Mold Removal and Crawl Space Q&A Cleaning up mold growth and spores with dehumidifier, vapor steam cleaner, air purifier Answer

From: Fred R.
I have a new addition to my home - about 1,900 sq.ft. of crawl space. The crawlspace is approx 44" high from the bottom of the floor joist to the top of the stone base floor. The crawl space is well vented with foundation vents and I have 6 mill visqueen on the dirt floor covered with 4" of crushed gravel. I also have two sump pumps.

The problem is that during construction, the floor got wet and there is some white and black mold on the floor joist and the underside of the floor sheathing. My thought is to dry out the crawl space and the mold will go away before it gets too bad. Would a dehumidifier work for this problem or do I need to force some more air circulation under the house with fans?
Thanks for your help,

Hi Fred,
Getting the humidity under control will help your mold problem but not eliminate it all together. The mold will remain active as long as the humidity remains high usually 60% or higher. Therefore, if you lower the humidity with a dehumidifier to 50% and maintain it there, the mold will become inactive and not get any worse. However, it will not die and disappear and it will still emit mold spores. For this reason, it would be beneficial to eradicate the mold by cleaning it up and removing it. There are several ways you can do this. First, you can kill the mold with heat by using a vapor steam cleaner. This is a dry vapor steam at 180 to 220 degrees, which will kill most mold. Keep in mind, there are many different kinds of mold and some of them are heat resistant. Second, you can spray a solution of tea tree oil and water approximately 2 teaspoons to 2 cups of water. The only problem with this method is that the smell is very strong and tea tree oil is expensive but a little goes a long way. Third, grapefruit seed extract or citrus seed extract and water can be used. You mix 20 drops of citrus seed extract with 2 cups of water and mix it in a spray bottle and spray on the problem areas. Do not rinse. Fourth, you can use straight vinegar in a spray bottle and apply it to the problem areas and do not rinse it. This is the cheapest method but like the tea tree oil the smell is very strong.
I would caution you to be careful when cleaning up mold. I recommend you wear a mask to prevent your inhaling the airborne mold spores that will be present especially when you disrupt the mold. Also, you should isolate the area as much as possible so the mold spores cannot circulate to another area of the basement where it can begin to develop in a new area.
In answering your question as to whether or not it is helpful to run fans, this is a good idea because when there is water in a liquid state it will aid in the evaporation of the water and then the increased humidity caused by the evaporation should be removed with a dehumidifier. In addition, mold likes a dark environment with no air movement to develop so circulating the air with fans will discourage its development.
Keep in mind there are three things necessary for mold to grow. You need mold spores which there will always be a supply of because it is in the outside air and infiltrates inside to your home. You need a porous surface for the mold to feed on like wood, wall board, etc. which we all have. The final thing needed is moisture with humidity 60% and higher. This is why if you eliminate any moisture and control the humidity with a dehumidifier, you will not develop mold. Keep in mind, you will still need to remove the mold you already have.
Based on the dimensions you gave me, you would need to remove approximately 38 pints of moisture per day to maintain a relative humidity of 50%. If the average temperature in your crawl space is always above 66 degrees you could consider the for $299.95. For temperatures down to around 52 degrees the for $259.95 would be appropriate.
Besides a dehumidifier, another way to prevent mold from redeveloping would be to remove the mold spores that are airborne. This is normally next to impossible especially if there is mold already present in a particular area. However, assuming the mold in the area will be removed eventually this can be accomplished over a 4 week period through the use of a fairly new product we have on our website. It is called the . The way it works is the mold spores enter the air sterilizer through convection where they go into a chamber where they are incinerated at 400 to 600 degrees. The air is then cooled and the sterilized air is emitted back into the room. Slowly over time the amount of mold spores in the air will be reduced down to zero and by leaving the unit running continuously, any new mold spores introduced into the air will be removed. The net result is if conditions arise to encourage the formation of mold like water or excessive humidity, mold will not develop because you have removed one of the three things necessary for mold to develop. In your case, you would need 4 of the units because one of these units will sterilize an area of 250 square feet with a ceiling height of 8 feet, which is 2000 cubic feet. You have approximately 7600 cubic feet so 4 units would be recommended. The nice thing about this unit is it is completely quiet and there are no filters to change and zero maintenance. The electrical usage is like a light bulb so it might cost you a couple of dollars a month to run one of these.
I have a few websites to give you where you will be able to get additional information on mold removal.
At our own website

World Wide web sites

One final note, I failed to mention to you that the most important thing to do when you have mold is to consider the source of the mold to begin with and make sure the reason for the mold occurring in the first place has been remedied. It sounds like you have already taken care of this based on the fact the mold was a result of water leaking during construction.
Please feel free to contact me to discuss any of the products we offer from our .