Q: I live in Daytona Beach during the winter. We own a double-wide mobile home that reeks of a musty mildewy odor. We keep our home very, very clean. We are located about 60 feet from a lake. The crawlspace has been checked and there are no signs of mold or water leaks. We keep the windows open most of the time and the ceiling fans on. The house was repainted two years ago.
During the summer, we keep the air set at 85 and the ceiling fans on. When you enter the home, you can smell the odor about 5 feet away from the door. The floors are carpeted and ceramic. All flooring is about 5 years old. There are no signs of water leakage. When we arrived last year, there was mold growing everywhere. This year there was a little mold on a living room table and on the side of some coasters.
How can I eliminate these odors once and for all? I don’t want to mask them, I want to find the source of the problem and eliminate it.
A: A mobile home has what is called an underbelly, which is a plastic wrap that covers all the floor joists, ductwork and plumbing under the home. In most states the ground under the home will also have a ground cover vapor barrier. Whatever the odor is, it is trapped between the two vapor barriers.
The musty odor in your home is most likely coming from the loose fill fiberglass insulation used to stuff the underbelly of the home. Some say it smells musty, while others say it reminds them of urine odors, but whichever offensive odor it is, it may be sealed in the floor system. When you open the windows and reduce the air pressure inside the home, the air and odors trapped in the underbelly escape to the home to equalize the lost pressure.
In warmer climates you can remove the underbelly and the insulation, but the ductwork will need to be insulated to prevent condensation by using a fiberglass-free duct wrap available at most home stores. In mild climates, once the insulation has been removed, the foundation walls and the ends of the floor system need to be insulated with rigid foam boards or with a more expensive spray-on expanding open cell foam.
In colder climates the insulation should be removed and the floor system, ductwork and plumbing can be encased in closed-cell spray foam to protect against freezing weather. In all cases the ground should be covered with a sealed 6-mil or heavier black plastic vapor barrier to prevent the moisture in the soils from condensation and reaching the floor system above.
Setting out several open containers of household bleach to evaporate and absorb the odors can mask the odors that are now present. Small, recyclable plastic containers can be used and then thrown away once the bleach crystallizes. The bleach should never be in an area accessible to children or pets.
C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Send home improvement questions to C. Dwight Barnett, Evansville Courier & Press, P.O. Box 268, Evansville, Ind. 47702 or e-mail him at d.Barnett@insightbb.com.