attic mold

Mold in Attics

It is becoming common to discover mold in the attics of homes. Newer homes are built with lumber that is more porous and more susceptible to moisture penetration than older homes. New homes are also sealed up tighter for greater heating and cooling efficiency, leading to a buildup of moisture. In addition, home inspectors, other contractors, and even homeowners are more aware of mold issues. Whatever the situation, the likelihood that you will need to deal with mold in an attic is higher than ever.

Causes of Attic Mold

Mold requires three things to grow; oxygen, water, and a source of food. Since oxygen and food sources for mold are plentiful, it is easiest to limit mold growth by limiting the amount of available water. Below are some common ways water accumulates in attics, often leading to mold growth.

Inadequate Ventilation

Attics need proper ventilation to allow moisture to escape. This can be done using powered exhaust fans or through vents in the roof as hot air rises and escapes. Usually, there are also soffit vents that allow air to enter the attic under the eaves.

If these components are missing or not functioning, warm air and moisture can become trapped. This causes water to condense out of the air against cold surfaces such as air ducts and cold roofs.

Insufficient Insulation

Attic insulation compresses over time, making it less effective. There also may not be enough insulation in the attic, or the insulation has been moved around, creating insufficient coverage.

Whatever the cause, too much warm air escaping into the attic can cause moisture condensation issues. This is commonly the cause of mold growth that is primarily on the north side of the roof, as that is the side with no direct sunlight and is often cooler than the rest of the roof, resulting in condensation of water on the surface. The fix is usually as simple as adding more insulation.

For extra protection, you may want to add a vapor barrier between the ceiling and the attic joists. This can be expensive to do unless it is done during construction before the ceiling drywall is installed.

Excessive Moisture Intrusion

Even with proper ventilation and insulation, excessive moisture can cause mold growth. Because warm air in the home rises, moisture problems in the attic usually come from moisture inside the home or crawl space. There are many possible moisture sources in the home, but faulty humidifiers and pipe leaks are some of the more common.

Bathroom Exhaust Fans

Exhaust fans in bathrooms are intended to evacuate hot, steamy air out of the bathroom and vent it to the outdoors. If the vent is improperly installed, or if the duct becomes damaged, it may expel that air and moisture into the attic. This usually results in mold growth near the vent, but if left unchecked it can spread to the rest of the attic.

Water Leaks

Roof leaks, pipe breaks, and other direct sources of water intrusion can lead to mold growth in the affected area. Without correction, this can lead to a buildup of moisture in the air, allowing the mold to spread to the rest of the attic.

A Resale Issue, Not a Health Issue

It is possible for mold in the attic to cause potential health issues if something is drawing air down into the home, but that scenario is uncommon. Air in the home usually moves up as warm air rises, and exits through vents, making it more difficult for the mold spores to contaminate the home.

It is much more likely for attic mold to become an issue when you try to sell the home. Most buyers will be hesitant to buy a home with mold in the attic, and most home inspectors will recommend correction of visible mold growth. In our experience, the sale process goes more smoothly if you correct these issues before listing the home.


Treating the Mold

Many companies will clean the area and seal the staining with paint. We prefer to remove the majority of the staining using a treatment that we developed. This treatment is a quick and cost effective way of dealing with the issue, and protects resale value. Often, it leaves the wood looking like brand new. See the video below for an example of our work!



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