Mold vs. Mildew: When To Worry and When To Clean

Not All Ugly Patches of Fungi Are the Same

Mold can ruin just about anything it gets its spores on. When you first spot a blotch of evil mold in the bathroom or the basement, is it time to burn down the house and start over? Or can you handle the problem yourself?

First, it’s important to know just how bad mold can be. Mold can cause difficulty breathing, eye irritation, sore throat, sneezing, rashes, confusion, fatigue and many other symptoms that seem flu or allergy related. Dangerous black mold can cause severe respiratory problems including bleeding in the lungs.

Put another way: Mold is bad news. Prevention and early detection are the best ways to fight back against this evil substance.

Understanding the Enemy

We think of a mold as four-legged stool that needs four things to stay alive and thrive: Air, water, food and a temperature between 41 and 104 degrees Fahrenheit. Knock out any legs of that stool, and the stool falls. But because mold can feed on a variety of surfaces (wood, fabric, even wallpaper) it’s difficult to remove the food source. And controlling temperature and oxygen can be nearly impossible. As such, one of the best ways to fight mold is drying the area with proper ventilation.   

Conditions required for mold growth:

  • Air
  • Water
  • Food
  • Temperature between 41 and 104 degrees Fahrenheit

Mildew: The Lesser of Two Evils

Mildew and mold are both fungi, but mildew is not as invasive or troublesome as other types of mold. Typically found in wet areas, mildew looks grayish-white and may turn brown. It’s flat and powdery and it’s an easier fungus to clean because it lives only on the surface of a material (such as bathroom tile). If you see powdery white specks collecting in the corner of a shower, you should be able to clean it away entirely with a cleaning product such as bleach or vinegar. (Use one cup of bleach per 1 gallon of water.)

Mildew can cause similar allergic reactions to that of mold, but because it’s easier to eliminate, it’s less of a threat. A little bleach can stop mildew dead in its track.

Typical Traits of Mildew:

  • Grayish-white or brown
  • Powdery appearance
  • Foul odor

Mold: Now You’ve Got Issues

The warning signs of a mold invasion are often hard to spot, which is why it can sneak up on a homeowner. The first clue you have mold is a foul odor. If you notice a musty, pungent smell, chances are good that mold is hiding somewhere nearby. Get out the flashlight and facemask, and start hunting.

Mold will appear fuzzier and darker than mildew, but it can grow in a variety of colors, from bright reds to dark, swampy greens. Because it can look like nothing more than a small patch of dirt, it’s easy to ignore mold problems until it’s too late. And like a cockroach, if you see one spot of mold on the surface, there might be much more mold hidden out of sight. For that reason, mold removal can be expensive and labor intensive.

Typical Traits of Mold:

  • Black, bright red to dark green
  • Fuzzy appearance
  • Musty smell

When In Doubt, Call For Help

Additional Resources: 

Tips for Identifying Mold Behind the Wall

How to Prevent Mold Growth After Water Damage

Small mold problems in the bathroom can be handled with a little elbow grease, but for larger, more invasive problems, always seek proper professional help. If you’re worried that the mold problem is too big for you to handle, or if there’s a chance more mold might be living elsewhere in your home, don’t hesitate to call a professional. According to, it can cost between $2,000 and $6,000 to clean mold from air ducts, crawl spaces, walls and attics.

Strike First: Preemptive Solutions to Mold Problems

Mold is a serious concern, and if you’re in the process of building or renovating a home, mold resistant products will help reduce your risk of encountering mold. Remember, mold loves moisture so keeping moisture out of your house helps keep mold out of your house. The fight against mold has become high-tech and scientific.

Here are the best ways to keep your house dry:

  1. Start from the outside of your house. Use a water-resistant membrane such as CertainTeed’s CertaWrapTM to keep the whole house dry.
  2. On the inside of your home, protect your walls. First apply a protective coating directly to the framework to inhibit the growth of mold in the wall cavity after it is sealed.
  3. Select a moisture managing insulation. CertainTeed’s insulation keeps yours walls dry year round using MoistureSense technology.
  4. Follow that with a mold-resistant drywall such as M2Tech® Mold and Moisture Resistant Drywall. This is especially important in areas with high moisture contents such as kitchens, baths and laundry rooms. AirRenew drywall also helps clean the air by absorbing formaldehyde.
  5. Don’t forget the walls behind decorative features like tile backsplashes or shower surrounds. While tile might seem to be waterproof, it is not. CertainTeed’s GlasRoc® Tile Backer protects tile installations and the walls behind from moisture intrusion.

When it comes to combatting mold and mildew at home it is particularly important to pay special attention to areas of high moisture including kitchens, baths, laundry rooms and basements. 

Next Steps

Visit our Moisture Management Solutions for more information on combatting moisture in your home and keeping your walls dry. Concerned you may have a mold problem? Let us put you in touch with a contractor that can help


Want more insider tips and practical solutions for improving your home? Sign up for our monthly email.