Must, mold, moisture and basement refurbishing

Farm Forum

BROOKINGS – The recent moisture and increase in temperature provide ideal conditions for mildew and mold growth in homes lower living areas and basements, says Marjorie Zastrow, SDSU Extension Nutrition Field Specialist.

“For those dealing with the dismantling of a basement due to flooding, taking time to clean and prepare for repairs can be time consuming and frustrating,” Zastrow said. “It is important to take precautions to prevent the growth of mold in our living environment for our health as well as to maintain the value of property.”

Zastrow says the growth of mold can have significant health effects on individuals of all ages, particularly those who are very young, the elderly and those with a compromised immune system. It too can impact the value of the structure.

Controlling moisture is one of the primary defenses in preventing mildew and mold growth, says Zastrow.

“Even though you may not have water issues to deal with, just the presence of high humidity can support mold growth,” she said. “Molds can be detected by appearance and/or a discoloration of surfaces.”

If you have mold issues, Zastrow says your resources are best spent taking care of the problem rather than go through the costly process of identifying the particular strain of mold.

In the lower living areas and the basement it is recommended that that humidity be kept at 60 percent or lower to alleviate the growth of mold.

“Even if you did not have water this spring, if your humidity is 60 percent or greater, you have the potential for mold growth,” she said.

To alleviate the potential for mold growth, Zastrow says to begin by thoroughly cleaning the area using a general purpose household cleaner. This will remove the dirt and grime which mold spores feed on. Secondly, you can sanitize the area with a rinse of 1/4 to 1/2 cup bleach per gallon of water.

“Remember, bleach is not a cleaning agent and cleaning is a critical step,” she said. “If you choose to sanitize, the solution should remain on the affected area for 10 – 15 minutes.”

She reminds homeowners to never mix bleach with another cleaning agent.

After cleaning, one of the most important steps in controlling mold growth is dehumidification.

“Without the presence of moisture, mold spores will remain dormant,” she said. “When adequate moisture is present and there is a source of food they grow.”

It is recommended that the moisture level be from 40-60 percent. The dehumidifier is the most efficient means to reduce and control moisture. When operating a dehumidifier be sure that your dehumidifier is sized to your square footage; some larger homes may need two or more.

If operating a dehumidifier, be cautious in opening windows as the moisture is likely higher outside than inside.

Reducing clutter is an important step in controlling the growth of mildew as well.

“Piles of cardboard boxes, boxes of clothing, clutter and just too much stuff will absorb and hold moisture, as well as inhibit the air circulation pattern,” Zastrow said. “These items make it hard to clean, as well as keeping the area ventilated.”

Refurbishing damaged walls

If you had persistent seeping or standing water in your basement you may have had to remove flooring and/or wall boards. If wall boards were removed it is recommended that they be cut 12-inches above the saturation line.

For these situations, Zastrow says it may take several weeks or months to dry out before re-finishing is recommended.

“The amount of time it takes to dry is very much dependent on the type of construction materials you have, the amount of moisture/water you had, as well as the amount of time the water/moisture was present,” she said.

Those homes that had significant damage, i.e. for those that removed wall board Zastrow says it is recommended that drywall, paneling or other coverings not be replaced until the moisture content of the studs is 12 percent to 16 percent or less. The moisture content of wood can be checked by using a Moisture Meter often available from a contractor. Moisture content may vary from one location to another, so readings should be taken at several locations.

“The meters can provide a range of moisture in sheetrock; if the dehumidification process has begun, a more accurate moisture reading should be taken behind the sheetrock as the face of it may appear dry, while moisture is harbored behind,” she said.

Refurbishing Flooring

Before you replace a floor covering on a concrete floor, determine if the concrete has dried out enough. To get an idea of the moisture content of cement several sources recommended a simple home test by taping down a 2 x 2 foot sheet of heavy gauge polyethylene plastic in an area not in direct sunlight, and laying a heavy blanket over the top for a period of a day or two.

If condensation forms on the underside of the polyethylene the floor is too damp for laying vinyl or carpet with rubber underlay or backing. If the floor is too damp, remove the plastic and continue the dehumidification process. After the floor has allowed to dry, repeat this test; when the surface under the plastic is dry for a period of 2 to 3 days you may consider renovation at that time. It may take weeks or months for the concrete to dry.

When refurbishing, it is wise to consider the electrical work in the walls and take necessary precautions to avoid further damage to the home and the person working on it. For jobs beyond one’s competency, contact a licensed professional.

What is Efflorescence and how to deal with it

If you have a concrete floor in your basement Zastrow says you may have some very noticeable “white growth” which looks like mold.

If your floor is clean and it is only noticeable on the concrete it is likely efflorescence. Efflorescence is a reaction of moisture with the compounds in your cement.

“If it is efflorescence, when you touch it, it will crumble; you sweep it and it turns to a fine powder and it appears generally where there are cracks in your concrete,” Zastrow said.

The availability of water, permeability of the concrete and amounts of soluble compounds determine how much efflorescence will occur and when it will stop. The water temperature and hardness also have an effect. A significant amount of efflorescence can cause damage to your concrete over a period of time, but generally she says it is not a health hazard.

Efflorescence can be removed by rinsing with water alone if it has just appeared. If the efflorescence reappears it can be removed with one part Muriatic Acid (hydrochloric acid) to 9 to 19 parts water and sponge the affected areas. Following the application of the Muriatic Acid dilution, the area should be rinsed with water.

“Generally this process can be done with a sponge. Dehumidification also will help to dry the concrete and control the growth of the Efflorescence,” she said.

Extreme caution should be taken when working with Muriatic Acid. When working with Muriatic Acid wear rubber gloves, appropriate shoes/neoprene boots, have the area well ventilated, and be sure there are not any other chemical compounds present. Those with compromised immune systems or the elderly should not work with Muriatic Acid. A publication entitled Efflorescence -Minimizing unsightly staining ( by Bruce A. Suprenant will provide further information regarding Efflorescence.

For more information on flooding clean up and renovation and contact the SDSU Extension AnswerLine at 1-888-393-6336 from 9 a.m. to 4 p.m. CST or visit