home inspector mold

When you conduct a home inspection, you’re looking for anything and everything that could cause buyers problems with a property — both immediately and in the future. That’s a lot to cover, so great inspectors keep it all organized with a thorough inspection report and checklist that helps make sure no area or issue is missed.

In addition to scanning for visible issues with the structure, systems, and components of a house, home inspectors are also keeping an eye out for signs of problems that call for a closer look. And one of the biggest “hidden” issues that buyers and real estate agents are worried about is mold.

While a mold problem will ultimately need to be flagged and remediated by certified mold professionals, home inspectors come across the signs of mold frequently in their work. Visible mold growth is a problem you’ll want to flag for your clients and help point them in the right direction for a solution.

Here’s what you need to know.

7 signs of mold every home inspector should recognize

You cover a lot of ground during a home inspection. As you work, keep your eyes, ears and nose open for these common signs of a mold problem:

  1. Moldy, mildewy odors: Mold is often hidden out of sight, so one of the first signs people may notice is its odor. People experience scents differently, but the classic “mold smell” is often described as musty or earthy. Many people think basements always smell this way, but any dank odors should be noted and flagged for possible mold growth. 
  2. Black, sooty spots: Many molds are black or gray in color, so they may look like smudges of dirt on surfaces. Small spots may be mistaken for dirt, but as mold blooms and spreads, you may be able to notice a pattern. Many molds grow in circles and look like polka dots, while dirt or soot would likely be more randomly dispersed.
  3. Surface discoloration: While most people have a good mental image of black mold, it’s important to remember that mold comes in many colors. Black, gray and brown are the most common, but other molds may appear powdery and white, or a shade of blue-green. Mold growing under vinyl may even look pink, purple, or orange.
  4. Water damage: Signs of past water damage are red flags for the possible presence of mold. These include water spots and other discoloration of walls, ceilings and floors, peeling or bubbling paint and wallpaper, and bloated or bowed surfaces. There’s a good chance that mold exists beneath these surfaces, even if it isn’t visible to the naked eye.
  5. Water leaks: Keep your eyes and ears open for drips from faucets and other signs of plumbing leaks throughout the inspection. Active leaks in the pipes or around improperly sealed windows and doors are also places where mold is likely to take root. 
  6. Excess condensation: If you see condensation collecting on walls or windows, it’s a strong sign that there’s excess humidity and possibly an unresolved water issue somewhere — and excess water often leads to mold growth. 
  7. Odors from HVAC systems: Sometimes mold is present in ductwork or damp HVAC filters, which can lead to a musty smell that only occurs when heating or air conditioning units are running. If you test these systems, be sure to stay on the alert for any off-putting smells.

It’s possible for mold to grow in any part of a house, from the attic to the basement. However, some places are more susceptible than others. As you work through your checklist in each room, pay special attention for signs of mold in these areas:

  • Basements and crawl spaces: Underground areas are often more prone to dampness and are havens for mold growth.
  • Under sinks: Leaky plumbing often happens here, and mold likes to grow on wood surfaces inside dark cabinets.
  • Around and beneath large appliances: Refrigerators, washing machines, dishwashers, and air conditioning units may leak or drip, leading to excess water and mold growth.
  • Walls that enclose plumbing: In addition to kitchens and bathrooms, any wall that has pipes running through it is a spot to keep an eye out for mold.
  • Around windows and doors: Improper installation or rotting sills can let in rain or snow, which in turn leads to damp spots where mold can grow.
  • Carpeting: Fabric holds moisture for a long time, giving mold an opportunity to take hold. Whether mold has arisen from a chronic leak or a one-time flood, carpets are notorious hosts for mold infestations.   

Understanding mold damage and danger 

Though a bit of mildew in the shower is easily wiped away, other types of indoor mold are dangerous, with the potential to cause damage to the house as well as to the people who live there. Molds are a living organism — specifically, a type of fungus — that feeds on organic material. This means that, left to spread unchecked, mold can lead to the breakdown of wood, paper, and textiles in a home. Given a long enough period, mold can eat through wallpaper, the paper that covers drywall, carpet, wood and more.

It’s possible but unlikely that a home would have major structural damage caused by mold. The more pressing dangers are health problems related to mold exposure. Many molds are harmless, but some people are more sensitive to mold than others. 

The most common concern is a mold allergy. Mold allergies are triggered when people breathe in mold spores — the microscopic “seeds” that allow mold to reproduce when they land on damp surfaces. Just like dust and pollen, mold spores can trigger an allergic reaction when the body treats them as a harmful invader and rallies the immune system to fight to get rid of them. Common mold allergy symptoms include:

  • Runny nose and sneezing
  • Coughing
  • Itchy and/or watery eyes
  • Itchy nose and throat

Severe allergies can also lead to headaches, fatigue, and general misery, especially since you spend a good deal of your life in your home. Mold allergies can also be dangerous for people with asthma, who may find their symptoms worsen to the point of struggling to breathe during more frequent asthma attacks. 

The Centers for Disease Control (CDC) also warns that people who are immunosuppressed (typically due to a medication that reduces their immune system response) or who struggle with other respiratory conditions like COPD are also more likely to have an adverse reaction to indoor mold growth.

There is also widespread concern that stachybotrys chartarum, sometimes called black mold or toxic black mold, can cause significant respiratory problems in infants and young children. While the CDC maintains that no link between toxic mold and stachybotrys chartarum has been proven, many researchers remain concerned that black mold can cause “sick building syndrome” and lead to ongoing health problems for the people who inhabit them.

Responsibilities of the home inspector when mold is discovered

During a general home inspection, you will note a wide range of issues in the home. Abiding by the ASHI Code of Ethics — and by the rules of nearly all state governing bodies — requires you to note any immediate safety hazards to protect your clients. 

But mold isn’t always visible, and it’s not always a safety issue. So what’s a home inspector to do?

Visible mold should be noted in the home inspection report. If you’re not licensed or qualified to determine what type of mold it is — or if you have doubts that it is definitely mold, but a nagging gut feeling that it is — you can note the possible presence of mold in your report.  

Likewise, it may make sense to mention the possible presence of mold in locations where you have found visible signs of water damage throughout the home, or places with a notably musty odor. It’s always a good idea to review your state’s regulations and standards of practice for more information on what your home inspection license allows you to call out in your report.

It’s also a good idea to direct your client to the right professional to conduct a thorough mold inspection to get more accurate information about any potential mold problem. A licensed mold assessor can conduct a thorough inspection and mold testing to determine the amount of spores in the air and on surfaces. A mold inspector will typically also be licensed in mold remediation to remove or contain the problem. 

The bottom line

As a home inspector, you are often a homeowner’s — or potential homeowner’s — first line of defense when it comes to mold protection. Once you alert buyers to the potential for mold in the home, it’s up to them to take the next steps with a mold remediator to understand the extent of the issue and, if necessary, to move forward with mold cleanup. 

Looking for more helpful tips for home inspectors? The HomeGauge Learning Center is packed with useful information for both new and experienced home inspectors.