How to Identify Mold vs. Mildew in Your Home

Mold and mildew are two common household nuisances that can seriously impact your home’s indoor air quality. While they may look similar to the untrained eye, mold and mildew are actually quite different. Learning how to identify and remove mold vs. mildew in your home is key to maintaining a healthy living environment.

What Is Mold?

Mold is a type of fungus that spreads through the release of microscopic spores. There are thousands of species of mold, and they can be any color – green, black, yellow, orange, red, brown, pink, or purple. Mold grows on organic materials in damp, humid environments with poor ventilation.

Some of the most common places to find mold growth in homes include:

  • Bathroom tiles and grout
  • Basements and crawlspaces
  • Attics
  • HVAC systems
  • Window sills and frames
  • Drywall, wood, and insulation
  • Carpets and upholstery

If left unchecked, mold can rapidly multiply and spread. Prolonged exposure to high levels of household mold may cause respiratory issues or allergic reactions in sensitive individuals.

Health Effects of Mold Exposure

Some potential health effects associated with mold exposure include:

  • Congestion, runny nose, coughing
  • Wheezing, trouble breathing
  • Red, itchy eyes
  • Rashes, hives
  • Headaches, dizziness
  • Asthma attacks

People with asthma or compromised immune systems are most vulnerable to mold’s effects. Seek medical attention if you experience severe or persistent reactions after exposure.

Signs of a Mold Problem

Watch for these common signs that may indicate a mold issue:

  • Visible mold growth – fuzz, spots, patches, or discoloration
  • A musty, earthy smell
  • Damp surfaces or moisture buildup
  • Condensation on windows and walls
  • Peeling paint or drywall
  • Warped floors or buckling walls

Take action at the first signs of mold to prevent further growth. Even small areas of mold can release spores that spread.

What Is Mildew?

Mildew is also a type of fungal growth that can affect your home. However, there are a few key differences between mold and mildew:

  • Appearance – Mildew is flat and powdery, whereas mold is fuzzy or bushy. Mildew is usually light to dark gray, or black in color.
  • Cause – Mildew is caused by excess moisture. Mold can grow with lower humidity levels than mildew requires.
  • Surfaces – Mildew is most common on natural fiber materials like cotton, linen, leather, and paper. Mold prefers damp organic materials.
  • Odor – Mildew smells like musty laundry, not the earthy/musty odor of mold.
  • Growth habit – Mildew grows superficialy on surface fibers, while mold sinks roots below the surface.
  • Spread – Mildew does not release spores like mold. It spreads through contact and moisture.
  • Health effects – Mildew is less likely to cause allergic reactions compared to mold. But both can aggravate respiratory issues.

Where to Find Mildew

Check these moisture-prone spots in your home for signs of mildew:

  • Window frames and sills
  • Bathroom tile grout
  • Shower curtains and bathroom mats
  • Upholstery, mattresses, and carpets
  • Leather goods and books
  • HVAC systems

Controlling moisture is the key to preventing mildew growth.

How to Identify Mold vs. Mildew

Now that you know the difference between mold and mildew, here are some tips for identifying which you may have in your home:

Examine the Growth Closely

  • Mold – If the growth has visible fibers, fuzz, or branching/spiderweb-like tendrils, it is likely mold. The color can help indicate the type.
  • Mildew – Check for a flat, powdery growth without fibers. It may be gray, black, white, or another pale color. Wipe a cloth over it to differentiate – mildew will come off as a stain, while mold won’t wipe away cleanly.

Consider the Location

  • Mold – Finds its way into damp organic materials anywhere in the home. Typical spots include drywall, carpets, tile grout, and insulation.
  • Mildew – Grows on surfaces with direct and prolonged moisture contact like window frames, shower walls, linens, and leather.

Smell for Clues

  • Mold – Smells earthy and musty, like dirt. The scent is stronger when affected materials get disturbed.
  • Mildew – Smells like stale, musty laundry and lacks the soil-like scent associated with mold.

Assess Surface Condition

  • Mold – May cause structural damage, leaks, warped surfaces, or spongy drywall as it penetrates materials and spreads.
  • Mildew – Tends to sit superficially on the surface fibers of affected materials without sinking in or causing underlying damage.

Consider Health Reactions

  • Mold – More likely to cause respiratory issues like sinus congestion, running nose, coughing, and wheezing due to released spores.
  • Mildew – Lower risk of allergic reaction. Mainly causes irritation and discomfort. Seek medical advice for any persistent reactions.

Monitor Growth Speed

  • Mold – Can spread rapidly under ideal damp conditions. Growth may visibly enlarge day-to-day.
  • Mildew – Spreads slowly by contact rather than reproductive spores. Growth is gradual over time.

By carefully inspecting, identifying clues, and comparing characteristics, you can determine whether you are dealing with a mold or mildew problem. When in doubt, consider hiring a professional mold specialist to test and identify growths. Proper identification is key to effective and safe removal.

Dangers of Mold Exposure

Although mildew poses some health risks if left unchecked, mold tends to be more concerning in the home. Here’s an overview of the most common dangers linked to household mold exposure:

Allergic Reactions

Inhaling airborne mold spores can cause respiratory issues like wheezing, chest tightness, coughing, and nasal congestion in those allergic to mold. Mold exposure can also irritate asthma. Reactions may occur right away or be delayed.

Respiratory Infections

Some dangerous molds like Stachybotrys chartarum release mycotoxins that can cause inflammation and irritation in lung tissue, increasing infection risk. Those with compromised immune function are most at risk.

Skin Infections

Direct contact with mold may lead to cutaneous mold infections, causing symptoms like redness, swelling, itching, and ulcers on the skin. People with weakened immune systems are more vulnerable.

Mold Toxicity

Myotoxic black molds like Stachybotrys can produce harmful mycotoxins. At high exposure levels over time, these toxins may build up in the body, leading to neurological issues, organ problems, and other dangerous effects.

Asthma Triggers

Mold exposure can worsen asthma and trigger attacks in mold-sensitive individuals. Even mild exposure may cause chronic coughing, wheezing, and difficulty breathing in asthmatics.

Chronic Fatigue

Research shows links between mold exposure and increased risk of chronic fatigue issues. Headaches, memory problems, nausea, and fatigue are common complaints. The reasons are still being investigated.

Do not take mold lightly, especially if you have respiratory issues or a compromised immune system. Consult a doctor at the first signs of any reaction after mold exposure. Prompt removal is essential.

Dangers of Mildew Exposure

Although mildew does not release airborne spores or penetrate materials like mold, it can still pose health hazards:

Allergic Reactions

Inhaling air close to mildew growth may trigger nasal congestion, sneezing, headache, and irritation in those allergic to mildew. Reactions are typically less severe than with mold allergies.

Asthma Triggers

Like mold, mildew may aggravate asthma symptoms and increase sensitivity to other asthma triggers. Wheezing, tightness in the chest, and coughing are common complaints.

Respiratory Discomfort

Prolonged exposure to extensive mildew growth may cause general respiratory irritation and discomfort even in those without allergies. Symptoms include nasal congestion, coughing, and sore throat.

Skin Irritation

Direct contact between mildewed surfaces and bare skin can cause irritation, redness, and itching. Keep wet mildewed fabrics away from direct skin contact.

Minor Illnesses

Extensive mildew exposure over time may potentially lead to headaches, nausea, and fatigue in sensitive individuals, though less severely than with heavy mold exposure.

Monitor your space for mildew spread. While impacts are lower than mold, removing mildew helps improve respiratory comfort and eases irritation.

Health Risks by Type of Mold

There are thousands of mold varieties, some more hazardous to health than others when exposure occurs. Here are some of the most common indoor molds and their associated risks:


  • Appearance – Dark brown, black, or gray; grows in small colonies
  • Health risks – Allergic reactions, asthma attacks, respiratory infections


  • Appearance – Various colors; thick, wooly texture
  • Health risks – Allergic reactions, respiratory issues, organ infections in immunocompromised


  • Appearance – Olive green to gray; forms clumps and hair-like tendrils
  • Health risks – Potential carcinogen; linked to neurological issues


  • Appearance – Olive green, brown, or black; velvety texture
  • Health risks – Allergic reactions, asthma triggers


  • Appearance – Shades of green, blue, gray; dense, brush-like texture
  • Health risks – Allergic reactions, asthma triggers, respiratory discomfort

Stachybotrys (toxic black mold)

  • Appearance – Black; slimy, wet sheen
  • Health risks – Most dangerous; mycotoxin producer; can cause chronic illnesses

Identifying the type of mold growth in your home helps assess level of health risk based on that species’ properties and your sensitivities. When uncertain, collect a sample for professional lab analysis and identification.

How to Test for Mold

If you suspect a mold problem but can’t identify the growth, consider getting laboratory testing done to analyze a sample:

Hire a Professional

A certified mold inspector can take samples safely using protective gear. They have the proper tools and expertise to pinpoint the mold type and extent of growth. Professional mold testing typically costs $300-$500.

DIY Mold Test Kits

For a more affordable option, purchase a do-it-yourself mold test kit for $30-$100. Follow all safety precautions when collecting samples. Submit to a lab per kit instructions.

Duct Tape Method

Simply place duct tape over the suspect area, peel it off to pick up a sample, and send to a lab. Use gloves and limit exposure. Cost starts around $30 for analysis.

Bulk/Surface Samples

Using gloves and a clean tool, collect some of the visible mold growth into a plastic bag. Try to get full thickness. Send to a lab for examination under a microscope.

Air Samples

More accurate but involved. Use an IMPAK or other specialized sampler to catch mold spores floating in the air. Send samples for lab analysis.

For accurate identification, send your samples to an environmental lab accredited by the AIHA, EMLAP, or ELAP. Testing pinpoints exactly which molds are present so you can assess risks and proper removal approaches.

How to Remove Mold Safely

Once you identify that you are dealing with a mold problem, it’s critical to take prompt action for safe, effective mold removal and remediation.

Supplies Needed

Gather these supplies before getting started:

  • Protective gear – gloves, goggles, N95 respirator mask
  • Plastic sheets and bags
  • HEPA vacuum
  • Scrub brushes, sponges, cleaning rags
  • Mold killing cleaner or bleach solution
  • Dehumidifier
  • Paint or plaster for repairs

Address Any Moisture Sources

Stop all moisture issues fueling mold growth – leaks, flooding, condensation, humidity. Mold can return quickly if dampness persists.

Isolate the Area

Seal off rooms with plastic sheets. Cover air vents. This keeps spores contained during removal.

Remove Visible Mold

Scrub surfaces using water, detergent, and/or disinfectant to remove all visible mold. Dry quickly afterwards.

Bag and Discard Affected Items

Discard porous, moldy furnishings, drywall, insulation and carpets bags for safe containment.

HEPA Vacuum Surfaces

Vacuum up all remaining debris and dust with a High Efficiency Particulate Air filtered model.

Apply Mold Killer

Use mold and mildew killing detergent or diluted bleach solution to disinfect all affected areas after cleanup.

Increase Air Circulation

Use fans, open windows, and a dehumidifier to dry the area completely and prevent recurrence.

Make Any Needed Repairs

Replace damaged drywall, carpet, or other building materials that were permeated by mold.

Take proper safety precautions during cleanup. Consider hiring abatement pros for large infestations or mold in wall cavities. Completely fixing the source moisture issue helps prevent regrowth.

How to Remove Mildew Safely

Mildew removal is very similar to mold remediation. Follow these basic steps:

Gear Up

Wear gloves, goggles, and a safety mask to protect yourself during the removal process. Open windows for good ventilation.

Clean Using Water and Detergent

Scrub mildew off surfaces using hot, soapy water. Repeat as needed until the growth fully lifts.

Rinse and Dry Thoroughly

Rinse away all soap residue. Allow all surfaces to dry completely to deprive mildew of moisture.

Disinfect with Bleach

Mix 1 part bleach to 4 parts water. Apply to the area and let sit 10 minutes before rinsing. This kills lingering spores.

Increase Air Circulation

Use fans, dehumidifiers, and open windows to keep problem areas ventilated and dry.

Wash Affected Fabrics

Launder mildewed curtains, towels, upholstery and other fabrics. Add bleach or disinfectant. Dry thoroughly before use.

Make Moisture-Proof Repairs

Fix plumbing leaks, improve ventilation, add exhaust fans, and dehumidify to control moisture that enables mildew.

With proper safety gear and some scrubbing, you can remove mildew buildup yourself. But if mildew persists despite your best efforts, contact a professional for stubborn growths.

How to Prevent Mold and Mildew Growth

Controlling moisture and humidity levels are the keys to preventing mold and mildew growth in your home. Follow these proactive tips:

Monitor with Hygrometers

Install hygrometers to monitor humidity levels. Keep indoor relative humidity under 50% to inhibit mold and mildew growth.

Increase Ventilation

Use exhaust fans, open windows and doors, and dehumidifiers to maintain air circulation and reduce moisture buildup.

Fix Plumbing Issues

Repair all water leaks and flooding immediately. Check under sinks, behind walls, and around tubs/showers for hidden moisture issues.

Improve Drainage

Slope soil and pavement to drain rainwater away from your home’s foundation. Keep gutters unclogged.

Insulate Cold Surfaces

Add insulation to exterior walls and cold water pipes to reduce condensation that allows mold and mildew to thrive.

Clean Laundry Room Promptly

Immediately wipe down washing machine doors, walls, and floors when finished. Don’t let puddles sit.

Add Mold Inhibitors

Consider applying Concrobium Mold Control or a similar product to problem areas to help prevent regrowth after removing existing mold and mildew.

With diligent moisture control and quick action at the first sign of mold or mildew, you can protect your home from fungal growth and its associated health hazards.

Frequently Asked Questions About Identifying Mold vs. Mildew

What does mold smell like?

Mold has an earthy, musty odor – like dirt and decaying leaves. The scent gets stronger when moldy materials become agitated or disturbed. An overwhelming mold smell indicates an active infestation.

Does mildew have an odor?

Mildew smells reminiscent of stale, damp laundry rather than the earthier, mustier smell associated with mold. The scent is especially noticeable in affected fabrics and textiles.

Can I identify mold just by sight?

It’s difficult to conclusively visually identify mold, which comes in many colors. Distinct fiber-like growth, fuzziness, and bushy tendrils are strong indicators of mold if present. Lab testing provides definitive identification.

Why does mildew look powdery?

The powdery appearance of mildew results from the structure of its cell walls. Mildew has a smooth, flat texture and grows superficially across the surface of affected materials instead of sinking roots like mold.

Is black mold dangerous to health?

Black molds like Stachybotrys chartarum release harmful mycotoxins and are associated with more severe health effects including chronic illnesses. Take special precautions when cleaning toxic black mold. Consider hiring professionals.

Can you get rid of mildew forever?

It’s extremely difficult to permanently eliminate mildew. The spores linger and wait for