12 Common Types of Mold

12 Common Types of Mold in Homes: What Every Homeowner Should Know

Mold isn’t just an unsightly inconvenience—it can quietly threaten your family’s health and your home’s structural integrity. Often hiding in damp corners, behind walls, under floors, or inside HVAC systems, mold can go unnoticed until it becomes a serious problem. And while many homeowners think of mold as just one thing, the truth is that there are dozens of different types of mold, each with unique characteristics, risks, and treatment approaches.

In this post, we’ll walk you through 12 of the most common types of mold found in homes, explain how to identify them, and most importantly—what to do if you find them. If you’re a homeowner concerned about indoor air quality or past water damage, this guide is essential reading.

Why Identifying Mold Type Matters

Mold identification isn’t just academic. Different mold types grow under different conditions and pose varying levels of health risks. Some can cause allergic reactions or asthma flare-ups, while others—like black mold—can produce dangerous mycotoxins. Proper identification allows for effective removal, tailored treatment, and a safer home environment.

Let’s take a deep dive into the most common culprits.

1. Stachybotrys chartarum (Black Mold)

The Dangerous One

This is the infamous “toxic black mold” you’ve probably heard about. Stachybotrys thrives on cellulose-rich materials like drywall, wood, and paper, especially after prolonged water damage.

Color & Texture: Dark green to black, slimy

Health Risks: Produces mycotoxins that can cause respiratory issues, chronic fatigue, headaches, and more serious complications with long-term exposure.

Where It Grows: Basements, bathrooms, behind walls, near leaks or floods

2. Aspergillus

The Common Invader

Aspergillus includes over 180 mold species, many of which are found in homes. It’s one of the most prevalent molds indoors.

Color & Texture: Varies—green, yellow, white, or black; powdery or fuzzy texture

Health Risks: It can cause allergic reactions, lung infections (especially in those with compromised immune systems), and aspergillosis

Where It Grows: Air ducts, insulation, walls, damp areas

3. Cladosporium

The Allergy Aggravator

Cladosporium is an airborne mold that often causes allergic symptoms and thrives in warm and cool environments.

Color & Texture: Olive green to brown or black; suede-like texture

Health Risks: Triggers asthma, sinus infections, and skin rashes

Where It Grows: Wood, textiles, bathroom walls, HVAC systems

4. Penicillium

The Fast Spreader

This mold spreads quickly and can indicate severe indoor moisture issues. Some Penicillium species are used to make antibiotics, while others are dangerous allergens.

Color & Texture: Blue, green, or yellow; velvety texture

Health Risks: Respiratory issues, sinus infections, asthma attacks

Where It Grows: Wallpaper, carpets, mattresses, ductwork

5. Alternaria

The Outdoor-Indoor Crossover

Alternaria is often found outdoors but can be carried inside through windows, vents, or on shoes. It’s one of the most common allergens.

Color & Texture: Dark green or brown with a fuzzy texture

Health Risks: Asthma triggers, respiratory distress, skin irritation

Where It Grows: Bathrooms, under sinks, around windows, in showers

6. Fusarium

The Cold-Tolerant Contender

Unlike many molds, Fusarium can grow in colder environments, making it a threat even in winter.

Color & Texture: White, pink, or reddish; cottony texture

Health Risks: Can cause skin infections and, in rare cases, serious conditions like fusariosis in immunocompromised individuals

Where It Grows: Wet carpets, humidifiers, HVAC systems

7. Acremonium

The Toxin Producer

Acremonium often starts off moist and then turns into a powdery substance. Due to its toxic potential, long-term exposure should be avoided.

Color & Texture: White, gray, pink, or orange; powdery

Health Risks: Immune system suppression, organ damage, mycotoxin exposure

Where It Grows: Cooling coils, humidifiers, window sealants

8. Chaetomium

The Drywall Destroyer

Often mistaken for black mold, Chaetomium thrives in areas with major water damage. It’s a strong indicator that drywall or insulation may be compromised.

Color & Texture: Starts off white, turns gray or black; cotton-like texture

Health Risks: Skin and nail infections, allergic reactions

Where It Grows: Drywall, ceilings, leaky roofs, basements

9. Mucor

The Fast-Growing Fungus

Mucor grows in thick patches and can spread rapidly in damp environments. It’s often found near HVAC systems and causes health issues if inhaled.

Color & Texture: White to gray; cottony or wool-like texture

Health Risks: Breathing problems, eye irritation, mucormycosis in rare cases

Where It Grows: HVAC systems, ducts, water-damaged insulation

10. Trichoderma

The Hidden Hazard

Trichoderma is highly adaptable and often resistant to antifungal treatments. It can cause serious structural damage as well as health risks.

Color & Texture: White with green patches; wooly or fuzzy appearance

Health Risks: Pulmonary and sinus infections, immune suppression, mycotoxin exposure

Where It Grows: Wet surfaces, wallpaper, carpet, drywall

11. Ulocladium

The Leak Indicator

Ulocladium is commonly found in homes with extreme moisture problems. Its presence often points to undetected water leaks or floods.

Color & Texture: Black or dark brown; similar in appearance to Cladosporium

Health Risks: Allergies, hay fever symptoms, skin irritation

Where It Grows: Kitchens, bathrooms, basements, behind tile grout

12. Serpula lacrymans

The Wood Destroyer

Known as dry rot fungus, this mold doesn’t pose significant health risks but can devastate wooden structures and furniture.

Color & Texture: Yellow or mustard brown; dusty or spongey texture

Health Risks: Rarely dangerous to health, but very damaging to homes

Where It Grows: Wood beams, subfloors, joists, wooden furniture

Signs You Might Have Mold in Your Home

Even if you can’t see mold, your home might still be hosting it. Common signs include:

Musty, earthy odor
Peeling paint or wallpaper
Water stains or discoloration
Persistent allergies or respiratory symptoms
Warped walls or ceilings

Is All Mold Dangerous?

Not all mold is toxic, but any mold in your home should be taken seriously. Even so-called “harmless” mold can worsen allergies, damage building materials, and lead to costly repairs if ignored.

People with asthma, allergies, weakened immune systems, or chronic lung conditions are especially vulnerable to mold-related health issues. Infants, the elderly, and pets can also suffer adverse effects from mold exposure.

Mold Remediation: What to Do If You Find Mold

Discovering mold can be alarming, but there’s no need to panic. What matters most is acting quickly and wisely.

Here’s what to do:

Don’t disturb the mold. Scrubbing or sweeping can release spores into the air.
Identify the source of moisture. Mold can’t grow without water.
Ventilate the area. Open windows and doors to improve airflow.
Call a professional mold removal service.

DIY mold removal is only safe for small, isolated patches of non-toxic mold. Professional remediation is a must for larger infestations or toxic varieties like Stachybotrys.

Why Professional Mold Remediation Matters

Professionals have the training, equipment, and protective gear to:

Identify mold species
Locate hidden infestations
Contain spore spread
Remove contaminated materials safely
Prevent mold from returning

You don’t want to cut corners on this. A botched DIY attempt can worsen the problem, putting your health and home at risk.

Final Thoughts

Mold in the home is a common problem, but it doesn’t have to become a crisis. By understanding the 12 most common types of household mold, you’re better equipped to recognize potential threats, act fast, and protect your family’s health.

From allergenic varieties like Cladosporium to more dangerous strains like black mold or Acremonium, each type of mold carries its own risks and requires a specific approach for removal.

If you’ve noticed musty smells or discoloration on walls or are dealing with recurring allergies or respiratory issues, mold may be to blame—and it’s time to take action.

Don’t let mold take over your home or jeopardize your health. If you suspect mold or have experienced water damage, contact the professionals at Discount Water & Mold Removal.

Our expert team will assess your situation, safely eliminate mold at the source, and restore a healthy, clean living environment. Fast, affordable, and trustworthy.

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12 Common Types of Mold