Tips for Preventing and Detecting Winter Mold in Your House

Got an awful case of off-season allergies, windowsills that appear to be growing a five o’clock shadow, or tiny-but-telltale spots of discoloration on your drywall?

If you live in a cold climate, kicking up the heater during winter months doesn’t just keep you warm—it also helps to create a perfect environment for winter mold and mildew.

Not only are fungal infestations unsightly, but they can cause allergic reactions such as sneezing, stuffy noses, and itchy eyes. And, in the case of mold, can spread relatively unnoticed, quietly compromising the integrity and strength of your very walls.

To save you the cost of expensive repairs, here’s how to prevent unwanted mold and mildew this winter.

Mold vs. Mildew: What’s the Difference?

Mold and mildew have a lot of similarities. They’re both likely to grow in moist, warm areas and are adept at surviving on a wide variety of surfaces.

Additionally, they’re both fungi that aren’t welcome in your home. Both can cause uncomfortable allergy symptoms. And, of course, their presence is an indicator that excess moisture is present. (We’ll get to the three factors that help mold and mildew to thrive shortly.)

Technically, mildew is a type of mold. The difference? Mildew sticks to growing on surface areas and is simple to wipe clean whereas mold can grow undetected for months – destroying the surfaces it thrives on.

Visually, there are some significant differences. Mildew is recognizable by its flat surface which stays relatively flush with whatever it’s growing on. It can appear downy or powdery in texture, and, while it may start out white, generally ends up yellow, brown, or black.

Mold, on the other hand, can be any of a wider range of colors including green, yellow, brown, gray, or white. Instead of growing relatively flush with a surface, it’s distinguished by a fluffy appearance.

And, depending on where it grows, spots may appear separately – as in not connected – but in the same area.

Discerning whether a patch of fungi is mold or mildew is important since their differences are way more than skin deep.

Food, Warmth, and Moisture: The Three Musts for Mold and Mildew

Not to gross you out, but microscopic mold and mildew spores are everywhere—even in the air we breathe. However, the risks of mold and mildew increase come winter due to the difference in temperature between indoors and out.

That’s because fungi like mold and mildew require three things to thrive in your home: food, warmth, and moisture.

The “food” that mold and mildew require is any organic material (meaning that it contains carbon atoms) which can give it the energy to grow. This can be anything from the old bread on your kitchen counter to the cupboards on the walls, or even the cotton rug on your floor.

Warmth occurs when you crank up that aforementioned thermometer. But some areas that suffer from poor insulation, such as single-pane windows and outer-facing walls, can stay cooler than your home’s average temperature.

See Also: 11 Ways to Stay Warm for Less This Winter

Moisture that travels into your home basement, bathrooms, or kitchen will condense when it comes in contact with a cold area. That’s why you’re most likely to find mold or mildew on windowsills, baseboards, tile grout, and even in the back of closets.

The good news is that if you deprive mold or mildew of moisture, warmth, and food, you will stop it from growing.

The bad news? While mildew might be easily defeated, depriving mold of its needs won’t kill the spores that are already there.

Instead, deprived mold will just stay dormant and start growing again if they get moisture, warmth, and food – springing back to life within hours of a favorable shift in its environment.

Six Ways to Beat Mold and Mildew Before They Start

When all the right conditions are present, moisture, ample food, and a temperature between 41-100 degrees Fahrenheit, mold will begin growing within 24 to 48 hours.

However, it can often remain hidden until the spores have already affected large areas of your property and caused considerable structural damage.

That’s why the easiest way to beat these fungal culprits in the winter months is with prevention. Here’s how to limit moisture, remove tempting food sources, and keep an eye out for the first telltale signs of a winter mold problem.

1. Increase Air Circulation and Reduce Humidity

One cheap and simple step to reduce moisture is to use fans and open windows. By increasing the air circulation in rooms, cold air is less likely to condense in nooks and crannies.

If you live in a particularly cold climate, opening windows might not be an option. Instead, consider purchasing a dehumidifier to reduce the overall moisture inside your home.

Look for one that offers digital readings, which can help you to keep your indoor humidity level is below 40%.

2. Keep an Eye Out for Leaks That Can Let in Excess Moisture

Keep an eye out for leaks in common areas such as windows, exterior to interior doorways, and the surrounding areas by swamp coolers and skylights.

Not only should you be on high alert for leaks coming from the outdoors, but don’t forget to check your indoor plumbing as a possible culprit for excess moisture. Check for hidden leaks in areas such as under bathroom and kitchen sinks.

3. Repair Any Leaky Area Immediately

Mold and mildew can grow at a rapid pace. The longer you leave a leak unattended, the more likely you are to experience mold and the damage that comes with it.

In short, the moment you suspect or see a leak, fix it--or you might be stuck with paying for more expensive remediation.

4. Limit the Possible Areas Where Mold and Mildew Can Grow

Since fungi thrive on quick-to-decompose items such as books, piles of loose papers, or boxes of clothing, be strategic when storing these items.

The best areas for long-term storage area away from external walls or windows that invite condensation. Instead, pick a storage area that enjoys circulation to prevent the possibility of built up moisture.

Remember to also keep a close eye on the moisture in your bathroom and clean surfaces regularly as well. Because bathrooms can carry the most moisture in the home which naturally results in the most mildew.

5. Take Care to Keep Entryway Flooring Dry During Wet Weather

If possible, use area rugs or washable floor surfaces rather than wall-to-wall carpet in areas or rooms that have a moisture issue.

While it’s not usually a great idea to have carpeting in your entryway, if you live in a cooler, wet climate, renters often don’t have a choice.

In instances where you do have carpet up to the door, take care to vacuum the area regularly, inspecting the area for signs of any mold near the baseboards or where your carpet meets the wall.

6. Use Exhaust Fans in the Kitchen and Bathroom

Boiling water and taking steamy showers provide your home’s environment with plenty of moisture. Make sure not to slack on turning on exhaust fans, including the one in your oven’s hood, that can help reduce condensation from collecting.

It’s also helpful to leave exhaust fans on for twenty to thirty minutes after steaming up a room and wiping down moisture on the walls with a dry rag.

How to Find Suspected Mold Growth

We mentioned above that mildew is likely to appear in obvious places, including windowsills and bathroom caulking.

However, mold might not always be visible. Since mold doesn’t need light to thrive, it can grow within walls, behind molding, and in hidden corners throughout the home which can be more difficult to discover.

One reason to suspect mold is if you can smell a strong, musty odor in an area of your home. If you start to suspect hidden mold, try to pinpoint what area might be prone to water damage or condensation.

Again, kitchens and bathrooms, as well as areas around doors and windows, are the most susceptible, so make sure to check these areas for excessive moisture or mold growth.

What if you find what you think is mold, but aren’t completely positive?

Alyse Ainsworth, Home Safety Expert at A Secure Life provided the following handy tip to make sure that it’s mold you are battling – and not just dirt.

“There are mold test kits available for purchase, or you can save yourself a few bucks and try out a quick at-home test with some common household ingredients,” she suggests. “Try dabbing a cotton swab with bleach and apply it to the area you suspect to be mold.”

Alyse says that, if it remains black, then what you’re dealing with is most likely dirt. However, if it turns white, that’s a sure sign of mold or mildew.

You’ve Discovered Mold. What to Do Next?

Unless the growth is very minor, our research reveals that it’s probably best to hire a professional to remove it. That’s because, according to experts, natural cleaning solutions won’t do the trick.

Even bleach is considered too weak to eradicate mold spores, and household cleaners will only disguise the smell while giving the mold time to grow.

Fungicidal sprays are the only solution that can kill mold spores and the amount of chemical you’d need to remove mold can be equally hazardous to your health.

That’s why experts suggest that only the smallest of affected areas should be handled by homeowners. If you do decide to try and kill mold yourself, be sure to wear protective goggles, gloves, and a respiratory mask before applying a fungicide spray to mold spots.

However, if mold has found its way into your HVAC system, appears in multiple areas on your walls, or you’re already experiencing symptoms of mold exposure, it’s time to call a mold remediation expert.

Doing so saves you the possible health risks associated with handling mold – not to mention they’ll make sure that there are no patches left behind – or that your home isn’t damaged during the exploration process.

Depending on where you live, the cost can be between $500–$5000 for professional mold remediation. However, it might be covered by your homeowners or renters insurance.

How to Identify Trustworthy Mold Remediation Specialists

Mold remediation isn’t a task that can be handed off to any handyman. How to check that your potential contractor is a specialist before signing a contract?

Start by searching Google for local mold removal companies, visit their websites, read reviews, and ask for recommendations. Or, use a nationwide index that lists verified contractors such as Restoration Master.

Once you’ve chosen a company, call to confirm that any tech a company sends out will be properly licensed and that they have sufficient experience.

According to Restoration Master mold remediation expert Luke Armstrong, your best bet is to hire Certified Mold Remediation Technicians who have been trained and certified by the Indoor Air Quality Association (IAQA).

Additional questions you should ask include what kind of equipment is used and the contractor’s guarantee. (Double check under which circumstances mold that reappears would be deemed their responsibility.)

Remember, It’s Easier to Prevent Mold Than to Remove It

When it comes to discovering mold, homeowners face somewhat of an uphill battle. Instead of brick and stone, modern building materials are porous and susceptible to mold growth.

Additionally, energy efficient homes are made to be air tight while water pipes run inside walls while surrounded by insulation, creating a possible environment for mold. All these factors make detection difficult, so be sure to:

  • Ensure good air circulation, including cracking windows, running exhaust fans, and minding that air ducts are kept free of dust and debris.
  • Use a dehumidifier to reduce humidity levels to 40%.
  • Inspect your property at regular intervals to check that roof, foundation, plumbing, and HVAC systems are in good repair.

And remember, if you do find signs of mold, doing your research before hiring a specialist can save you money and headaches in the long run.

Learn how to shop around in Insider’s Tips: How to Find a Reliable Contractor.


Autumn Yates

Autumn draws from a reporting background and years of experience working remotely, while living abroad, to focus on topics in travel, beauty, and online safety.


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