Where to Start: Assessing the Size and Spread

The first step is to figure out whether you can handle the mold yourself or need to call a professional. The U.S. Environmental Protection Agency (EPA) recommends that homeowners clean mold patches smaller than 10 square feet on their own—that's roughly a 3-by-3-foot area. Anything larger, or mold in your HVAC system, insulation, or drywall, should be handled by a mold remediation contractor.

Before you start, put on safety gear: an N95 mask (not a cloth mask), disposable gloves, and eye protection. Open windows and doors to ventilate the space. If the mold is in a bathroom or basement, run a dehumidifier or fan to pull moisture out of the air while you work.

Look closely at what you're cleaning. Black or green fuzzy growth on tile, painted walls, or hard surfaces is usually safe for you to tackle. If the mold has soaked into drywall, wood framing, or insulation, stop and call a professional—those materials absorb moisture and the mold likely extends deeper than you can see.

Key Takeaways

  • Clean mold patches smaller than 10 square feet yourself using a mask, gloves, and eye protection; anything larger requires a professional contractor.
  • Use a mixture of detergent and water, a commercial mold cleaner, or diluted bleach (one cup per gallon of water) on hard, non-porous surfaces.
  • Scrub the mold away completely, then dry the area thoroughly with towels or a fan to prevent regrowth.
  • Fix the moisture source—leaks, poor ventilation, or high humidity—or the mold will return within weeks.
  • Wear an N95 mask, gloves, and eye protection while cleaning, and ventilate the room by opening windows and running a fan.

Cleaning Solutions That Work on Hard Surfaces

For tile, painted drywall, glass, and other hard surfaces, you have three main options. The simplest is detergent and water: mix a few drops of dish soap into a spray bottle of warm water, spray the mold, let it sit for 10 minutes, and scrub with a stiff brush. This works well for light mold and is safe to use around children and pets.

If detergent doesn't remove the mold completely, try a commercial mold cleaner like Tilex, Clorox Mold & Mildew Remover, or Lysol Mold & Mildew Killer. Follow the label instructions exactly—most require you to spray, wait 10 to 15 minutes, and scrub. These products are stronger than soap and water but still safe on tile, grout, and painted surfaces.

For stubborn mold, diluted bleach is effective on non-porous surfaces like tile and glass. Mix one cup of bleach into one gallon of water (never mix bleach with ammonia or other cleaners—the fumes are toxic). Spray the solution, wait 10 minutes, scrub, and rinse thoroughly with clean water. Do not use bleach on wood, fabric, or painted drywall, as it can damage or discolor them.

The Scrubbing and Drying Process

After explore your chosen cleaner, use a stiff-bristled brush or an old toothbrush to scrub away the mold. Don't just wipe it—mold has roots that extend into porous material, so you need to scrub hard enough to dislodge it. For grout lines, an old toothbrush works better than a large brush because you can get into the narrow spaces.

Once you've scrubbed, rinse the area thoroughly with clean water to remove all cleaner residue and mold spores. Use a clean cloth or paper towels to dry the surface completely. If the area is large or very wet, run a fan or dehumidifier to speed up drying. Mold thrives in moisture, so the faster you dry the surface, the less likely it is to return.

If mold returns in the same spot within a few weeks, the moisture source is still active. Do not keep cleaning the same area without fixing the underlying problem—you'll be fighting a losing battle.

Finding and Fixing the Moisture Source

Mold grows because moisture is present. Common sources include roof leaks, plumbing leaks, poor bathroom ventilation, basement seepage, and high indoor humidity. Walk around the moldy area and look for water stains, soft drywall, or a musty smell that spreads to other rooms.

In bathrooms, mold usually means the exhaust fan isn't working or isn't being used. Turn on the fan during and for 20 minutes after showers. If you don't have a fan, install one or open a window. In basements, check for cracks in the foundation, standing water, or a sump pump that isn't draining properly. In kitchens and under sinks, look for leaking pipes or slow drains that back up.

If you find a roof leak, plumbing leak, or foundation crack, repair it before cleaning the mold. If you find high humidity (above 50 percent), use a dehumidifier or improve ventilation. These fixes take time and sometimes money, but they're the only way to stop mold from coming back.

When to Call a Professional Mold Remediator

Call a professional if the mold covers more than 10 square feet, if it's in your HVAC ducts or insulation, if it's in drywall or wood framing, or if you have health concerns like asthma or a weakened immune system. A mold remediator will assess the full extent of the problem, identify the moisture source, and remove contaminated materials safely.

Before hiring, ask the contractor for references and verify they're licensed in your state (requirements vary). Get a written estimate that includes the scope of work, the materials they'll remove, and how they'll prevent regrowth. Some contractors offer a post-remediation inspection to confirm the work is complete.

Do not assume that any mold you see is the only mold present. Professionals use moisture meters and thermal imaging to find hidden moisture and mold behind walls and ceilings. This is especially important in basements, attics, and crawl spaces where mold can grow out of sight.

Preventing Mold from Coming Back

After you've cleaned the mold and fixed the moisture source, keep humidity below 50 percent. Use exhaust fans in bathrooms and kitchens, open windows on dry days, and run a dehumidifier in basements or damp rooms. Wipe down shower walls and tub surrounds after bathing to remove standing water.

Check your roof, gutters, and downspouts twice a year to make sure water is draining away from your house. Inspect under sinks and around toilets monthly for leaks. In basements, keep the floor clear so you can spot water damage early. The goal is to keep indoor humidity steady and fix leaks before they create the wet conditions mold needs to grow.

Frequently Asked Questions

Is black mold dangerous?

Black mold (Stachybotrys) is no more dangerous than other molds—the color doesn't determine the risk. Any mold can trigger allergies or asthma in sensitive people. If you have respiratory problems, let someone else clean the mold or wear a properly fitted N95 mask and ventilate well.

Can I paint over mold?

No. Paint traps moisture and allows mold to keep growing underneath. Clean and dry the surface completely, fix the moisture source, and wait a few days to confirm the mold doesn't return before painting.

What's the difference between mold and mildew?

Mildew is a type of mold—it's usually white or gray, flat, and powdery, while other molds are fuzzy and darker. Both are cleaned the same way: detergent and water, commercial cleaner, or diluted bleach on hard surfaces.

Do I need to throw away items with mold on them?

Hard items like plastic or glass can be cleaned and reused. Porous items like fabric, paper, books, or drywall that are heavily molded should be thrown away because mold roots go deep and cleaning won't remove all of it.

How long does it take for mold to grow back after cleaning?

If you've fixed the moisture source, mold shouldn't return. If it does within a few weeks, the moisture problem is still active—check for new leaks, poor ventilation, or high humidity and address it before cleaning again.