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How To Remove Black Mold From Shower Caulk

Mould is probably the most unwelcome element in any shower stall, and the unfortunate truth is that mold spores are present everywhere at all times. When the spores are given moisture and food, they will multiply at a staggering pace. Attacking the problem very early will prevent damage to the walls that support the shower tile and caulking. Black mold can be removed and recurrence can be prevented by following these steps.

Causes of Mold on Shower Caulking

black mold in shower caulkMould grows where moisture is present for long periods of time. When the relative humidity level in the bathroom remains above 60 percent due to poor ventilation, the spores that are present in any home will attach to the shower caulking and begin to multiply. Mould will feed on wood, soil, cloth or paper. Most of these substances are present in the bathroom all the time.

Remove Black Mold From Caulk

When black mold is noticeable on the shower caulking, take the following steps to stop the growth process and remove the mold from shower caulking:

Step 1: Protect yourself by wearing the recommended gear listed below.

Step 2: Ventilate the area by opening windows and the bathroom door. Turn on the bathroom ventilation fan and open a window, if possible. Keep the bathroom door open.

Step 3: Mix one cup bleach with one gallon of water.

Step 4: Fill a spray bottle.

Step 5: Remove towels from the area to prevent spots on the fabric.

Step 6: Spray the area that has visible black mold.

Step 7: Wait 30 minutes and then rinse with fresh water.

If the mildew does not wipe away, it could be growing within the caulk. If the mold has penetrated the caulk surface, the only answer is to remove the caulk and replace it with mold resistant caulk designed for bathrooms.

During this process, if you begin to feel light-headed, leave the area for a few minutes. For extensive jobs, work in small increments of time to reduce the impact of the cleaning solutions.

Clean and Disinfect the Area

remove black mold in showerAfter the mould has been removed, the rest of the surfaces of the shower must be purged of mildew spores to prevent re-growth of mold on shower caulking. One of the most effective ways to remove the invisible mold spores is to spray the entire shower stall with the bleach mixture and then rinse and dry the shower walls and fixtures. Perform this task just prior to leaving the house for at least 48 hours. When the shower is allowed to dry completely, the spores that are present will die. Then the mold prevention tips can be implemented with a completely clean shower stall.

Tools and Protective Gear

Closely follow these recommendations to protect yourself from mildew spores that will permeate the air during the mold remediation process.

  • Gloves and eye protection must be worn to protect the skin from cleaning agents and mould spores.
  • A mask to cover the nose and mouth must be worn to prevent the inhalation of mould spores that are dislodged from the surface of the shower wall.
  • Place the bleach and water solution in an adjustable spray bottle.
  • Have a full bucket of hot clear water available to rinse the surface with a clean sponge.
  • For extensive mildew removal, wear a disposable paper overall that can be discarded when the job is completed.

Prevention Tips

mold in shower caulkingMoisture reduction and control are the keys to preventing mold from growing on surfaces in the home. In very humid climates, proper ventilation and the use of air conditioning and de-humidifiers in the home will lower the humidity level to the preferred range of 30-50 percent relative humidity. In arid climates, outdoor air can be utilized to reduce the humidity level in the home. After every use of the shower, follow these recommendations to reduce the recurrence of mold.

Vented bathroom fan – Building codes have been updated to require one vented fan in every bathroom. Older homes are exempted from this requirement until the bathroom is remodeled. If there is a fan present, ensure that the exhaust pipe is vented to the outside of the home and not just into the attic area. Run the fan for one full hour after using the shower.

Remove wet towels – Instead of hanging towels on the racks in the same room, consider hanging the towels outside to dry or run them through the dryer. When mold is an issue, wet towels are one of the main sources of moisture and must be removed to lower the relative humidity level in the room.

Dry the shower stall – Water will cling to the shower tile and caulking during and after a shower. Use a towel to dry the shower walls and then remove the towel from the room.

Clean shower walls weekly – Use a cleaner that contains bleach to kill the mold spores that might have collected in the shower since the last cleaning. Follow the directions closely to use the cleaner properly and attain the best possible result.

Measure humidity – A small humidity meter can be purchased from the hardware store. Place the meter close to the shower and run the bathroom fan until the relative humidity level drops into the acceptable range of 30-50 percent.


Mold can pose dangers to people with respiratory diseases and allergies. Prior to attempting to remove the black mold from shower caulking, heed these warnings:

  • Wear all recommended protective gear.
  • Evaluate your personal ability to complete the project.
  • If the caulk must be replaced, do not start the project if enough time is not available to completely finish replacing the caulk. The shower will not be available for use if all the caulk has not been replaced and allowed to dry completely.
  • Do not delay! If you do not possess the ability to remove the mold, find a reputable professional to correct the problem.
  • Serious health problems can result from black mold.

Normal shower use creates enough moisture to encourage mould spores to attach to the shower wall and begin to grow. Take the recommended steps to prevent black mold from growing and causing damage to belongings and threats to health.