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Crawlspace mold


krazycatlady's Avatar
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04-13-07, 06:34 AM   #1  
Crawlspace mold

Sorry if this topic isn't in the correct area. If it needs to be moved, please do so.

We have, what I'm assuming to be white mold growing in our crawlspace but it's only in one area that I can find. We also have it in places around the outside of our house. (perimeter, near the block foundation and the outside edge of our deck) I've done lots of researching & reading but would still like some advice. First, we have crawlspace vents that are supposed to close automatically according to temp, but I don't think they do. I've never seen them closed. We also have a vapor barrier on the crawlspace floor. There's about a 3' minimum space between the floor joists and dirt. I've read where crawlspace vents need to be closed during humid weather. Is this correct? We live in east TN and it gets pretty humid during the summer and if the vents not closing in the summer is causing the mold, shouldn't we close them? Also, we plan on digging out the moldy dirt in the crawlspace. What can we use to kill what's left? Is the bleach mixture the correct thing to use? I've seen where it's not recommended anymore. Also, I was considering getting a dehumidifier to put in the crawlspace to help take out some of the moisture. Good idea?

Any tips are greatly appreciated.

 
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airman.1994's Avatar
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04-13-07, 12:24 PM   #2  
Yes close vents! Replace VB! Bleach is fine! Buy a good dehumidifier!

 
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04-13-07, 12:29 PM   #3  
I hate asking this, but are you 100% sure you are looking at mold and not efflorence?

 
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04-21-07, 01:51 PM   #4  
Our vents are evidently the temp controlled kind and I can't seem to find a way to close them. Can we just cover them with plastic or something?

Also, I can't seem to figure out where the moisture is coming from. One side of the crawlspace dirt is wet. Not muddy, just really damp. The only thing near this side is the holding tank for the water but it's not damp around it. It's damp a good 3 feet or more away. Other than that there is no source for condensation or leaks, unless it's the piping for our propane tank. All other areas are dry. I'm clueless on this one.

Our plans are to remove the vapor barrier, seal the vents, and use a dehumidifier. Should we run the dehumidifier on a regular basis, during high humidity? Any tips on this will help too.

Thanks so much for all the help.

 
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04-21-07, 04:06 PM   #5  
You must have a VB!! Run up the walls and overlap all seams by two foot. Put hard poly stiren in vents. Set a good dehumdifier to 50% rh and let it run.

 
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04-22-07, 07:25 PM   #6  
In the deeper south, I must, and have always disagreed with closing up a crawlspace, but that's the nature of the forum. The automatic vents you have close in the winter and open in the summer. Precisely what they are supposed to do. You want cross ventilation in the humid summer months to keep the stagnant air moving. In the winter, they close to help keep heat in and prevent busted pipes. Airman and I always disagree (friendly), but I felt you should have the other viewpoint.

 
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04-22-07, 07:45 PM   #7  
White, fluffy, crystalline deposits are efflorescence. These are mineral salts deposited by moisture that has passed through masonry.

 
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04-22-07, 08:00 PM   #8  
I take it that this is a well tank. if so yes it will sweat all the time there.
vents in the crawl space NO WAY. in the summer you just let in the warm moist air and that hit the cool V/B on the cooler ground and you have water all over.
if you dont have any duct work down there that you can put registers in . then yes Id get a dehumidifier to put in the crawlspace to help take out some of the moisture.
Might go to http://aboutsavingheat.com/crawlspace.html

 
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04-24-07, 05:49 PM   #9  
Not sure where the OP is located, but lets not forget codes. The Southern Building Code requires opposing evenly spaced vents on all 4 sides of the foundation. The cross ventilation keeps the nasty hot air y'all have been afraid of from settling in. Closing up a crawl space is inviting mold and mildew, and a humidifier would run constantly and only give partial relief.

 
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04-24-07, 06:16 PM   #10  
crawl space code is changing! Vents are a thing of the past!

 
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06-08-07, 07:18 AM   #11  
Thank you!

I just wanted to come back and say thank you for your help. Thank you!! I covered our vents with 4 or 6 mil plastic (can't remember which), took care of the water problem (downspout), bought a humidity detector and a dehumidifier. We ran it off & on for a couple of weeks but have been running it regularly the past week and a half. The wet section of the crawlspace is drying up and we went from a high humidity of averaging in the upper 70's-80's down to 63% this morning.

Obviously this is working. So once again thank you!

PS. Airman, as I was researching I found a site (can't remember which one at the moment) that states what you said. The building codes are changing.

 
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06-08-07, 06:44 PM   #12  
I'm glad you took the time to do the research for your self. These guys have a lot of good tips and thoughts. I primarily have been doing IAQ/HVAC work for the last 13 yrs so I see this stuff every day and am well informed of changes in the business. Every home is the same but different and we are glad you took the time to find out which way is best for you. What kind of dehumidifier did you buy?

 
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06-09-07, 11:50 AM   #13  
We always seal the crawl space. 6 mil poly on the ground. over lap it 2 ft and tape all seams. 2" to 3"insulation on the walls up to the joist. A R 19 block like in each joist space all around the home on the sill plate. Two small register outlets in the duct and one small return. To let air out down there and it works as a heat sink for you. My company has been doing it like this for over 40 years now and it works just fine

Might go http://aboutsavingheat.com/crawlspace.html

 
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