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jeep4dog 11-03-2011 02:17 PM

Crawlspace mold repair questions
 
I just found the site and this is my first post.

I also apologize if this is a bit long, but my better half is freaked out right now.

We closed on a house on Friday and we are having the airducts and all the vents cleaned today. (My better half has super bad alergies so we thought it would help). So the dudes are there to clean the vents and they find mold in the crawlspace. Not a big deal, its a crawlspace I expect it to have some craziness growing down there. I checked it out at lunch, it is some tiny mold specs in the floor joists. And part of the vapor barrier is missing. (We actually knew that when we purchased) The vent dudes also said it appears to be in the insulation. Again not a shocker since its a crawlspace and the house is 20 years old. And of course the vent dudes can clean it for me and put in new insulation for $6K. Goooo! That's not gonna happen. It's been awhile but I've done insulation work in crawlspace in the past.

Everything I've read says use a 50/50 bleach/water solution let it dry and then treat the area with a fungicide and/or a paint product to seal against future mold.

So my plan of attack is this:
-remove all the old junk the previous owners left in the crawlspace (shelves, scarps of wood, junk)
-remove old insulation
-clean mold from floor joist, posts, and cinderblock walls
-treat the joist with mold blocking product or fungicide? or both
-paint cinderblock?
-install new insulation
-remove and replace old vapor barrier with new
-try to keep moisture down in crawlspace, and air circulating

Sound good so far? Now I have some questions.

If the mold is in the crawlspace and caused by moisture how do I get it dry after the 50/50 treatment?
Since the crawlspace has cinder block walls and posts do I also need to treat those with the 50/50 solution as if they have mold on them?
After cleaning the cinder block walls do I paint and seal them? If so can anyone recommend a product?
The insulation in the crawlspace now us just regular fiberglass insulation, do I need to replace this with something different?
If I'm going to replace the entire vapor barrier, can I use the old one to catch crap from the cleaning and insulation R/R, and then yank it out?
Do I need to treat the new ground at all before installing the new vapor barrier?

jklingel 11-03-2011 11:01 PM

"Sound good so far? Now I have some questions.

If the mold is in the crawlspace and caused by moisture how do I get it dry after the 50/50 treatment? Depends on your environment, but if you put 10 mil poly on the ground, run it up the CLEANED blocks and tape/goo it there (Tremco acoustical sealant will likely stick well to the blocks. It is called Black Death, and sticks to poly well), that may do it. Open the place up and ventilate A LOT while you are under there. Any mold, and its treatment chemical, can't do you any good. If it is real bad, you may want to talk to a mold pro crew and at least get a pro respirator. My son had an allergic reaction to mold in a closet, and he almost suffocated; he barely made it outside to fresh air. His throat was closing up.

Since the crawlspace has cinder block walls and posts do I also need to treat those with the 50/50 solution as if they have mold on them? Why gamble? Hit 'em. 10% bleach is what is used to disinfect in medical facilities. More than that is wasting bleach. Some folks say just wash w/ soap and water, but it is cheap and easy enough to hit it w/ bleach too, IMO. BTW: Don't mix bleach and something w/ ammonia in it; the fumes may kill you.

The insulation in the crawlspace now us just regular fiberglass insulation, do I need to replace this with something different? FG batts are poor insulation. I'd use Roxul, and/or nail rigid foam to the floor joists, taping and gooing the edges (joints in the foam). Crawl spaces do best when conditioned (heated) if practical. Read on buildingscience.com.

If I'm going to replace the entire vapor barrier, can I use the old one to catch crap from the cleaning and insulation R/R, and then yank it out? Sure.

Do I need to treat the new ground at all before installing the new vapor barrier? I don't see the point, as I am sure the earth is going to do whatever it is going to do, despite what you do.

Maintenance 6 11-04-2011 07:03 AM

You are pretty much on the right path. You have mold because of a moisture problem. Most likely there is not enough ventilation in the crawl space to keep humidity levels below 60% (+-). You need to create some air flow to keep things dried out. Regarding clean up. Get rid of the old insulation. If it has been dampened, mold has set up shop in it. It's impossible to clean and really tough to dry. Scrub the mold off with a detergent first or sand it off. Then treat with a fungicide. Bleach isn't the best cleaner but is OK as a fungicide. 10% is enough. Higher concentrations can cause you more health issues than the mold. There are other commercial fungicides available such as quaternary ammonias and phenols. Whatever you pick, treat 12" past the last known affected area. Do not treat things that aren't affected. (Why spray a corrosive chemical onto things that don't need it?) Wear a true respirator (N95 with P100 cartidges) not a dust cup and wear safety goggles. There's not a lot of difference between Roxul and fiberglass as far as moisture and mold. Foam won't allow much moisture absorbancy, but needs to be covered because of fire/flame spread issues. The vapor barrier info on the floor of the space is good practice even if the space is vented. Fungicide treatment is different from applying a blocker/sealer. After your fungicide treatment dries, apply a sealer such as Kilz or Zinsser. This is to "lock down" any stray mold fragments or embedded molds that the fungicide may not reach.


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