, then you should disclose that to the potential buyers.
It may be mildew, but I'm no expert.
I would clean the joists with a bleach and soap solution and then use a borate like Tim-Bor which is available on the internet if your local supplier won't sell to you.
Perhaps a rat slab on top of the plastic is in order.
Kurt
http://www.traskresearch.com
"Every 16 in. oc there is a 4" wide area that has no mold. It falls in the exact center of the bays between where the I joists layout. Any idea why?"
Yes - the mold spores were on the I-joists during/before construction and were lodged in the rough surfaces (also attracted to glue, etc.). The I-joists may also be capable of holding more moisture than the subfloor.
Jeff
Another update...unless I'm crazy the dehumidifier is already having an impact. I've had it running all day. It's a Whirlpool from Lowe's that I've set the fan on automatic and the humidistat on "very dry". I can no longer see any "mold" on the sides of the I joists. It's now only on the sides of the beams (and even those seem to have less) and on the underside of the subfloor. I just completed stapling some 6mil to the inside of my basement garage door opening to seal the thing up a little tighter. I'm thinking this should prevent dehumidifying the planet. I'd like to address two issues brought up earlier. 1) Is it mold?-I really don't know for sure. It's looks like the little fuzzy green/grey spots that grows on my bread if I don't eat it fast enough so to me it's mold. I honestly don't know the difference between mold and mildew so to those who have far more knowlege on these matters than I please forgive me for using the word mold in such a generic fashion. I meant no harm. As far as disclosure to potential buyers-that's an interesting subject, perhaps even worth of a completely different discussion. I will handle it this way. If I am able to successfully deal with the humidity problem, kill the existing mold, and see no reappearance of mold in the weeks/months leading up to completion then no, I won't disclose to a potential buyer that I saw mold during construction. If I saw a termite before I treated for termites should I disclose that as well? I think not. (I didn't by the way) If by some far off unbelievable turn of events I am unable to eliminate the mold...then drop to your knees and start praying because the earth will be about to spiral off of it's axis and tumble toward a fiery demise in our sun...and also yes, I would disclose it to any potential buyers. I live in a small town where reputation means everything. How a person handles adversity says an awful lot about what kind of person they really are.
Mold has all but disappeared and without any scrubbing. I'll be adding plastic soon.
I suggest that you dig down to the same level outside the house and find out where the water table is. If it is higher than the crawl space you will always have mud. The solution for damp ground that I have seen for crawl spaces is 6 mil poly taped and then spread 1500 psi concrete on it. We call it ground seal and it's about 1.5 " thick. Then cross vent the crawl space if the humidity level is above 60 % relative humidity. Mold can be killed with any household bleach at about 1/2 cup per gallon water. I would avoid a permanent dehumidifier as they require draining and are noisy and break down. They also don't work below 60 degrees F. I live in a house with a clay basement floor and have been fighting with this problem myself. The solution seems to be airflow.
Yea - you need to get rid of the mold ASAP. People really overreact to it these days. If a realtor sees it, you can cross that sale off the list.
I too am in favor of getting the soil as dry as possible before putting down the plastic. Another reason for not putting the plastic down until near the end of the construction process is that the subs will mess it all up, and you will find yourself redoing it.
On the houses I build they normally get dried in pretty quickly so these things don't happen very often. I had one about 5 years ago that got very wet thanks to the plumber. We had fans running for weeks trying to get that crawl dry. Also, some time ago here we had a discussion here about drying out houses and some guy chimed in who was actually a fire restoration specialist (or similar) and he told us about some kind of super dehumidifier that you can rent. Not actually a dehumidifier at all but I think it was called a desiccant (sp?) machine.
You can apply straight chlorox from a garden sprayer to the soil to help kill the mold. Clorox is cheap. The problem is that this task is a very nasty one that I wouldn't wish on anyone. When I did mine, I set up a fan to get some air changes going and then started at the back and only did about as much as I could while holding my breath, then ran out for some fresh air. One of those air tanks like the firemen use woulda been the ticket. I had a helper there with me just in case.
Really though it takes 3 things to grow mold - 1) moisture, 2) air, and 3) organic material. You have to remove one of those to really get rid of it. You can't do anything about the last 2 so the first one is the one you have to address.
Since you already feel like you may have a moisture issue you may want to look into an upgraded vapor barrier like Tu-tuff (sp?).
Either that, or make darn sure that the regular 6mil black poly is installed very well - with significant overlap. I'm not sure what you might be able to do to glue seams and wall connections but the idea would to try to make it more waterproof. It's difficult to find stuff that sticks well to regular poly.
Just out of curiosity where do you live that you can feel confident at building an ICF spec house?
Why no mold between the I joists. Possibly because there a bit more air circulation there.