How Long Does it Take for Black Mold to Grow

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Black mold

As Joe and Cathy Cunningham found out the hard way, it can take mold less than three days to transform itself from “barely detectable” into a source of pungent smells and sickening viruses.

Joe, Cathy, and Mold

Joe and Cathy Cunningham had been through what they call “the drill” before. They knew exactly how to clean up their rec room after it filled with a few inches of water following a steady weekend rain. However, something was different about this episode.

When Cathy arrived home after work one evening, the smell of mold was most noticeable to her. She asked Joe to inspect the area, which he dutifully did several times but found nothing amiss. It was only after they both walked through the door after a three-day weekend away that they knew something was very wrong.

The smell of mold was overpowering to them.

Their Allenwood home had been “closed up” for days, meaning for three days and nights; their warm and damp rec room was not getting proper airflow. And that combination of excessive humidity and poor ventilation had turned their home into a hotbed for mold.

Worried, Cathy and Joe promptly called a builder friend who confirmed their worst suspicions. He found an abundance of mold—and presumably black mold—growing in a dark, hidden, and poorly ventilated wall cavity in their rec room.

It’s what Cathy calls a “cautionary tale” that “begins and ends” with a sage piece of advice: Getting rid of mold, thoroughly and permanently, is a highly specialized job, which requires “confident expertise” – of the kind that she and her neighbors find in GreenWorks. Experts agree.

“This job may be too difficult or dangerous for you,” warns the Centers for Disease Control and Prevention (CDC). The CDC has a good reason for issuing the warning.


Mold is dangerous, and if you don’t take proper precautions, you can feel irritation in your eyes or on skin. In more severe cases, allergic reactions and infections can develop. People with a weak immune system are at a greater risk.

Cleaning mold yourself just isn’t worth it. Even the CDC recommends homeowners to “get help from experienced and qualified professionals if you can.”

What is it that makes mold so scary? Let’s try to understand by learning a little about this tiny organism.

Learn the Basics

Mold consists of tiny microscopic organisms that are found outdoors and indoors.

  • Outdoors, mold expedites the natural process breaking down leaves and trees.
  • Indoors, mold usually doesn’t cause a problem until the spores land on a moist surface. At this juncture, the spores can quickly multiply and produce allergens that trigger allergic reactions.

Black Mold Is Sometimes Black

mold, in particular, thrives on moisture and true to its name, can appear largely black. However, this slimy substance also can be greenish-black in appearance, and be surrounded by pools of white and gray.

Black Mold Smells like Commingling Mildew

mold remediation procedures nj

The smell of black mold is distinctive, commingling mildew with a must. The odor is usually most noticeable after it comes into contact with a surge of air, such as when it is pushed through a home’s ducts, or after people have not breathed their indoor air for a period of time, such as in Joe and Cathy’s case.

Detecting Black Mold Is Difficult

Despite all appearances, discerning whether the mold is actually black mold is a bit trickier. Only a lab test can confirm the presence of black mold, and anyone who pre-judges its existence is only guessing; another reason why expert advice is vital.

But Cleaning Black Mold Is Vital Because It the Risk to Your Health

Black mold grows quickly, and the distinctive odor usually follows within 48 hours after a flood or other mishap involving an influx of moisture or water.

By this time, black mold often makes its presence known. It can “sneak up on you,” as Cathy says, in ways that can mimic allergy symptoms, including:

  • Coughing and sneezing
  • Eye, nose, throat and skin irritation
  • Fatigue
  • Headaches
  • Runny nose
  • Upper respiratory irritation

Left untreated, black mold can trigger:

  • Breathing difficulties’
  • Nausea, vomiting or diarrhea
  • Impaired concentration
  • Bladder or kidney pains

In very worst manifestations, black mold can be toxic, which is why Cathy is actually grateful that it smells as bad as it does.

Find the Solution in Greenworks

New Jersey residents turn to GreenWorks for expert mold remediation because we are, at heart, an environmental company that has convened the very best talent in the fields of building biology, ecology, and site remediation.

While there is no black mold problem that we haven’t encountered—and counteracted— we also know that no two homes are alike and that each one deserves our “Midas touch” of personalization.

For example, as much as we exude confidence in our ability to rid any home of black mold, we also know that we must address the root cause so that a mold outbreak does not reoccur. As the U.S. Environmental Protection Agency says, “If you clean up the mold but don’t fix the water problem, then most likely the mold problem will come back.”

While GreenWorks obviously cannot prevent future downpours and flooding, we can—and do—help our customers take preventive flooding measures and show them how to control day-to-day moisture in their homes. And we take pride in the fact that we educate our customers about exactly what steps to take should they experience another flooding event.

As Joe and Cathy learned, the “drill” can be both dramatic and traumatic. But with GreenWorks at your side, it will always end on a safe and healthy note.

This article was originally published on May 27, 2015, Updated on September 26, 2017

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Victor Coppola

Victor Coppola is a Building Biologist with decades of diverse environmental experience spanning natural resource management and contaminated sites to Indoor Air Quality (IAQ) and building hygiene matters. He focuses on the three most prevalent issues degrading today's built environment: Moisture Odor & Mold (M.O.M.). Mr. Coppola and his Team are sought out by individuals and professionals concerned about IAQ to those actually suffering from Biotoxin Illness. His hybrid blend of environmental interests and services enable him to give a unique perspective into today's changing environment. Think your home is killing you, better call Victor and his Team at GreenWorks.
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