Risks from Mold in Homes and Buildings

Although people don't spend much time thinking about mold until they discover its presence and have to clean it up, or hire professionals to remove the mold and remediate their property, mold is all around us. For the most part, mold is not considered to be harmful or dangerous, and it acts much more as an irritant than a health hazard.

The Dangers of Mold

You have heard about "black mold" and "toxic mold", but those labels are more scary than the reality. The fact is, most mold appears to be black in color, and "toxic mold" is largely a misnomer.

Although some molds produce toxins, the amount of mold exposure you are likely to encounter in a typical building is not going to result in a health hazard.

Even when toxicity is not an issue, airborne mold spores can trigger allergic reactions, cause eye irritation, respiratory problems, or infection. People with mold allergies may nonetheless find living in a moldy home to be uninhabitable, and people with compromised immune systems should minimize their exposure to mold.

If you believe you are having negative health consequences due to exposure to mold, you should consult your doctor about your symptoms. You should also consider having the air quality of your home checked for mold, as well as for other possible irritants.

For example, chronic headaches at home that you initially believe to be caused by mold may turn out to be the product of a gas leak or carbon monoxide build-up. You may have symptoms from exposure to other common irritants such as pesticides, cleaning solutions and solvents.

Liability for the Presence of Mold

Homeowners and other property owners may face liability if they fail to disclose the presence of mold in home or building when selling to an unsuspecting buyer.

For example, should a seller paint over a wall that shows signs of mold, the seller might be sued when the buyer later discovers a long-standing slow leak within the wall space that has resulted in an extensive mold problem.

Home Designers and Builders

Home designers and builders, as well as the manufacturers of construction materials, may face liability if they are negligent in the design or construction of a home, or if construction materials don't perform as promised or expected, resulting in the intrusion of water into roof and wall spaces and the development of mold.


Landlords may face liability to tenants, with a small number of states and communities having passed laws and ordinances requiring disclosure of mold or other problems that may affect air quality within a rental unit.

Landlords have a duty to maintain their premises in a habitable condition, and thus should promptly repair water leaks and remediate mold problems that affect their rental properties. However, where a tenant causes mold to occur due to poor hygiene and inadequate cleaning, the landlord is not responsible for any health consequences that result, and may be able to charge the tenant for damage caused by an unreported water leak or mold build-up.

Health Care Facilities

Hospitals and facilities that care for people with compromised immune systems must take appropriate measures to control for dust and mold exposure, lest their patients develop fungal infections.

Damages for Mold Problems

Mold claims involving real estate usually focus on the cost of remediation, removing all of the mold, sanitizing the affected areas, and repairing the underlying structure. Where air quality issues are involved, claims may also be made for personal injury, for medical costs and pain and suffering resulting from mold exposure.

A home buyer or tenant may also make a claim for emotional distress, possibly even where evidence of other injuries is scant. Particularly where mold tests reveal the presence of a toxic mold, the occupants of a building may suffer considerable fear and anxiety as a result of their exposure even if they don't actually suffer illness as a result of mold exposure.

Preventing Mold

If you are a property owner, the last thing you want to learn is that your property has become home to a mold colony. Although mold can result from defects in the design and construction of a home, from mistakes made during repairs, and from neglect of home maintenance, most property owners can avoid the development of mold.

If a buyer is interested in a property with mold issues, the buyer will typically demand remediation as a condition of proceeding with the purchase.

What leads to mold? The chronic presence of moisture.

  • Keep the exterior of the structure in good condition, making sure that the roof and siding are properly maintained, and that gaps are properly sealed.

  • Attics should have appropriate venting to prevent condensation from building up.

  • Attics should be properly insulated, and care should be taken not to allow warm air from the main building to leak into the cold attic space where moisture will condense.

  • Watch for the formation of ice dams in the winter, as the ice can force its way under a shingle and allow water to enter the building.

  • Water may become present due to leaks in plumbing, both in pipes and drains.

  • Make sure that all of the vents in the building, including kitchen, bathroom and dryer vents, properly carry air to the outside of the building.

If you suspect that you may have a plumbing leak, have it repaired. You may be surprised how much damage even a small leak can cause over time, not only through the possibility of mold but also by causing wood to expand and rot.

If you find mold in a building that you own, you need to determine how water is getting into the affected area and cut off that water supply.

Depending upon the extent of the mold problem and water damage, you may need to hire professionals to remove the mold and repair the damage.

If you do not take these steps the damage will get worse and, in the future, prospective buyers will be deterred by the unresolved mold problem.

Copyright © 2014 Aaron Larson, All rights reserved. No portion of this article may be reproduced without the express written permission of the copyright holder. If you use a quotation, excerpt or paraphrase of this article, except as otherwise authorized in writing by the author of the article you must cite this article as a source for your work and include a link back to the original article from any online materials that incorporate or are derived from the content of this article.

This article was last reviewed or amended on May 8, 2018.