How to eliminate mold during home rehab?
April 19, 2010 10:46 PM   Subscribe

Mold -- Is it possible to eliminate mold as part of a home rehab project without hiring an all-out mold professional? Will it be sufficient to remove all the drywall, scrub and bleach the wood behind (or replace anything damaged), and stop the sources of water intrusion? Did you deal with mold as part of a major fixer-upper?

The house I bought has mold across some lower sections of drywall in the ground floor level (18" below grade, with past flooding). I have a major rehab budget that involves demo of all the drywall and replacement of anything water damaged, but I'm now wondering if it's worth hiring an all-out mold abatement specialist to be on the safe side. Unfortunately, the cost of the abatement specialist would have to come out of my limited contingency budget or very limited cash on hand. So I should only do it if it's really necessary.

On the one hand, I have the sense that you really don't want to ignore mold, but on the other, even the local mold specialist said that much of the mold panic is somewhat like all the nightly news exposé fearmongering. ("WILL TOXINS IN HONEY KILL YOUR CHILDREN?") So, I want to be cautious but not go overboard.

From what I understand, the best practices for mold removal are:
- eliminate the sources of water
- take caution not to spread mold spores everywhere during demo
- replace wood or drywall damaged by mold
- treat surfaces that might have mold "roots" in them
- keep the area dry over time

The general contractor is planning to install a french drain, replace the brick foundation on the uphill side with a concrete foundation, and replace the roof, so water intrusion should be contained. He will demolish the drywall, replace damaged wood surfaces, and (in my limited understanding) scrub and then sterilize other wood surfaces with bleach. All the mold is contained to one level, and as all the drywall and carpet throughout is getting torn out, I'm not sure how serious a threat is posed by cross-contamination, but I can definitely ask them to be careful during demolition.

For comparison, I called a mold professional, and it sounded like if I'm willing to pay $5-8k, I could have this person do the demolition behind ET-esque plastic sheeting with negative air pressure; scrub the wood with some sort of rotating wire brush (my current contractor might use that as well); apply some other (non bleach) special mold-killing solution; and paint all the wood with some anti-microbial paint that has a 5-10 year anti-mold warranty associated with it.

Do you think it's worth it? Why? As a middle ground, do you think it'd be possible to get that warranty by working with my current contractor to use the same techniques and paint? Any other advice?

Part of me thinks I'm just being a neurotic perfectionist (as usual) and should just leave this to the contractor, who has apparently dealt with mold in various rehab projects. Still, since it could be a big deal, the other part of me thinks I should spend the extra money to ensure no future worst case scenario. If money was no option, I would definitely do it, but spending that extra now would mean using money from my contingency budget early in the project instead of saving it for other emergencies. It would really help to have additional thoughts and input. Also, if I could make one more request, I'm really sort of nervous about this, so I'd really appreciate it if people could skip comments like "you're totally screwed" and move straight to advising me how to ensure I'm not.
posted by slidell to Home & Garden (13 answers total) 5 users marked this as a favorite
AFAIK it depends on what kind of mold you have. I had some mold in my house when I bought I because the roof was leaking for years. It wasn't exotic kill-you-in-your-sleep mold so on the advice of a bunch of people I just fixed the roof, replaced the drywall and a couple of water damaged sills and studs and called it good. So far no problems at all. The house is very dry now that it has a functional roof (forced air) and the kind of mold I had needs water to grow, similar to mildew. I think the really bad kinds don't necessarily need much water because they seem to do OK in places like LA where houses are typically pretty dry.

If you had groundwater flooding in the past (like a river came through the house) or a leaky toilet you may have more exotic mold and/or other issues due to the organics and other contaminants and it may warrant more extensive cleanup from what I was told.

Anyway that was my experience. I had a house inspector and another inspector look at my place. Neither one of them was going to get the cleanup job so I felt they gave me honest answers. They didn't seem concerned about it at all.
posted by fshgrl at 10:57 PM on April 19, 2010

from all i've heard, mold is one of those things where you just dont buy the house...i.e. a total nightmare...honestly, i'm surprised that 5-8K is all that's required to take care of it. do they replace the walls in that estimate? (i'm assuming they have to come off)...sounds like a pretty good deal, actually. if you're the handy type, you might offer to pitch in to get the price down (at least with the wire brush part...even with the drill that sounds time-consuming= $Labor$)...that negative pressure set-up might be something your contractor might not have, but you could always ask...
posted by sexyrobot at 10:59 PM on April 19, 2010

Do you have to identify prior significant mold infestations on the spec sheet for your house when you try to sell? (you might be obligated to do so). If so, perspective buyers may want to know how it was treated and the difference between "yeah I did all the work" / "This GC did the work" and "we had a professional treat and eliminate it" could be significant. Also something to check on is if building codes in your area require licensed specialists to treat this problem.

From a purely "can I physically do this" aspect. I highly suspect you or your GC could do it, and do it well, likely without serious health risk (don't sue me if it turns out not the case). BUt if you do decide to DIY it, use a respirator and GOOD ventilation.

I would get it taken care of one way or the other, as while I expect the risk may be overplayed, it is a real risk that accumulates over time, especially in the younger population, or those susceptible to such things.

(unless the paint is geared only towards professional use/application and requires specific techniques I'd think the warranty would be good no matter who uses it. I've used anti-mold/mildew paint in numerous situations as a preventative)
posted by edgeways at 11:03 PM on April 19, 2010

Response by poster: One clarification: I'm not thinking that I might DIY this. Either the GC will handle it (within the scope of the current contract, so it wouldn't cut into the contingency or cash budgets), or I will pay extra to have a mold abatement specialist handle do it. Most of all, I'm trying to figure out if the difference in their methods is significant. Could the GC do a "good enough" job?

sexyrobot, if I were to consider backing out of the deal at this point, I would lose half of my downpayment and a house that is probably a really good deal even after paying for all of the repairs, so it's not that I couldn't decide to do that, but I would need a really systematic way to justify that decision to myself that I could carry out in the next 48 hours.

I really like the testing suggestion -- one possible way to know more about what we're dealing with and therefore how much money and effort I should put into abatement. (I'm now kicking myself for not testing the mold species earlier, but ... too late.) The resale and building code considerations are also very helpful.
posted by slidell at 11:18 PM on April 19, 2010

The negative air pressure system the specialist would use will do an excellent job of containing the mold spores released during the demo. I think that without containment, you run the risk of seeing the same mold crop up again, the next time there's any humidity or dampness.
posted by zippy at 1:31 AM on April 20, 2010

Treatment by a specialist is good - there are different types of mold and knowing what you're dealing with is important. At least get a sample identified of the different types of mold.

A couple of quick thoughts:
The mold remediation specialist should work in conjunction w/ the GC so their work is coordinated.

At least pay the specialist to determine the course of action. The GC (or you) may be able to do the work. But, you need that expert opinion first. And, consider as mentioned above how the resell value will be impacted.

Rather than wire brush removal look into a type of pressure washing that's done w/ dry ice. If you're doing a total gut job, you can use sandblasting.

Use mold resistant drywall on the remodel.

Mold needs humidity + food + warmth to grow. Eliminate at least one of those sources, preferably two.
posted by mightshould at 4:04 AM on April 20, 2010

I think you might want to investigate the best mold killing agents. I think the pros use an alkyl based solution rather than bleach.
posted by caddis at 4:16 AM on April 20, 2010

Molds are not nearly the "OMG WE'RE ALL GONNA DIE!" thing that some people have been led to believe...usually by other people who have a profit motive in making them believe it. Here's the CDC on molds, including the "deadly" black mold.

What your GC proposes is probably more than adequate to deal with the problem. You can ask them to use the blocker paint if you're concerned. It shouldn't up your current estimate by more than a hundred dollars or so.

For the record, insurance companies are no longer condemning properties with mold, as much research has proven that the problem can be solved. As well, even in those few states with mold on the property disclosure forms, only *current* mold infestation is required to be reported, not treated and solved mold issues.

Unless you have severe mold allergies and are living in the property while the renovation is being done, you probably don't need to pay the specialist. (Which is to say, were it me, I wouldn't pay the specialist because the GC's plan will solve the problem.)
posted by dejah420 at 6:10 AM on April 20, 2010

Response by poster: I scheduled a mold inspection for today at 2 by Bay Area Restoration Services. How do you know which companies are better than others? I couldn't find them on Yelp, but then, who Yelps about their mold inspection? Results will be available by tomorrow at 6 pm.
posted by slidell at 9:08 AM on April 20, 2010

We encountered mold during a flood rehab of our home in Houston Texas. Of course, Houston is 45% mold anyway, what with the humidity. We pulled up drywall and killed all teh mold we found until we stopped seeing mold and we were satisfied that we covered all the formerly flooded areas. The contractor sprayed mildewcide to prevent spreading and used "Outdoor Bleach" to kill the mold we could see

Mold is not the end of the world and not cause for panic and trepidation, though prudent and timely action is needed.
posted by cross_impact at 11:29 AM on April 20, 2010

Our GC (eco-mod specialist, not a cowboy) is in the process of doing this right now, and didn't seem to think it was a problem. He's just taking sensible precautions - masks, plastic sheeting, etc. We've identified and repaired the cause of the leak, and the affected wood is being scrubbed down and/or replaced (god bless wood paneling!). If you're concerned about it, find a mold specialist who is willing to come do a (paid) inspection and recommend best practices - without trying to give you the hard sell.
posted by media_itoku at 7:34 AM on April 21, 2010

Response by poster: media_itoku, how large an area was affected?

The inspector did seem pretty concerned. I actually don't know how to get good advice on this because the inspector did want to sell me on their remediation services. (I told him that I wouldn't be doing that, right up front, but it didn't really sink in.)

I'm feeling pretty confused at the moment. GC says he can do it, mold remediation guy says that would be a mistake and that it does appear to be a more serious kind of mold, the Internet is full of health scare stories, and I'm even wondering if it's such a big problem I should walk away. Any sources of good info or advice would be very welcome...
posted by slidell at 8:04 AM on April 21, 2010

Response by poster: Good advice beyond this, that can be more targeted to the specific details of my situation, I mean. I really appreciate these comments, which added a lot to my thought process. Thank you.
posted by slidell at 8:10 AM on April 21, 2010

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