Prevent Mold: Control Growth Factors

The nutrients required in order to make mold spores germinate are readily found in dust, dirt, and complex organics such as wood, adhesives, paper, paint and building textiles. The reproduction of fungal spores is assisted by many factors, such as moisture, relative humidity, material pH, moisture pH, available nutrients, the velocity of air, air temperature, material temperature, substrate composition, and the number and type of preexisting spores. The severity of mold growth depends on the length of time that materials are allowed to remain damp or wet. That's why early detection is critical.

Let's face it. All houses and commercial buildings contain millions of dormant mold spores. Every time we open a window or door, mold spores are blown in. Every person that enters the home brings mold spores in from outside. Pets returning from outdoors help populate our homes with mold spores. Construction materials, such as drywall, wood framing materials, and trusses are loaded with mold spores when they are delivered to job sites, even before the home is built. The mold spores are not the problem, water damage is the problem. Just like a seed that sits in a package waiting to be planted, mold needs moisture to germinate and grow. Mold will not grow unless the dormant mold spore gets wet.

The industry term that describes moisture content is EMC (equilibrium moisture content). EMC measures the moisture in building materials in comparison with the humidity of its environment. These building materials (substrate materials) include wood, natural stone, masonry surface, ceramic tiles, porcelain tiles, and drywall. When building materials are soaking wet, an obvious opportunity for mold germination and growth exists. Yet, there is a great opportunity for mold growth even when materials are damp. Even in non-flooded environments, mold can grow when the humidity reaches 75% and materials are allowed to reach EMC of 75% or greater. In wood, the EMC figure is much lower. The recommended safety margin for saturation of wood to prevent wood decay is 20% EMC.

Control moisture and you also control termites. Many times, when QCI MOLD TAMPA remediates long-term mold growth in wood structures, we also find termites because termites enjoy the same moist wood diet as does mold. The same moisture factors that encourage mold growth also provide the environment that encourages termites.

Composition of building materials. Mold is a vital requirement in the outdoor environment. Mold helps break down organic materials such as dead trees and leaves, creating nutrients that make our soil rich and able to grow food. In the indoor environment, mold feeds on the same types of nutrients as in the outdoor environment. Therefore, wood products, paper products (paper on drywall), dust, wall paper, and wallpaper glues are all prime food sources for mold activity.

When designing and building structures for human habitation, due care should be exercised when choosing building materials. Exterior walls of houses and commercial buildings are susceptible to moisture penetration. Therefore, wallpaper should not be installed on exterior walls. Bathrooms and kitchens, areas that have higher than normal relative humidity levels in relation to other rooms throughout a structure, should not be wallpapered. The choice of wood over metal studs for your wall framing can be a function of price, durability and engineering requirements, but the use of wood as a framing material in a wall cavity will provide food source material for mold.

Water source contamination levels are critical in assessing mold growth. Is the water intrusion from a clean source or a contaminated source? Typically, pipe leaks, window leaks, and roofs leaks are considered clean water intrusions. Mold grows at a more controlled rate in clean water intrusions than in black water intrusions. Flood waters from rising creeks, lakes, street sewer systems and sewage backups are considered Category 3 black water intrusions. Black water intrusions require more stringent, timely, and aggressive remediation standards. Mold grows at a much more aggressive rate from water damage from a Category 3 black water source.

Relative humidity also affects mold growth on building surfaces. Humidity is simply vaporized water in the air. The term most often used to define the amount of water vapor in the air is "relative humidity." Relative humidity is the percentage of water vapor in the air at a specific temperature, compared to the amount of water vapor the air is capable of holding at that temperature. Warm air holds more water vapor than cold air. When air at a certain temperature contains all the water vapor it can hold at that temperature, its relative humidity is 100 percent. If it contains only half the water vapor it is capable of holding at that temperature, the relative humidity is 50 percent. High humidity levels will promote surface mold growth. Temperature affects the relative humidity. If you are experiencing small mold spots on furniture, walls, mirrors, there is a problem and you should consult a licensed indoor air quality professional.

Air velocity promotes water evaporation from indoor material surfaces. That is why we usually see accelerated growth rates for mold when the HVAC system is inactive or inoperable. Additionally, in high humidity, indoor environments, stagnant areas seem the most susceptible to surface mold, such as closets and inside of cabinets because of limited air movement.

Mold spores are mesophilic organisms, meaning they like moderate temperatures. Edible mushrooms are grown in temperature conditions varying from 68-86 degrees F. Unwanted indoor mold thrives in the same temperatures. In order to deter mold growth, conventional wisdom recommends keeping the air conditioning on a lower setting.

Time is of the essence. The longer the mold's food source or building material remains wet, the more mold will grow. The variety of mold that grows in an indoor environment is directly related to the length of time the building materials remain wet. Stachybotrys (the famous black mold) can only grow after building materials are wet for an extended time, usually in excess of 7-10 days.

Mold is a condition that is often associated with sick buildings, and as with any illness, early detection is the key to recovery. Contact QCI MOLD TAMPA, an industry leader in Florida moisture detection, mold testing, water damage mitigation, and mold remediation to preserve the health of your building.