NJ Homeowner's Guide to Attic Mold

According to information published by the Environmental Protection Agency (EPA), half of the structures in the United States contain mold. Mold often spreads in attics because attics contain many of the key elements necessary for mold growth. Additionally, attics are often areas of the home where people do not spend a great deal of time, therefore, mold can spread over large areas before it is recognized. 

What is mold?

Mold is a fungus. Due to fungi’s unique characteristics, they can neither be classified as a plant nor an animal. Because of that fact they were given their own kingdom for scientific classification in 1969. 

Mold is incredibly plentiful throughout the world. It is found both indoors and outdoors and on every continent including Antarctica. The estimates for the number of species of molds range from tens of thousands to over three hundred thousand. Some molds are benign, however, some have been deemed toxic to people. Although there many species, all species have a number of common characteristics. All molds have a defined cell wall, reproduce via spores, and lack chlorophyll (a substance found in all plants). 

How does mold grow? 

The majority of molds feed on decaying organic matter. When mold is found outdoors the mold’s ability to consume decaying matter makes it a valuable part of the ecosystem. However, when mold is found indoors, the fact that it helps break down organic matter (like wood), creates a serious problem. 

In order for mold to grow there are three crucial elements. The first necessary element is the presence of mold spores. Mold spores are extremely common both inside and outside of homes. With the average mold spore being 40 microns (about one third the width of a human hair) or less in size and, therefore, invisible to the naked eye, there could be a large number of mold spores in an attic without a homeowner ever knowing they are there. 

Another crucial element for the growth of mold is moisture and humidity. Due to both condensation and roof leaks, attics are commonly more moist and humid than other areas of the home. Once the humidity level in the attic is above 60% the chance of mold growth increases significantly. 

Lastly, in order for mold to grow it must have a food source. Since mold eats organic materials (anything that contains carbon atoms) it can only grow in areas that have organic material. A number of organic materials are found in the average attic including building materials, like wood. Many people also use their attics for storage so there will be additional organic material like paper and cotton.

Why is mold often found in attics?

The most common reason mold is found in an attic is because of excess moisture. The three main reasons for moisture are condensation, leaks, and improper ventilation. Condensation is a very common problem in attics because attics are usually the barrier between the outside elements and a home’s temperature controlled living area. When warm air from the living space of the home reaches the cold air on the attic walls and roof, condensation can form. 

Another major contributor to mold in attics is leaky roofs. Unlike other areas of the home that are used on a regular basis, a leak that drips into an attic may go unnoticed for a long period of time. Roof leaks are common but they are often not noticed until the leak is great enough that it causes a problem with the top floor’s ceiling. By that point, the mold growth in the attic could be extensive.

Improper ventilation, like condensation and leaks, can create a climate that encourages mold growth. When moist air is allowed to stay in the attic, or even worse when the attic is ventilated, mold has a much greater chance of spreading. When some homes were constructed they used the attic as the area in which to vent air from other parts of the home. Moist air from bathrooms, kitchen ranges and dryers were all vented to the attic. This is a very bad practice (so bad that it is against building codes in a number of municipalities). Sending moist air to the attic will encourage mold growth. This is a significant problem because mold can begin to colonize in twenty-four hours after the spores find the right growing conditions. Mold is likely to continue to grow rapidly until something is done to change the climate in the area where it is growing. 

What are signs of attic mold?

There are three places you should look for signs of mold growth in your attic. They are on your roof, on the ceiling in your upper level living space, and in the attic itself. When you are outside you should make a visual inspection of your roof and the area around it. Check for roofing shingles that may have been pulled off in heavy wind. Take special care to look for worn or warped shingles at the roof’s edge. Just below the roof line, look for warped or rotted eaves and fascia board. In the winter, look to see if there are ice dams in the gutters and in the warmer months check for leaves or other debris that can cause gutter issues. Any of these issues are signs of possible leaks.

When you are in your home, inspect the ceiling for signs of damage. These signs include ceiling paint that looks darker in some areas as well as ceiling plaster that is bubbling or expanding. Unfortunately, if the signs of the leak are noticeable within the living space the chance of a serious mold issue in the attic is very likely. 

The most important place to inspect is the attic itself. Check the insulation in the attic for signs of moisture. Pay special attention to the insulation closest to the eaves. Look for warped or rotting wood anywhere in the attic. Check for possible leaks from the roof and make sure to inspect the area closest to the chimney (flashing is often installed improperly which leads to leaks). Of course, if you see actual mold, you know you have an issue with not just mold but also moisture.

What is the best way to remedy attic mold?

Since there are a variety of ways moisture can get into an attic, it is advised that a reliable mold expert should inspect the attic if there are any concerns about mold. A mold professional will be able to inspect the attic and find the source of the mold as well as remove the mold that is currently in the attic. It is very important to work with a professional that does a complete inspection of the attic because even if the mold is removed, if the source of the moisture is not addressed the likelihood of the mold returning is significant.