3 min readEveryone knows bathrooms are prime spots for mold growth. Showers, tubs, sinks, and toilets introduce moisture into homes, so homeowners must pay close attention to those areas. That said, they’re not the only places susceptible to mold growth. In fact, the areas homeowners rarely see can be some of the easiest to overlook.
“The biggest tell is usually smell before sight,” says Sam Hickerson, founder of RestoreAdvisor.com. “A musty odor that doesn't go away no matter how much you clean is often the first sign, and it can show up weeks before you'd ever see visible growth.”
Below, learn about five places around the house that deserve a closer look when checking for hidden mold.
Behind and Under Appliances
Large appliances can conceal a surprising amount of floor and wall space and aren’t often moved from their spots to check for mold growth. Refrigerators, dishwashers, and washing machines sit near water connections or other potential sources of moisture, making them worth checking periodically. Because of their bulky nature, a small leak or condensation can stay hidden for a long time, allowing that buildup.
“In my experience, the spots that surprise homeowners most are behind and under appliances, especially refrigerators and washing machines, where condensation builds up, and nobody looks for months at a time,” says Hickerson.
Behind Walls, Wallpaper, and Cabinets
Finished walls can hide moisture from plumbing or water entering from another part of the house. Cabinets and furniture can make some areas even harder to inspect because they obscure the wall surface.
It’s not always about scanning for visible mold. Wallpaper can conceal changes underneath the finished surface, so look for red flags like peeling, bubbling, staining, or another questionable changes.
“A lot of mold grows where you can't see it, such as behind drywall or wallpaper, inside HVAC ducts and systems, under carpeting, behind cabinets and furniture, inside wall cavities around plumbing, and even beneath flooring materials,” says Cadence Denoto, founder at Verified Remediation.
Under Carpet and Flooring
Even if a floor looks dry, there can be signs that moisture has reached the material underneath. Carpet padding can retain moisture, allowing leaks or spills to work their way into the flooring. Look for signs of warping, staining, or an unusual smell as part of your routine mold inspection. These symptoms may warrant a closer look, especially if the room has had a previous leak or other moisture problem.
“I also see it a lot under carpet padding along exterior walls, where a small temperature difference causes condensation to collect slowly enough that nobody notices until the carpet starts to smell,” says Hickerson.
Around Exhaust Fans and in Attics
An exhaust fan may look fine from inside the room, but meanwhile, moisture is causing trouble in areas you can’t easily see. Attics can also develop mold problems that are easy to overlook.
Depending on what you store up there, how easy it is to access, and whether it’s finished or unfinished, homeowners may only visit an attic occasionally, meaning problems can go unnoticed longer than they would in a frequently used room.
“One of the most common places hidden mold shows up is the rubber gasket where the bathroom exhaust fan meets the ceiling, especially when that fan dumps into the attic instead of venting through the roof,” says Denoto. “Another one is Cladosporium, which keeps growing in the cold, which is why it turns up inside refrigerators, which most people think is ‘safe.’”
Near Plumbing and Inside Wall Cavities
A dripping pipe doesn't always create a visible puddle. Water can soak into cabinets, walls, or ceiling materials before homeowners realize there’s a problem. Pay attention to changes around plumbing fixtures and nearby walls.
“Bubbling paint, drips, ceiling water stains, dripping pipes, damp basement walls, leaky toilets are a few examples of some maintenance issues that should be a red flag if you are concerned about mold growth," says Russell Vent, vice president of Paul Davis Restoration in Rochester, NY. “Water damage is the most important indicator that there may be mold growing, especially if it is on a porous material, like drywall. On the surface of the drywall, you may only see yellow water staining, but if the moisture source is coming from behind the wall, that painted surface of the drywall will often be more resilient to allowing mold growth since it has a raw fibrous backing. There may be hidden growth within the wall or ceiling cavity.”
