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Removing mold in crawl space floor joist

Erich's picture

I have some black spots of mold on my floor joists in my crawl space.  The floor joists are insulated with fiberglass, and there is some mold on the fiberglass also.  This makes it hard to wipe-off the mold.  How can I get rid of the mold - what chemicals do I use?  Note - I have added a 6 mil vapor barrier, installed a dehumidifier and closed the crawl space vents.  This has helped and no new mold is growing.  I still need to get rid of the "old mold". 

(post #110736, reply #1 of 5)

You are going to have to remove and dispose of all porous materials containing mold.  Non-porous surfaces may be cleaned with a one part solution of clorox mixed to 10 parts of water.  Now, here is the hard part.  You may want to get professional help.  A professional will have the proper personal protective equipment such as latex gloves, protective clothing, eye protection and an organic vapor respirator.  They will also isolate the area with plastic sheeting and exhaust fans.  The mold and the strong clorox solution is harmful to people, especially the young, the old or others susceptible to illnesses.  Some of the molds are very toxic.  Mold needs food and water to grow.  The food is cellulose (wood, paper, sheetrock paper, etc).  Find out where the water is coming from and stop it.  if you don't the mold will come back.


There are two excellent web sites to check out.  One is from the EPA and the other is from New York City.  I will need to get the sites from my work computer on Monday and will send the links to you in the evening.


I am not qualified to do mold remediation but do perform investigations to find and classify mold.  I am not telling you these things as recommendations for you to do the work.  Rather, it is to educate you on the process so that you can better decide what you are going to do.  Please check back Monday evening.  Also, you might check with your insurance company but be prepared as some companies are now excluding mold from their coverage.

(post #110736, reply #2 of 5)

Thank you!!  On the floor joists - can I just spray the mold with the bleach solution,  or does it have to be wiped off or vacuumed?  I have the protective equipment and sprayed the mold with bleach a few months ago, and things seem to look better.  I am putting in a foundation drain to keep moisture out.

(post #110736, reply #3 of 5)

It seems like you're on the right track. Do all you can to keep the area dry and spray thoroughly with a bleach solution. Once things are dry, little new mold should grow. Beyond that, I wouldn't worry about it. This isn't living space and the joists aren't rotting. Next project!


Al Mollitor, Sharon MA

(post #110736, reply #5 of 5)

I do not do the remediation, only check for the presence of mold - both dead and live.  When we do a mold investigation, we check for both live and dead molds(different procedures).  After remediation, we go back and do a clearance check.  if the old mold had not been wiped up, we would still find it in our air samples.  Even dead, it might cause allergic reactions to some people.  I don't know what else to tell you about leaving the dead stuff in place.  incidentally, the 10% clorox solution should be 1 part clorox and 9 parts water.  My mistake.  Again be very careful with it as its fumes are bad for folks too.  As far as vacumming it up, unless the vacumm is one made with a filter that can trap the small mold fungii (HEPA), I woul think it would tend to really blow things around which wouldn't be to good.  Hope this is of use.

(post #110736, reply #4 of 5)