Even the oil from your skin that is left when you touch an otherwise unsuitable surface, like stainless steel, or the soap residue left from a good cleaning will provide sufficient nutrients to support the growth of some molds. And many of the most common materials found in homes like wood, paper and organic fibers are among the most preferred of mold nutrients. Thus, eliminating mold food from your environment is a virtually impossible task.
Unfortunately, most molds grow very well at the same temperatures that humans prefer. In addition, anyone who has cleaned out their refrigerator quickly realizes that temperatures close to freezing are not cold enough to prevent mold growth and temperatures that are much warmer than humans prefer, like those of the tropics, will grow abundant quantities of mold. Therefore, it is not feasible to control mold growth in our home environment through the control of temperature. Most molds requires the presence of considerable moisture for growth.
The various species of mold have different water activity requirements. In fact, the great majority of serious, large mold outbreaks inside buildings occur where porous, cellulose-type materials have literally been kept wet by liquid water or sustained condensation. Human beings prefer humidities that are below the critical relative humidity for mold growth. Thus, of the four basic requirements for mold growth, moisture availability is by far the easiest mold growth requirement to control in environments that humans like to inhabit.
As you will see from the remainder of this guide, and from the vast majority of the literature on mold control, the consensus regarding effective mold control strategies consists of the combination of reducing the availability of moisture and killing and removing active mold growth colonies.
Growing colonies of mold can also be visually observed in many cases. Although most active mold colonies appear greenish to black typical of mold growing on bathroom tile grout in color, the characteristics of mold colonies growing behind vinyl wall covering in buildings takes on very different characteristics.
These mold outbreaks typically result in pinkish to yellowish staining of the wall covering. They are quite important because they indicate serious, detrimental moisture accumulations within the gypsum wallboard behind the wall covering that can not be removed by your air conditioning or dehumidification systems.
Where these problems appear, they usually require the assistance of a professional equipped with pressure measurement and other diagnostic equipment to determine the source s of the moisture causing the problem. Mold growth on the outside of homes is not covered here and readers are cautioned that these practices may not be applicable in other climates.
The following table of results from experiments that were conducted by the Florida Solar Energy Center illustrate the relative humidity impacts of both thermostat set point temperature and the position of the fan mode switch.
The above wall diagrams from detailed computer simulations that model the combined impacts of heat, moisture and air transport 3 illustrate the importance of this air flow phenomena. The wall on the left bounds a space that is pressurized with respect to the outdoors and the one on the right bounds a space that is depressurized. The 2 Pa Pascal pressure gradient is very, very small — there are , Pa in one atmosphere. Clearly, it is the direction of the pressure gradient rather than its magnitude that is critically important here.
You very much want your home slightly overpressurized in hot, humid climates so that dry, cool indoor air is pushed out of the home through the walls figure on left rather than have hot, humid outdoor air sucked into the home through the walls figure on right.
Fortunately, it is relatively easy to pressurize a home — all that is necessary is that slightly more air be brought into the home than is exhausted. This normally requires a positive mechanical ventilation system. Moisture coming from outdoors can accumulate within the gypsum wallboard that is behind the vinyl wall covering. This normally occurs as a result of house depressurization where outdoor air is being sucked into the home through the very minute air pathways that exist in all normal wall systems.
Where this problem occurs, outbreaks of mold often occur beneath the wall covering on the surface of the gypsum wallboard. Positive pressurization of your home is one method of minimizing the potential occurrence of this problem. If this occurs, outdoor air will be drawn through the small pathways that exist in the exterior building envelope. This, in turn, can result in the rapid and abundant growth of molds — remember, the cellulose paper on gypsum wallboard makes an excellent, preferred mold food.
If room doors are kept open, there will be sufficient return air pathways. Bathrooms: Most bathrooms, particularly tile in and around showers and tubs is regularly wet.
As a result, most bathrooms grow mold and require regular cleaning. A weak solution of water and common household bleach can be used to regularly clean these areas and keep them free of mold.
Low-noise bathroom fans are also recommended to remove excess moisture during periods when it is being generated by bathing or showering. See also exhaust fans. Hazards presented by molds that may produce mycotoxins should be considered the same as other common molds which can grow in your house.
Not all fungi produce mycotoxins and even those that do will not do so under all surface or environmental conditions. Mold growth, which often looks like spots, can be many different colors, and can smell musty.
Color is not an indication of how dangerous a mold may be. Any mold should be removed and the moisture source that helped it grow should be removed. There are very few reports that toxigenic molds found inside homes can cause unique or rare health conditions such as pulmonary hemorrhage or memory loss. These case reports are rare, and a causal link between the presence of the toxigenic mold and these conditions has not been proven. Skip directly to site content Skip directly to page options Skip directly to A-Z link.
Section Navigation. Facebook Twitter LinkedIn Syndicate. Basic Facts about Mold and Dampness. Minus Related Pages. How common is mold in buildings? How do molds get in the indoor environment and how do they grow? How do you know if you have a mold problem? Large mold infestations can usually be seen or smelled. How do molds affect people? Who is most at risk for health problems associated with exposure to mold?
How do you keep mold out of buildings and homes? Inside your home you can control mold growth by: Controlling humidity levels; Promptly fixing leaky roofs, windows, and pipes; Thoroughly cleaning and drying after flooding; Ventilating shower, laundry, and cooking areas.
An air conditioner or dehumidifier will help you keep the level low. Bear in mind that humidity levels change over the course of a day with changes in the moisture in the air and the air temperature, so you will need to check the humidity levels more than once a day. Use an air conditioner or a dehumidifier during humid months. Be sure your home has enough ventilation. Use exhaust fans which vent outside your home in the kitchen and bathroom. Make sure your clothes dryer vents outside your home.
Consider not using carpet in rooms or areas like bathrooms or basements that may have a lot of moisture. How do you get the molds out of buildings, including homes, schools, and places of employment?
Remove or replace carpets and upholstery that have been soaked and cannot be dried promptly. If you choose to use bleach to clean up mold: Never mix bleach with ammonia or other household cleaners. Mixing bleach with ammonia or other cleaning products will produce dangerous, toxic fumes. Open windows and doors to provide fresh air. Wear non-porous gloves and protective eye wear. Small areas such as a shower, or an area the size of a door can often be cleaned by residents, but larger areas might need more professional help.
Another thing mold needs to grow is oxygen. What you need to recognize, however, is that oxygen can fit through even the tiniest of spaces. You want to ensure your home is completely sealed from the outside. This means having high-quality insulation that keeps all air from getting into your walls where mold can grow unseen. Mold can feed on a number of things, including meat and vegetables, drywall, material and wood. There are a couple of things you can do to avoid feeding the mold in your home.
First of all, maintaining a clean home free of food waste will prevent mold from growing on your kitchen counter, under your couch and in your refrigerator.
Limit eating to only areas of the home with hard flooring and clean them daily. But that would be expensive and impossible to maintain. Instead, use this as a warning to pay special attention to areas that are dark in your home. Those are the ones that need to be kept dry and free from mold food sources more than areas that get natural sunlight.
The last thing mold needs for an ideal environment is warmth. Mold grows fastest in temperatures above 60 degrees Fahrenheit. Since your home should always be above 60 degrees, it means that mold can grow inside year-round.
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