Is it Mold or Mildew?

Many people commonly refer to various building molds as “mildew", and numerous mold cleanup products use the words “mildew” or “mildewcide” in their name and instructions. Although interchanging the words mold and mildew is acceptable by many, what’s the truth of the matter?


Mold or Mildew

Mold is a distinct species and genus within the fungi family. (Did you flashback to biology class?) It’s one of the main decomposition methods that nature utilizes. Molds or fungus feed upon dead and decaying organic matter, and so they enhance the decaying processes of nature on fallen trees, plants, dead animals, leaves, etc. Without life forms like mold, we’d be buried under piles of dead stuff. So that’s great. But problems arise because mold doesn’t know the different between dead trees in the forest and a wet wall stud in a home. And since mold spores are always floating around, they easily find what they need to grow and reproduce; food, moisture, and darkness.

Mold can also grow on many nonporous materials such as concrete and brick. And with the right temperature, moisture and food, mold will grow most anywhere. A rolling stone may gather no moss, but one sitting still sure can. Although it's more prevalent and grows more quickly on porous surfaces like drywall and wood (because there's more food), over time even a large area of concrete or brick can be covered by it. This is especially true in high humidity when the temperature between the surface and the air are slightly different.


Mildew is likewise a segment of the fungus family , but a different genus. In fact, mycologists (those who study the branch of botany dealing with fungi) regard it a parasite because it feeds only on living plants.

They’re divided into two sub-groups:

  1. Oidium-Erysiphe, familiarly named Powdery Mildew
  2. Peronosporaceae, familiarly named Downy Mildew

These take the form of a white or gray powdery or splotchy deposit on plant leaves and stems and are often caused by poor air circulation within or around the plant, and dampness or high humidity. And that’s an important distinction because most buildings will never have a mildew infestation unless they're growing a ton of plants inside. But since the majority don’t, mildew is rarely an issue with indoor contamination.

Many times, the term mildew will be used generically to refer to mold growth that has a flat growth tendency. In other words, it doesn't grow roots and thus it's non-destructive and easily scrubbed away. It, too, will grow anywhere there's enough moisture, such as bathroom sinks and showers, basement walls, or fabrics.

For these reasons, a mold expert or a home inspector should never lump mold and mildew together or say that they’ve found mildew growing in or on a building.

The Need to Remove It

The presence of mold, while unsightly, can also lead to ongoing issues, from respiratory distress to property damage. You need to pay immediate attention to any signs of mold, assess the situation and decide on a swift course of action for removal or remediation.

Your best bet is to call Cyclone Kleen Up. We offer mold removal and mold remediation services in Colorado. We are licensed by the State of Colorado as a General Contractor, and we can provide a FREE mold inspection, property loss evaluation, and detailed estimation for our mold clean up services.