Mildew vs mold: How to tell the difference

The differences between two uninvited guests – and how to banish them

Key tips to remember

  • Mildew and mold are both fungi
  • Both thrive in moist environments
  • Both can cause damage to homes
  • Both can cause health problems
  • Take steps to remove and prevent both
Maintenance and Repairs

Let’s face it. Nobody ever invited mildew or mold to a party or was stoked when either one showed up. These ickiest of interlopers are closely related, and sometimes one can lead to the other, but if you have a pretty good handle on what they are and where they come from, you’ll be better at keeping them from making an appearance and causing a major buzzkill. 

As microorganisms of the fungi persuasion, mildew and mold can damage your home and cause health problems. While they share similarities, they also have distinct differences. Both can grow in, around and on just about any surface. Knowing the difference between mildew and mold is a great first step toward banishing them from your home and keeping them out for good.

Health problems

Anyone living in your home who is prone to allergic reactions is likely to react to even a minimal invasion of mildew or mold. Typical symptoms can at first seem like normal allergies but can quickly worsen and should never be ignored. From respiratory ailments to cold symptoms, headaches and even fever and breathing problems, mildew and mold can grow fast and cause serious health trouble, even for healthy adults who aren’t used to experiencing allergies. 

Among the worst strains of either microorganism, black mold (stachybotrys chartarum) can cause yet more severe health problems, like memory loss, mood swings, nervous system damage, phantom pains, auto-immune disorders and even depression. If you’re experiencing any of these symptoms and suspect your home has been infected with black mold or something like it, it’s best to have a professional evaluate your living space as soon as possible.

Mildew

Identifiable via its lighter shades of white and gray that gradually turn into flat, powdery little brown dots, mildew is in fact a surface fungus and an early stage of mold. Mildew dots are easy to spot, as they tend to spread outward instead of upward, remaining flat and looking like a sprinkling of powder on a flat surface, one you might be tempted to simply brush away. Thriving in humidity, mildew can even show up on plants. Mildew’s distinctive, musty smell is recognizable as that of sour socks or of wet laundry that’s been left too long in the washing machine after a load has run its course. If caught before it proliferates, mildew doesn’t usually leave lasting damage, though it can lead to more powerful strains of mold if left to grow.

Mold

Mold: white, fuzzy, green or sticky, also identifiable via its darker shades of yellow, red and black. Mold on a wall, floor, ceiling or furniture grows upwards instead of remaining flat. It can grow underground, sometimes looks like dirt and can be fuzzy or even slimy, indicating a more serious infestation of nefarious microorganisms. 

A more dangerous invader than mildew with the potential to destroy structures and impair organ and immune system function, mold is much more likely than mildew to cause lasting damage to parts of a home or to the long-term health of its inhabitants. Mold can grow in the dark and eat into its base, making it yet more difficult to eradicate. Compared to mildew, it really stinks like rot, as it’s more volatile. Under the right, moist conditions and with continuous food supplies, it can expand exponentially.

Causes of mold and mildew

Mildew and its gnarlier cousin mold love to grow in enclosed areas where moisture is allowed to thrive, which is why you find both so often in areas exposed to water damage, a situation these nasty little bugs live to exacerbate. Although some varieties of both tend to favor warmer temperatures, that is not a requirement for either to proliferate. For either to grow, all they need is a spore, which can grow with food, water and oxygen. 

The food source could be as simple as the walls of your home. Wet drywall is a delicacy enjoyed by mildew and mold spores across the world, and their spores can start to grow in less than 24 hours, if a water source is added to a food source and oxygen is available. This means that if your AC is venting cold air into a closed closet as you try to keep temperatures down in the heat of summer months, for example, you may be creating a perfectly moist environment for some disgusting, uninvited guests.

Eliminating mold and mildew

If you’d like to know how to get rid of the smell of mildew, as a general rule, it’s best to go after mildew (or mold) immediately, preventing it from spreading and impacting your home and family more than it already has. However, before you begin treating any mold or mildew, make sure you have eye protection, gloves and a mask. Other than this basic safety equipment, a bucket with hot water and a mild detergent might be all you need, although a 50/50 vinegar-and-water solution could work just as well, as would a weak solution of bleach and water. Make sure you use a new sponge, as you don’t want to spread spores. 

Get rid of the soggy, rotten, mildewed or molded materials, spray the remaining area with clean water to prevent spore movement, spray again with your cleaning solution of choice, and start scrubbing. Then let everything dry for at least two days and nights before disturbing the area or painting anything. Mildew should be easily scrubbed away with any of these solutions, but if you’re dealing with mold, you’re in a new ballgame. Some molds can be cleared away with the same solutions and methods, but black mold calls for a professional, as you won’t want to accidentally spread it into other areas of your home.

Preventing mold and mildew

Preventing mildew and mold centers around keeping your home dry and clean, with adequate ventilation, good airflow and unblocked vents. Aside from those general rules, it helps to use fans, dehumidifiers and to open your windows and get natural airflow throughout the home whenever possible. 

When it comes to mildew and mold, moisture is your enemy, so do your best to make sure it’s not trapped anywhere, like that stuffy, closed, unventilated shower, clogged dryer vent or weak stove hood.

Concluding thoughts

If you suspect you have an issue with mildew vs mold, don’t procrastinate. When spores are concerned, time is not your friend. If you want a clean, healthy home with happy, healthy inhabitants, you need to go after this stuff at its first sign to make sure it gets out and stays out for the duration of your stay. If you think your mildew or mold situation is out of control, never hesitate to call a professional for an estimate. Your home, your health and the health and safety of your loved ones is essential, so make sure all your parties are for invited guests only!

If you’d like to read more on this topic, check out our piece on how to prevent mold with proper system maintenance, and review our helpful tips and tricks for a magical spring cleaning.


The information in this article is intended to provide guidance on the proper maintenance and care of systems and appliances in the home. Not all of the topics mentioned are covered by our home warranty or maintenance plans. Please review your home warranty contract carefully to understand your coverage.
 

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