Q. I have hundreds of gallons of water in my crawl space. I am still under warranty and told my builder I want the problem address ASAP.  They've been dragging their feet due to a slow subcontractor. Initially, before I purchased the home, I was told that the house was built on top of the water in the crawlspace.  They pumped it out with a sump pump and told me the problem was solved. I did not believe them, and made sure that during my annual inspection the inspector went down there and found out it had tons of water.  Can this cause mold? [April 19, 2005]
         A. You are in danger of losing your home to likely mold infestation. The crawl space water will cause high crawl space humidity and thus high mold growth on the wood support timbers [which may also be directly wet from the water problem] and the crawl space wood roof. Mold can then grow from the crawl space into the floors and walls above. In addition, airborne mold spores from the crawl space mold will travel in air currents to mold cross contaminate your entire house and its heating/cooling system. You must find a permanent solution so that there is NO standing water in your crawl space ever. You are going to need to do mold remediation of the crawl space mold. Learn the 25 steps for safe and effective mold remediation. You are going to need to mold inspect and test your entire house. Read mold inspection and mold testing to learn how.

        Q. I am preparing to start remediation on my 50 year old house in Napa, California.  The crawl space is about three feet high with a dirt floor.  The dirt floor has a light dusting of white mold.  I plan to do the following in this order.  I would appreciate your insights and any recommendations regarding my plan.  I hope to do the work myself. 1.)  Apply a fungicide (can you suggest a product) to the dirt. 2.)  Install Visqueen over the dirt and up the cinder block walls, attaching it to the sill plate. 3.)  Install fans in existing vents to improve airflow.  4.)  Improve drainage/grade along exterior walls. Does the dirt floor need to be dry (or somewhat dry) before I do this work?  There is no standing water. Also, what should I do with the existing sump pump?  Cover it with Visqueen?  Run the Visqueen up to it?  Remove it? [Feb. 22, 2005]
        A. You need to mold test the air of the crawl space, the air of each room of the house, and the outward air flow from each heating/cooling duct register to determine how widespread mold cross contamination might be from airborne mold spores traveling in air currents from the mold in the crawl space. Follow the mold inspection and mold testing tips provided at Mold Inspection. Be especially sure to carefully inspect the wood components of your crawl space for possible mold growth. You can use a low-cost Mold Home Remedy Recipes available at Mold Mart  The ground can be damp, but it would be nice if it were dry because dry substances absorb water-based fungicides better than already wet materials. Leave the sump pump in place to help in future flooding problems. The plastic ground liner should be on top of the sump pump. Your idea of attaching a plastic moisture barrier is good--use 6 mil thickness over all dirt and up the sides of the crawl space. Use a good plastic tape to join the plastic sheets together. Hold the plastic in place by placing bricks or rocks at key points on the plastic sheeting. Yes, anything you can do to change the ground contour and drainage to keep water out of the crawl space is extremely critical to the success of your important mold remediation and mold prevention project.  Fan installation is also helpful. Use humidistat-controlled ventilation fans that run whenever the crawl space humidity exceeds 50 to 60%.

        Q. I have a crawl space (dirt). I had a main water line break (Kitchen and Laundry Room). Pipes are fixed, but the house has a heavy musty smell now.  The crawlspace is pretty much dry now, but there is a white almost chalky layer to the dirt down there. How do I kill the mold? [Feb. 7, 2005]
        A. Crawl space mold can easily grow into the floors and walls above. In addition, airborne mold spores from the crawl space mold can travel in air currents to mold cross contaminate your entire house and its heating/cooling system by entering your open windows, doors, and fresh air intake of your heating/cooling system. If there is enough room to work in the crawl space, it would be a good idea to kill the mold growth in the dirt and any mold spores and mold growth on the timbers of the crawl space and the underneath side of the floor decking You can use a low-cost Mold Home Remedy Recipes.  Then, if possible, remove and discard the top layer of dirt containing the mold. Similarly, also remove any visible mold growths on the crawl space lumber.  Do these steps as part of the overall mold remediation process. You would also be wise to mold test the crawl space afterwards, as well as the entire house. Follow thorough mold inspection and mold testing procedures.

          Q. Most of my basement is a crawl space.  The floor is concrete.  The ceiling is fiberglass insulation with no face or vapor barrier.  Should a plastic barrier be put up on the ceiling of the basement? [November 25, 2004]
       

         A. Your having a concrete floor [especially if there is an intact, functioning moisture/water barrier beneath the concrete or plenty of waterproofing compound mixed into the concrete] helps to prevent crawl space mold. If there is already mold growth on your crawl space ceiling, it will need to be first killed and removed. Follow the recommended steps for safe and effective mold remediation. Whether you have to do mold remediation, or the area is still mold-free, use a low-cost Mold Home Remedy Recipes available at Mold Mart,  that is the time to utilize your very good idea of attaching a plastic sheeting water barrier to the underside of the crawl space. Make sure the plastic sheeting is 6 mils thick and in one piece [use taping of seams if necessary] to help keep out high humidity and airborne mold spores.

         Q. I recently bought a town home that is contaminated with considerable amounts of mold in the crawlspace beneath the house (photo of one area attached) By visual inspection, I noticed the mold growing throughout the HVAC system, so I have refrained from turning on my heat.  Currently I cannot afford to remediate the home. My question is: Would it be safe to turn on my heat? It is starting to get very cold here in Colorado and I would like to turn it on. Thank you in advance for any information you can provide. [Nov. 15, 2004]
         A. Use duct tape and clear plastic sheeting to seal all supply registers and your inward air duct register to keep mold in the heating/cooling system for mold contaminating your entire home. Do NOT run the heating/cooling system until your entire home and the heating/cooling system have been mold inspected, tested, and remediated. Mold infestation in your heating/cooling system means your entire house is mold polluted. Use portable electric fans as a source of heat for now. Your mold photo illustrates the worst case of mold infestation in a crawl space that I have ever seen. Crawl space mold can easily grow into the insides of the floors and walls above. In addition, airborne mold spores from the crawl space mold can travel in air currents to mold cross contaminate your entire house and to further contaminate your heating/cooling equipment and ducts. Because you are on a budget [like most homeowners], you should consider safe and effective do it yourself mold remediation. Learn how to do mold remediation. Your very first step should be entire home mold testing with either one of our Certified Mold Inspectors or by Use do it yourself mold test kits from a large hardware, home improvement, or safety store. Become your own effective mold expert to improve your personal home or apartment environmental safety and/or the environmental health of your investment properties by reading all five of our mold advice, email delivered books [Mold Health Guide, $15; Mold Legal Guide, $15; Do-It-Best-Yourself Mold Prevention, Inspection, & Remediation, $15; Mold Monsters, $15; and Mold Home Remedy Recipes, $15] for just $49

      Q. My wife has suffered from sinus problems for the past 2 years.  She is 42 years old, had never had much problems before, but has had problems for 2 straight years.  She had sinus surgery and that did not help.  We are wondering if we might have mold or a similar environmental problem.  We live on a crawl space.  It has never had any water.  It is covered with pea gravel and plastic sheeting.  The plastic has some gaps where it goes around peers and along the edge of the walls.  The crawl space is a little musty, but not overpowering.  Our indoor humidity runs about 50 - 60% in the summer time.  No flooding or any visible signs of mold.  No mold smell in the house (I am extremely sensitive to mold from a breathing/congestion and an itchy skin standpoint.  I have not been suffering any problems.  Any thoughts on whether we should consider testing?  Obviously we do not want to spend money chasing wild ideas, but we need to find some relief as well. [June 23, 2003]
       A. Your first step is to mold test the air of the crawl space and of all the rooms above the crawl space, your attic, and the air flow out of your heating/air conditioning ducts/registers. Use do it yourself mold test kits from a large hardware, home improvement, or safety store. What you doing in mold testing the indoor air for is a mold investigation of the possible presence of elevated levels of airborne mold spores which, if present, would be an indication of a possible mold infestation somewhere in your home. A humidity level of 60% is enough to enable mold to start growing. On a year-round basis, you should be maintaining an indoor humidity of 30 to 40% to discourage mold growth. You do this with a programmable dehumidifier that is programmed to keep running until humidity reaches the level you set in the 30 to 40% range.

      Q. I live in a house where the dryer vent is vented through the floor venting directly under the house. It is a frame house with wood floors covered with carpet. Dirt is the foundation. I called a place locally for testing they told me $1500 to test. What are the chances of mold being under my house? I look forward to hearing from you. I am highly allergic to mold and about the beginning of July with Oklahoma's heat, my allergies have gone nuts. Nothing, no medication has helped. [August 28, 2003]
       A. Almost all crawl spaces beneath homes are mold havens because of high humidity from water evaporating from the dirt ground below and from water flowing into the crawl space from outside. By venting the dryer directly into the crawl space, the dryer exhaust creates high humidity levels in the crawl space which makes it very likely you have mold growing on support timbers and the bottom of the floor decking. Crawl space mold easily spreads by growth into the floors and walls above. Crawl space mold also generates airborne mold spores that can enter the house from fresh air intakes of your heating/cooling system and through open windows and doors. You can use our do it yourself mold test kits to test the air of your crawl space, rooms, above, attic, and the outward airflow from heating/cooling duct registers for the possible presence of elevated levels of airborne mold spores, in comparison to an outdoor mold control test. Elevated levels are unhealthy and an indication that your house may have a serious mold infestation problem.

The photographs below are of mold growth in the dirt in a crawl space underneath a regular house [second row, left photo] and beneath an old Arizona trailer home [the other three photographs].