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4 Types of Mold That Can Grow Inside a Water-Damaged Home

Water damage can be a nightmare. Bad enough that the unwanted water can damage your home’s interior walls, ceilings, and floors, but it wreaks havoc on your furnishings and personal possessions. The aftermath of water damage can also be a long-term problem that affects your home’s safety and the health of you and your family.

When wood, drywall, concrete, and other building materials get wet and stay wet for more than a few hours, they become a breeding ground for millions of different types of organisms. The vast majority of these lifeforms are entirely harmless and so small that they’re never even seen. One type, though, can turn your home into a health hazard: mold.

Of the more than 21 million asthma sufferers in the United States, it’s estimated that more than 20% developed asthma because of mold exposure in the home. Certain types of mold can contribute to other dangerous health conditions, including memory loss, depression, and severe allergies.

In this article, we’ll discuss some of the many types of mold that can grow in your home as a result of water damage, explain the hazards caused by each, and show you why a trusted water damage reclamation company is your best bet for making sure water damage doesn’t turn into bodily damage for you and your family.

What Types of Mold Grow in Water Damaged Homes?

“Mold” is a broad term that describes the reproductive form of thousands of different types of fungi. Molds can develop on almost any surface but grow best on a surface made up of their favorite foods. Some molds grow best on foods, some grow best on fabrics, but some of the most dangerous thrive on things that are high in cellulose – like wood, paper, fiberboard, and some kinds of dust – or mineral content like ceramic and drywall.

Under normal circumstances, the spores that mold grows from land on these materials all the time, but when the surface is dry, there’s not enough water present to allow the spores to take hold and grow. But when that surface has been soaked in water, all the required elements are present for even a single spore to turn into a full-blown mold problem.

There are about a dozen different types of mold commonly seen in water-damaged homes:

  • Alternaria
  • Acremonium
  • Aureobasidium
  • Chaetomium
  • Cladosporium
  • Fusarium
  • Stachybotrys atra
  • Mucor
  • Aspergillus
  • Penicillin
  • Trichoderma
  • Ulocladium
Woman with handkerchief in front of a mould spot

What Are the Most Dangerous Mold Types in Water-Damaged Homes?

Of the twelve types above, four have the highest potential for causing health problems for a home’s occupants.

Stachybotrys atra (Black Mold)

This species is the most feared common mold, responsible for the vast majority of mold-related severe health problems and deaths. While it’s commonly referred to as “black mold,” Stachybotrys can be greenish, grey, or even orange in tint. It’s a slimy mold that usually looks a bit like tar. In addition to allergies and other problems caused by breathing in the spores from black mold growth, the fungus also releases a number of toxic chemicals called mycotoxins that can cause severe respiratory and neurological conditions and other significant health problems.


More commonly found on mineral surfaces like tile, concrete, and drywall or furniture and fabrics, Cladosporum starts as tiny black, yellow, or green dots that grow until they merge into a large patch of brownish-black and olive-green growth. Breathing in Cladosporium spores can cause severe allergies and asthma in people with a sensitivity to molds.


While typically harmless to most people, the spores of Aspergillus molds can be dangerous when inhaled by people with lung disease or a weakened immune system. The spores can cause infections in the lungs and other organs that these individuals may not be able to fight. Aspergillus growths tend to be blackish, with white and yellow appearing in places throughout the mold colony.


Alternaria grows thick and has an almost velvety surface that sometimes has long, hairlike projections. While more common in the outdoors, Alternaria can thrive inside a home’s basement, crawlspace, or attic and can cause severe respiratory distress for asthma and allergy sufferers.

How Do I Know Which Type of Mold My Home Has?

If you can see the mold, you can usually identify it by its appearance, and there are dozens of sites online with photos of different molds that you can compare. Molds don’t always grow out in the open, however, and you may need to rely on some other cues to tell you that your home has developed a mold problem:

  • Smell: Most molds will put off a musty or even a foul odor like rotting vegetables.
  • Dust: When molds release spores, your home can be filled with persistent, musty-smelling dust that is hard to get rid of.
  • Health effects: If you and your family or people visiting your home begin to show allergy or asthma symptoms that clear up when they leave, that may indicate a mold problem.

How To Get Rid of Mold

Mold removal is tricky. Just the process of scrubbing away the visible signs of mold can cause the organism to release more spores that will eventually settle back onto the surface and start the whole cycle over again. Removing black mold can be an incredibly dangerous undertaking, requiring special respirators and protective gear to avoid contracting a fungal infection.

If your home has suffered water damage and you’re now experiencing a mold issue, your best bet is to contact a licensed, reputable water damage repair company. The professionals there will have the tools and experience they need to locate and remove existing mold growths – even those hiding inside your walls, attic, basement, or crawlspace – and return your home to a safe, healthy condition.

If a Flood Has Caused Water Damage in Your Home, Contact AfterCare Restoration Right Away to Begin Mitigation and Restoration. We Work With NFIP and Private Carrier Flood Insurers: 215.515.1000

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