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Mold in Basement - Need Advice

Posted by firsthome (My Page) on
Tue, Apr 27, 10 at 11:08

We just discovered we have mold in our basement. The basement is an old finished basement with wood paneling. We removed a panel piece for electrical work and discovered mold on the drywall behind the wood paneling. I have no idea how long the mold has been there (we purchased the house 4.5 years ago). How much mold we have (we have only removed one section of the paneling so far). There are other areas that are not paneled and I do not see any mold.

My husband now wants pay someone to "get the mold out of our house" and refinish the basement.

My concern is to make sure we finish the basement correctly and do everything we can so the mold doesn't come back.

Basement details: Half the basement is a 4 foot high crawl space (the crawl space ground is covered in concrete). The other half is the "finished" basement section. Basement walls are cinderblock and I believe the floor is a concrete floating slab. The basement currently is finished with fiberglass insulation rolled between the wall framing (right up against the cinderblock wall). There is no vapor barrier. The floor has a thin low pile carpet with black foam backing epoxyed directly to the concrete floor (not happy about that).

Water in the basement has not been an issue. We live high on a hill with land sloping away from the house, gutters are cleaned 4 times a year, and downspouts point away from the house.

I beleive the issue is humidity, but I am not sure. Again, I don't know how long the mold has been there and if it was an old problem or if it still is an issue. The basement doesn't smell musty and the joists actually look splintered and dryed out. When we purchased the house the home had a 30+ year old furnice with a broken water valve that was shut off, so in the winter we had no moisture. It was really horribly dry. Since then we have purchased a geothermal system. Last night our hydrometer showed 56% humidty (April 27 - rainy day). We live in a very wooded area in southeastern PA.

When refinishing the basement what methods & materials should we use? Do we use a paint or XPS type vapor barrier? Insulation? Floor materials? Drywall? Also what do we do with the crawl space area?

I would like not to have to run a dehumidfier. We are trying to be energy efficient (why we got the GeoThermal system) so I really don't want to have a dehumidifier running constantly. Is that possible? We don't run one now and I hate to have to do that. Plus since we never go down into the basement I would forget to empty it anyway.

I would like to make this an inexpensive project. We were not planning on finishing the basement. We really don't use the basement at all, but we purchased a house with a finished basement...so we don't want to de-value our house by ripping it out and not putting one back in.

Thanks in advance for the advice.


Follow-Up Postings:

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RE: Mold in Basement - Need Advice

Check out lots of past threads on these topics.

Just a few quick comments: 1) 56% rh is too high. Aim for under 50% as a max. 2) Get rid of fg on walls and rims (Ditto the moisture absorbing foam backed carpet.); 3) replace with XPS, EPS, polyiso, or cc spf followed by fg or cellulose to cut installation cost; 4) either seal the crawlspace or provide adequate venting.

Sorry, but mechanical dehumidification is a must. Connect it to a drain so you don't have to bother with constant emptying.

For the long form see: Building Science Corp research reports on basements.

Here is a link that might be useful: Fighting Mold: The Homeowner's Guide


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RE: Mold in Basement - Need Advice

Mold is a greatly exaggerated non-issue in most cases.

How you proceed depends upon the age of your house.

If your house was constructed before say 1970, it is likley that you have no damproofing foundation coating on the exterior walls of your foundation nor any plastic vapor retarder under the slab in the basement of the crawl.

This is significant because this is likely the source of your high humidity levels: ground water vapor entering the basement through the masonry foundation and the concrete slab.

Unless you damproof both, nothing else you do (short of dehumidifying) will work.

Your best and least costly approach would be to use vapor retarder coatings applied directly to the foundation and concrete.

Then refinish the walls with mold resistant drywall or fiberglass wall systems.

The type of insulation is largely irrelevant if you do not address the high humidity issue.

Conditioning the space by heating, air conditioning, and dehumidifying may be your ultimate and only successful solution, however.


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RE: Mold in Basement - Need Advice

It's true that damp proofing will slow moisture drive. But since the damp proofing is only below grade, it does nothing for the drive in the portion of the foundation that is above grade. Furthermore, when the warm air in the basement touches the cold foundation, condensation occurs. That's why any insulation against the foundation wall should be a type that is unaffected by moisture.

If exterior damp proofing followed by interior fiberglass insulation and drywall were the answer, then we wouldn't have the endlessly documented problems of mouldy finished basements across North America.

Basement FG mould
Fiberglass insulation below grade

Insulation is not a remedy for excess humidity. Air conditioning may help. But as houses become tighter, a/c is not used long enough to reduce basement r/h. For that, you need a dehumidifier.

Here is a link that might be useful: We Need to do it Different This Time


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RE: Mold in Basement - Need Advice

Well, we are in the finishing stretch ourselves.
We found in our house was perhaps black mold but I think we were being taken for a ride; however, we wanted to be on the safe side.
What was really going on?
We were able to find an air quality consultant $500 including air tests and 2 visits, great guy
Removing the moldy insulation from our 1,500 sq ft basement, sheetrock and clean all wood with bleach and other mold killers.
The first quote was $24,000 and the pushy jerk said you get what you pay forBy the time the 3rd quote came it was $1,600 for, yes one thousand six hundred even. Rick @ Rapco in Lehigh Valley was great! He promised a great job and gave a great job; I cannot say enough wonderful things about Rick. http://rapcousa.net/
Next we put a French drain in the interior walls of the basement, we used www.basements.com MidAtalantic DO NOT USE THEM big DISAPPOINT MENT AND VERY VERY EXPENSIVE $15,000. The had to come back so many times and still I have a poor job. The salesman was very convincing and promised the world. There was only me complaining and my losing sleep.
The biggest improvement was running 2 dehumidifiers, this keeps it dry. We have insulated and have not been considering mold is an issue since.


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