Mold: A home's time bomb

Planning on installing drywall? Better take care of all that hidden mold first
By Tim Carter

NEW YORK (Tribune Media) - Good treatment is often about early discovery. If you've found that dampness-prone parts of your home are covered with mold, better take action right away before a common problem becomes a more serious one.

Visit CNNfn's Home & Auto page each week for Tim Carter's latest question-and-answer column. An award-winning builder, Carter offers tips and answers questions for readers struggling with home improvement projects. His expertise runs the gamut from the installation of decks and fireplaces, to plumbing, roofing and drywall.

DEAR TIM: We recently purchased a seven-year-old home that has a full, unfinished basement. The walls have studs, insulation and a vapor barrier but no drywall yet. We are thinking of installing drywall, but the rear wall has lots of mold growing on the insulation and vapor barrier. What is causing this to happen? How can we stop the growth? How can the mold be removed? Tim and Peggy W., Eagan, Minn.

DEAR TIM and PEGGY: You are lucky you discovered this mold before you installed the drywall. Whenever you see mold growing on a surface inside your home, consider it to be a flashing red light signaling that you could have a serious problem or might have one in your immediate future. A wise person takes immediate action to fix mold problems, because certain molds can cause serious health problems or, in rare instances, death.

Mold is around us 24 hours a day in the form of airborne spores and spores that have settled onto every surface inside a home. These spores are similar to plant seeds. Think of them as time bombs waiting to go off. In almost all instances they already have two of the three ingredients they require to grow and thrive.

The temperature inside most homes, crawl spaces and attics is almost always sufficient to support mold growth. The surfaces that mold spores rest upon are in almost all instances a food and nutritional source. Mold will thrive on drywall paper, wood, certain paints, fabrics, dust, paper, carpet, etc. Soaps and other body-care products that often create a film inside tubs and showers are a smorgasbord for mold. Mold can easily grow inside a cold refrigerator.

The third ingredient that triggers mold-spore time bombs is water. Surfaces that become wet from plumbing leaks, roof leaks, condensation, pet urine or other forms of moisture can sprout mold growth in several days or less. If the surfaces stay wet for extended periods of time, mold can grow at an astounding rate.

Relative humidity levels of 50 percent or greater can supply enough moisture that condensation can start to happen at temperatures close to the actual surface temperature of the object. Water vapor from your basement space probably turned into condensation when it came into contact with the cold insulation and vapor barrier on that rear wall.

Common molds that cause health problems for adults and children often fall into two main categories. Penicillium and Aspergillus are two common indoor molds.

Cladosporium and Alternaria are common outdoor molds that are brought indoors. Innocent pieces of slightly damp firewood can contain vast amounts of mold. Once thrown onto the fire, mold spores can be pumped into the house by indoor air currents that circulate in and around the fireplace.

Seemingly harmless Christmas trees can be loaded with outdoor mold spores. Damp mulch in garden beds can liberate millions of spores, which can enter open windows. Forget about stopping mold spores from getting into your home. It is virtually impossible.

The key to stopping or halting mold is to cut off its supply of water:

• Vent dryers outdoors.
• Install high-quality fans that remove water vapor from baths and kitchens.
• Cover crawl-space dirt with high-performance vapor barriers.
• Fix plumbing and roof leaks immediately.
• Stop water from infiltrating basements and crawl spaces by installing hidden linear French drains around your home. These simple trenches filled with perforated pipe and gravel can intercept and redirect water away from your home.
• Install ridge and soffit ventilation systems. When wind-driven rains cause leaks in brick homes, seal them with breathable, high-performance silane and siloxane water repellents.
• You can stop your mold growth by lowering the relative humidity in your basement or by raising the indoor temperature.

Cleaning mold is fairly simple. A solution of four parts water and one part chlorine bleach can be used to remove mold from tile, concrete, grout and other surfaces that are not harmed by the harsh chlorine.

Fabrics, carpet, painted walls, wood, clothing and other surfaces that are more sensitive can be cleaned using nontoxic oxygen bleach. Oxygen bleach is a powder that is mixed with water. It is readily sold on the Internet and on cable television. Some national club-membership stores carry it as well. It is best to buy it in its pure form. Many companies that sell oxygen bleach add fillers to the product. Find one that is 100 percent pure oxygen bleach.