Crawl Space - Mold, now what?

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THeres chemical you can spray that should kill it. Try chlorox first. But may have to go with commercial stuff.

Unfortunately, several segments of the OSB between the joists seem shot as the floor above this is tile and has started cracking. These areas have long running cracks now at what has to be between the joists.

I’ve tried to convince me there had to be backer board, but I can’t see it cracking/sagging like it has.

That has what spurred the contractor otherwise I would treat in place. The contractor has serious concern opening that space up and exposing the inside of the house, even though it is a real small area. It seems way overkill but I also can understand isolating it.

Agreed, but this issue is specifically for the crawl space, not the basement. The major contributing factor to the moisture has been the lack of yard drainage coupled with three downspouts terminating nearby rather piped away. That is corrected so I feel the moisture issue is addressed. My major concern was what am I about to get into by opening this area up to replace the subfloor and is a $5,000 crawl space encapsulation system the right move going forward.

It’s amazing to me the conversations this topic leads to when talking with potential companies - absolutely blows my mind that there can be such big differences in strategy to address a crawl space.

Dead mold spores are only dangerous if they are disturbed (during construction). Mold needs moisture. Install exhaust fans connected to a humidistat set to 60%. Kill the mold, kill the problem (unless you are disturbing it).

About a month ago my buddy had that white mold on the joists under his cabin. He had Servpro come out and they sprayed and scrubbed all of it off. There was still residual mold/musty smell in the cabin on the couches & mattresses. Servpro came back out and ran two air scrubbers for a week in the cabin & crawl space.

Unfortunately his homeowner's insurance wouldn't cover the $4100 bill because Servpro didn't take any 'before' pictures.

You can buy several professional grade products fairly easily so don't use bleach for a variety of reasons. Distributors like Jon-Don or Aramsco work with mold remediation companies so you might start with their websites.

The mold issue should be addressed as a small percentage of the population does have adverse health effects due to mold exposure. If no one in the home has any problems, you may be in the clear but better safe than sorry. Regardless, if you ever plan to sell the home, you have to get this corrected.

Mold spores are Fungi. That is to say, the mold digest the surface that it grows on as a food source. Mold can be cleaned from a surface and the surface can be treated to prevent further mold growth. However, that subfloor may have some rot issues. If there is a structural integrity issue with the subfloor or floor joists, they will need to be replaced.

To clean mold from a surface, you generally start from the least aggressive method and go up to the most aggressive method required to remove the mold. It is very labor intensive, unpleasant, and difficult to work in crawlspaces which is why many homeowners elect to hire a professional. Methods of removal include but are not limited to:

Handwiping
Brushing with wire brushes
Sanding with belt sander or orbital sander
Dry Ice Blasting
Soda Blasting
And so forth.

All persons working in the crawlspace should be trained and qualified to use PPE. This includes DIY homeowners as well as professionals.

Moisture is the key. Without moisture, mold growth will not occur.

The moisture content of the floor joists and subfloor should be less than 18%. The relative humidity in the crawlspace should be kept below 60%. Much of the advice you have been given in partially correct. If fans, will keep the humidity below 60% RH, you will be fine. If not, you may need any or all of the following improvements:

Vapor Barrier
Encapulation
Dehumidification

There is lot more to the science of mold and how it affects people but this should give you an idea of what you are up against.

Wick, that's what his insurance agent told him.

But you're right about it being an old problem. Cause was a rusted out steel fitting going out to the holding tank.

I had the same issue that was discovered on inspection before I sold my home.

I don't think mine was nearly as severe as yours. But essentially they found an area in the foundation that was letting water come in and was being trapped. So they mitigated the source, cleaned the mold with scrubbing and disinfectant and the installed a vapor barrier and replaced insulation as needed.

That ran me $1900 or so.

There are companies who specialize in thse mitigation solutions.

In any case, if the integrity of the wood is there, I would probably just clean/disinfect and vapor barrier and address the source.

Of course I don't live at that house...so who knows if the above solution provided sustained treatment.