The 5 signs of mold in your home – spotting damp issues early will help beat it

Experts reveal the warning signs of mold to watch out for

A bathroom with wooden cabinets and dual sinks
(Image credit: Minthouse)

Damp and mold are not things we ever want to find in our homes, but it is important to keep an eye out for them regardless – even when we are sure our homes are safe from damage.

From musty odors to condensation, there are several signs you might have mold even if the pesky black spots themselves have not started to appear yet.

Here, professional contractors and mold removal experts reveal the five most common signs of mold in your home to help you get rid of mold quickly before it becomes more serious.

Signs of mold in your home

Treating the most common types of household mold starts by knowing where and what to look for. Understanding the early warning signs can help you deal with the problem swiftly and avoid disruptive construction work.

1. Discoloration

As with signs of mildew, the most obvious sign of mold is visible discoloration.

Jay Sanders, expert contractor and owner of Castle Dream Construction, says, ‘You should keep looking for visible discoloration on the ceilings, walls, or floors. If you find any sort of black, green, pink, or fizzy white patches, consider it a clear indicator.

‘Never ignore these small patches as mold can spread rapidly,’ he adds. ‘In fact, under ideal conditions, it can double in size every 24 hours.’

2. Damp, earthy smells

If you find yourself constantly asking why your house smells musty despite cleaning and ventilating, then it could be down to some hidden mold.

Peter Duncanson, VP of training and development at ServiceMaster Restore explains that, ‘When mold grows, it gives off a strong musty odor. You can notice the smell when your heater or air conditioner is running. The smell will usually be stronger around a vent that contains the mold growth.’

3. High humidity and dampness

If your home feels humid all the time, or you spot condensation on your walls, the chances are mold is growing somewhere in your space. The mold doesn't cause the humidity, but higher moisture levels provide perfect conditions for mold to develop – especially if you do not reduce humidity in a house quickly.

Russell Vent, VP at Paul Davis Restoration of Greater Rochester NY says, ‘As a general rule, mold needs consistent or prolonged moisture to grow – not simply a one-time spill or wetting. This is an important distinction, as a spilled cup of water on a couch isn’t going to grow mold for the most part, it will be wet and likely dry within a day. On the other hand, a leaky pipe under a sink that drips consistently over the course of two weeks before it is found is almost a guarantee for mold growth. Keep this in mind as you have concerns in your living space.

‘Water damage is the most important indicator that there may be mold growing, especially if it is on a porous material like drywall,’ he continues. ‘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.

‘A major sign that you have a high likelihood of mold growth will be condensation on your exterior windows or sweating of exterior walls. This could mean that your windows themselves may be failing or your home is simply too humid. These indicators may not seem like a huge deal when you first identify them, however they are a sign that you have a more universal, atmospheric problem going on, and if not rectified, could lead to a more serious problem.

‘Ensure you are monitoring the humidity in your home with the best dehumidifiers (especially in your basements). Mold thrives in environments above 55% relative humidity.’

4. Blistering or peeling paint and wallpaper

Before you fix peeling paint or wallpaper in your home, consider why it is blistering or peeling in the first place. Unless you have snagged it, the chances are mold is the culprit suggests Jay Sanders, expert contractor.

‘Keep checking the paint – be alert if you find peeling or bubbling. It usually signals moisture buildup behind the surface. You can check it by gently pressing on suspicious areas. If you feel the surface to be soft or spongy, then the moisture may have been trapped underneath.’

Fixing the paint or paper before dealing with the mold will lead to the problem getting worse, and the aesthetic damage recurring.

5. Allergy symptoms

Mold is one of the most common allergens that plague our homes, and regular household cleaning tips won’t tackle it until you use vinegar to get rid of mold for good.

Peter Duncanson of ServiceMaster Restore shares, ‘One of the biggest concerns regarding mold growth is the negative effects it can have on whoever is exposed to it. Breathing in mold spores can cause some people to suffer from health problems. They can experience coughing, sneezing, nasal congestion, itchy eyes, skin irritation, breathing concerns, headaches, and other allergy-like symptoms. These problems will only worsen the longer one is exposed to mold.’

If your allergies are suddenly worse than ever despite using cleaning tips for allergy sufferers, or you are experiencing allergy symptoms for the first time, it might be time to thoroughly check and treat your home for mold.


You shouldn’t limit yourself to only the most common places to check for mold. These signs can pop up anywhere in your home – even in rooms that don't deal with moisture such as kitchens and bathrooms. Water soaking through walls in excessively rainy seasons and a lack of ventilation can contribute to mold growth in any room of the home, so stay vigilant to avoid lasting damage to your property and health.

Content Editor

Chiana has been at Homes & Gardens for two years. She spends most of her time producing content for the Solved section of the website, helping readers get the most out of their homes through clever decluttering, cleaning, and tidying tips. She was named one of Fixr's top home improvement journalists in 2024.