Remove source of moisture to keep mold from reappearing

Q: We are fixing up our house to sell. There are a couple of small moldy spots on the ceiling and walls from previous leaks. They look bad, but they have caused no problems. How can we fix them ourselves? — Kyle W.

A: Homeowners have major concerns today about mold in houses because of the many studies done on dangerous black mold. Actually, most mold looks pretty black on a light surface, so people — especially those with children — are understandably concerned when they see any discoloration from mold.

Unless you live in the desert with extremely low humidity, a house will have mold growing somewhere in it. Even in relatively dry climates, just the normal human activities in a house create enough moisture to allow some mold to thrive. This is most common in kitchens, bathrooms and laundry rooms.

If the potential buyers have a qualified house inspector check your house before they sign the contract, the mold will likely be detected, so it is wise to repair the spots now. Since they are small moldy spots, you are allowed to fix them yourself. The EPA has recommended guidelines for mold abatement, and the size of the moldy area is a factor.

It helps to understand how mold thrives. Mold spores can be thought of as mold seeds. The are in the air, on your shoes, and almost everywhere. They can remain dormant for a very long time and become active when they come in contact with moisture and an organic material.

Soap, dead skin cells, oils, food particles, etc. will support mold growth. The amount of these organic materials can be so minute that you cannot even see them and surfaces appear to be clean. Some molds can appear and darken a surface within just a few days.

Since you just have a couple of relatively small areas of mold, there likely were, or still are, leaks or other sources of moisture there. Removing the source of the moisture is imperative to keep the mold from reappearing. The ceiling leaks will be much easier to find than the ones in the walls.

Once you have found the sources of the moisture and eliminated them, inspect the moldy areas to determine the extent of the damage and its depth. Although it may not be a dangerous type of mold, it would be wise to wear gloves and an approved

N95 breathing mask. This is the same type of mask recommended when there is an outbreak of bird flu.

Cover the floor with a plastic sheet. Cleaners for mold are available at home center stores, but a solution of 25% chlorine bleach in water is also effective.

Scrub a large area of the surface around the spots to try to remove and kill the mold. The moisture probably came from behind the wall and ceiling, so the mold is likely deeper than just on the surface.

It is best to remove and replace the section of drywall. This also allows you to inspect the lumber and insulation behind it. Cut out a piece slightly larger than the moldy spot on the surface. For the easiest repair, make your cut in the drywall from the centerline of one stud or joist to the next one. When you install the new piece of drywall, it will be supported on each side.