Mold in the Home: What Homebuyers Need to Know

by Alayna Schroeder

Recognize potential mold problems before buying a house — and get the seller’s full disclosure for mold problems you can’t see.

No one wants to buy a house with a mold problem. Unfortunately, mold problems are not always easy to detect. If you are looking to buy a home, learn how to detect mold in homes, get the seller to disclose mold issues, and remove mold if you decide to buy a home damaged by it.

Mold in the Home

Mold is a fungus that comes in various colors (black, white, green, or gray) and shapes. While some molds are visible and even odorous, mold can also grow between walls, under floors and ceilings, or in less accessible spots, such as basements and attics. Mold does best in water-soaked materials (paneling, wallboard, carpet, paint, ceiling tiles, and the like) but can survive in almost any damp location. Mold can grow in houses situated in the desert, and it can grow in homes in hot and humid climes.

Here are some common places in a home where mold is likely to take hold:

  • around leaking pipes, windows, or roofs (the constant supply of water gives mold spores the start they need)
  • any place that’s been flooded and hasn’t been thoroughly dried
  • tightly sealed buildings (common with new construction), which trap excess moisture inside, and
  • in homes with poor ventilation, numerous over-watered houseplants, and housekeeping habits that ignore obvious dampness and don’t include airing the place out.

Besides presenting an ugly appearance and, sometimes, an unpleasant odor, mold can cause health problems. In the worst cases, a few types of molds produce mycotoxins, which can cause rashes, seizures, unusual bleeding, respiratory problems, and severe fatigue in some people. Fortunately, most molds are of the non-toxic variety.

How to Detect Mold

You won’t always know if there is mold in a house you’re considering buying, but you can take a few easy steps to try and find out.

Be on the lookout for mold. When you’re thinking about buying a home, look for the elements above to figure out if there are any obvious signs of mold or the potential for mold. Keep your eyes peeled for standing water in the basement, water marks on walls (particularly recent-looking stains), or musty smells (particularly in bathrooms, kitchens, laundry rooms, basements, cabinets with plumbing, or other areas with plumbing).

If you’re looking at a newer home, find out whether it is built with “synthetic stucco,” also called the Exterior Insulation and Finish System (EIFS). This airtight barrier is supposed to improve insulation, but if improperly installed, may allow water penetration and mold growth on the inside of walls.

Ask your home inspector. If you have the home professionally inspected before you buy it, your home inspector may see obvious signs of mold or water damage. While it’s not the inspector’s job to look for mold, most home inspectors will mention obvious signs of water damage and the possible presence of mold. And because the inspector will poke around in spaces you might not, he or she may see things you wouldn’t.

Don’t hesitate to ask whether the inspector saw signs of mold or potential mold dangers, and ask that these results be included in the inspection report. Some inspectors may be wary of this, because they want to avoid liability for any mold-related problems. But all should be comfortable talking to you about whether they saw anything suspicious.

Ask the seller to disclose any mold or water-related problems.  Some states require sellers to disclose information about mold (see “Required Seller Disclosures,” below). But that isn’t true everywhere. Even in states where mold disclosure is not required, you can still ask for such disclosure. In addition, ask questions about things that could lead to mold growth, such as “Have any pipes ever burst?” or “Have any of the windows ever leaked?”

Listen to agents and appraisers. In some states, real estate agents or brokers have a duty to disclose problems they know about. Likewise, an appraiser should notify you if he or she sees an obvious sign of a mold problem if it could affect the value of the property.

Required Seller Disclosures

Several states require sellers to reveal particular facts within their knowledge when they sell their homes. In some states, sellers must make disclosures about mold growth specifically. A quick visit to your state’s department of real estate should let you know what your state requires.  Again, even if your state doesn’t require the seller to make this disclosure, don’t hesitate to ask for it.

Keep in mind that the seller’s duty to disclose only relates to things the seller knows about or reasonably should know about — he or she doesn’t have a duty to go poking around in the walls to see if there’s mold, for example. That’s another reason it’s a good idea to ask about potential mold-causing problems. The seller may know of these conditions without being able to confirm there’s actual mold growth.

Professional Mold Testing

Should you get an expert’s opinion? Unfortunately, unlike tests for lead paint, tests for mold are difficult to conduct and expensive. And according to the U.S. Environmental Protection Agency (EPA), testing for mold isn’t usually necessary when it’s visible on surfaces. Most people will end up relying on the detection methods discussed above.

However, if you suspect mold is present in the home, but none is visible, you might elect to hire a professional mold testing company. These companies test the air in and around the home. They can also dig into walls and take samples, which they later test in a laboratory. Testing the air usually costs several hundred dollars. If the company takes wall samples, the cost will be even higher.

You can use the results from mold testing in two ways when negotiating a home purchase:

  • You can add a mold-related contingency to your offer which states that if mold problems are discovered, you can back out of the agreement.
  • If the testing company finds a significant mold problem, you can use this to negotiate a lower price on the home or get the seller to agree to pay for the cost of mold removal.

How to Fix Mold Problems

Dealing with a mold problem is a two-step process. First, remove the mold itself, plus any parts of the structure (walls, carpets, and so on) that the mold has damaged. Second, take steps to discover and fix the source of the moisture.

Step One: Removing the Mold

Recent and relatively small mold growths can often be fairly easily removed by scrubbing with detergent and following up with a combination of bleach and water, then allowing the area to dry completely. (If a problem is really that easy, though, you may wonder why the seller didn’t just take care of it himself.) Be sure to wear protective gear and keep the area well ventilated.

If the problem has been festering for some time, or is inaccessible (within a wall, for instance) you may have to enlist the help of a professional contractor. The contractor may have to do some serious work, such as ripping up carpeting and subfloors or tearing down walls to access the mold. (Replacing these materials will add to the cost of remediation.)

Hiring a contractor to remove mold. Nowadays, many contractors and handymen claim they are mold detectors (ads such as  “Mold Busters” and “Got Mold?” are common). But don’t automatically hire a company that bills itself as a “professional mold detector” or “licensed mold remediator.” In fact, there are no legally-imposed standards or licenses for handling mold repairs (unlike removing lead paint and asbestos). To determine if a particular contractor is qualified to do mold removal, do some homework.

  • Ask about the contractor’s practical experience with mold removal.
  • Find out if the contractor follows any professional guidelines or recommendations. Although no widely-accepted standards exist for handling mold remediation, most contractors who regularly remove mold follow the guidelines in the EPA’s publication, Mold Remediation in Schools and Commercial Buildings (you can get this free publication online by visiting the EPA’s website at and typing the publication name in the search box).
  • Look for contractors who hold genuine remediation licenses for lead and asbestos — these contractors may be your best bet, because they are already specializing in environmental hazards.

Step Two:  Removing the Cause of Mold Growth

The next step in your mold-riddance campaign is to find out where the moisture came from and stop its intrusion. If you don’t, the mold may simply regrow. Unfortunately, this part of the process can be expensive. Repairing a leaky roof, a basement prone to flooding, or a weak pipe behind a bathroom wall can be more expensive than removing the mold itself.

Should You Buy a House With Mold Problems?

If you find a house and discover it has mold problems, should you buy it anyway?  You’ll have to decide whether the cost of removing the mold and fixing the source — both in time and money — is worth the price you’ll pay. If you have an inspection contingency and the mold is revealed as part of the inspection, or if you have a specific mold contingency, you have a bargaining chip. You can ask the seller to reduce the asking price, to fix the problem, or you can choose to walk away from the deal.