Does Bleach Kill Mold? How to Remove Mold on Walls to Ceiling*

Yes, bleach kills mold on hard, nonporous surfaces, and that's important. Mold can cause damage to your home and impact your indoor air quality.

More from Clorox experts

Mold on walls and ceilings is typically caused by excess moisture from sources like leaks, high humidity or poor ventilation. When damp conditions persist, mold spores can settle and grow surfaces — often spreading quickly. It's important to kill mold as it can cause damage to your home and significantly impact your indoor air quality and overall health. Note, if the mold has a surface area larger than 10 square feet, call a mold remediation professional.

Does bleach kill mold?

Yes, and it works by breaking down mold cells on surfaces. Knowing the right concentration of bleach is key to making your solution effective and safe. Read on to learn the correct bleach-to-water ratio for removing mold, straight from the experts at Clorox.

What does mold on the ceiling look like?

Mold on walls and ceilings often appear as black, green, gray, or brown spots or patches. It may look fuzzy, slimy, or powdery and can grow in clusters. Mold is commonly found in corners, near ceilings or around windows where moisture accumulates. Sometimes it’s accompanied by a musty odor even before it's visibly noticeable.

How long does it take bleach to kill mold?

The contact time for Clorox™ Disinfecting Bleach to kill mold on hard, nonporous surfaces is 10 minutes. It’s important to let the bleach solution sit during this time before scrubbing or rinsing. For best results, always follow up by drying the area thoroughly to prevent mold from returning. Always check the product label for specific instructions and test on a small area before use.

How much bleach is needed to kill mold?

To kill mold, mix ⅓ cup of Clorox™ Disinfecting Bleach per gallon of water. Always apply in a well-ventilated area and never mix bleach with other cleaners like ammonia or acids.

What should I use to remove mold on walls & ceiling?

What you need

How to get rid of mold on walls & ceiling

  1. Prep area

    Open windows and ventilate the area where you are working to circulate fresh air.

    open window ventilation

  2. Pre-clean surface

    If mildew is heavy, pre-clean by wiping away as much as you can before bleaching.

    Hand pressing down on yellow sponge.

  3. Mix bleach solution

    Using your measuring cup and bucket, measure ⅓ cup Clorox™ Disinfecting Bleach per gallon of water (1500 ppm available chlorine solution).

    Hand holding translucent container pouring clear liquid.

  4. Apply solution

    Wearing gloves, apply the solution to the affected area with a sponge or brush.

    Tip

    Use a spray bottle for more convenience.

    Person cleaning floor tile grout.

  5. Wait 10 minutes

    Allow it to sit in contact with the mildew for 10 minutes. If needed, reapply the bleach and water solution to keep the surface wet.

    White mechanical kitchen timer with dial set to 2 minutes.

  6. Rinse

    Rinse the affected area with clean water.

    Hand holding a handheld showerhead with water spraying.

  7. Air dry

     Allow to air dry. You may use a fan for quicker drying time.

    Tip

    If you used a spray bottle, be sure to rinse it out.

    open window ventilation

How to prevent mold

To prevent mold, you’ll want to minimize the presence of moisture. Fixing leaks, using dehumidifiers and improving ventilation can help, especially in bathrooms and kitchens. Keep surfaces dry and clean, and use exhaust fans when cooking or showering. Regularly check for condensation or damp spots to catch mold early.

Tips for how to clean mold on washable walls & ceiling with bleach

  • Know the right bleach-to-water ratio: https://www.clorox.com/learn/bleach-dilution-ratio/
  • Use freshly mixed solutions — bleach degrades over time when diluted.
  • Never mix bleach with vinegar, ammonia or any other cleaner — it can create dangerous fumes.
  • Wear gloves and ensure good ventilation during use.
  • See our step-by-step guide to removing mold from shower walls.

Frequently Asked Questions

What causes mold on the ceiling?

Mold on the ceiling or walls is typically caused by excess moisture and poor ventilation. Common sources include roof leaks, plumbing issues, high humidity, or steam from showers and cooking. The root issue is usually a combination of dampness and lack of airflow, which creates the perfect environment for mold growth.

Is bleach or vinegar better to kill mold?

Only bleach is registered with the EPA to kill mold. Vinegar has not been proven to be effective on mold with the EPA, a nationally recognized authority on mold claims.

At what temperature does mold die?

Mold begins to die at temperatures above 140°F (60°C), but sustained heat is required to be effective.1 Simply warming an area isn’t enough—high heat must reach deep into porous materials to fully kill mold. For lasting results, combine heat with moisture control and proper cleaning.