WHY DO ATTICS MOLD?
Attic mold is a winter issue – When an attic stays warm, or has visible icing, no snow is showing on the roof and your neighbors have snow on their
roof; This isn’t necessarily an insulation issue. It could be the result of a venting and humidity issue. Check to see if your home’s furnace humidifier is set too high. A rule of thumb, if you’re noticing moisture on the inside of the windows throughout the home (not just the kitchen or bathroom) then you are adding too much moisture into the air. Each person in a household produces 75 gallons of water per day thru breathing, perspiring, cooking and bathing. Pets also add to the humidity of the home, especially fish tanks.
All the moisture travels to the relatively cold attic and condenses on the attic roof decking. Attics in Northern Ohio have areas that stay colder than other parts. It’s common for the north side of the attic to have more mold damage then the rest of the attic. This happens because the north side receives less direct sun on the exterior of the roof. Attics with bath venting directed into the attic may have dark mold staining near the bath fan discharge.
WHAT TYPES OF MOLD ARE FOUND IN ATTICS?
Molds commonly found in attics are usually less toxic than those found in the basement. Keep in mind not all molds that are black produce toxins and some molds that are white and other colors can produce toxins. We only bring this up because most people assume mold is always dark and black. Dark mold found in most attics is not toxic (although it may be allergenic). The most common type is Cladosporium mold which can cause common health conditions
like “Jock Itch” and “Athlete’s Foot”. This is a normal mold you would expect to find in attics. Attics are unique areas because they contain a hybrid of both commonly found inside and outside when they are ventilated properly. This happens because they are under cover of a roof but air can travel freely and be blown in and blown out. Cladosporium mold is one of nature’s strongest recycling tools and is responsible for the decay of organic materials similar to turning leafs and wood into topsoil. When the dangerous types of mold are found in attics they will be accompanied with a higher humidity level.
Issues causing attic mold can include an on-going roof leak or severe lack of ventilation. Aspergillus which is commonly viewed as a white, powdery, fuzzy material and Stachybotrys “the black mold” can often be found in attics that have suffered a long period of water intrusion like a roof or chimney leak.
HOW TO CORRECT ATTIC MOLD
A properly vented attic never molds. Once an attic becomes molded you have to correct the venting issue first in order to ensure it doesn’t come back. Is it necessary to have proper venting per square foot of the attic floor? Most sources say 1 box vent per 400-500 square feet of attic floor. A typical 1000 square foot attic would require 4 to 5 box vents. The next
consideration is to ensure that bathroom fans are properly venting out of the attic. This is a common venting issue that leads to mold growth in the attic. It’s important they are vented through the roof for the roof to breath. Without proper venting, the attic will build up with heat in the summer causing the roof to expand, pop roofing nails, and loosen shingles. This reduces the life of a roof and will lead to leaking and degradation of the roofs integrity. If you ever noticed in the summer months that your second floor is drastically hotter than the downstairs it’s likely the roof is not vented correctly.
In the winter the attic sheathing gets wet and softens causing the wood decking to bow and decay. Indications of this problem include: icicles and ice damming. If you’re wondering why your roof doesn’t have snow on it when your neighbors does; this is likely caused by improper air flow not a lack of insulation. Ridge vents alone won’t do the job. This is especially true for hip roofs (pyramid/ pie shaped roof lines) if the peak vent or ridge vent is too small or there is not enough running feet installed from the entire length of the roof. Other roof issues occur when a roof has a very low /
easy to walk pitch. These roofs have air that doesn’t really move; warm air sits in the middle of the attic and doesn’t get out through the ridge vent. Ridge vents work best on homes that have a long run on the peak and are more steep. This allows the ridge vent to act as a chimney, but the ridge is only one part of the system. The ridge is an outlet of hot air. Proper installation of this venting system would include soffit venting. This lower vent at the eves allows cooler air to come into the attic and pushes hot air out of the attic through the peak. Some houses have soffits but they are sometimes decorative and are not open enough to allow for proper venting . These can be opened and we can discuss this as an option however in most cases the biggest value is to add additional box vents (sometimes called static vents or turtle vents). Generally if you can’t see daylight in a watertight roof then there is not adequate ventilation. Bathroom fans need to vent directly out of attic. Venting into the attic adds unwanted moisture. This can even happen when the
bathroom fan isn’t being used. The warm moist air for the home’s interior is still being pushed through the bathroom fan opening. This occurs when the forced air furnace kicks on and pushes air that has more force behind it then the air in the attic