How to remove black mold from drywall

Remove black mold from drywall
Black mold on drywall

Apart from being an obvious health hazard, black mold on drywall is unsightly and can either indicate a water leak or indoor humidity problem. Here we will discuss methods of removing black mold from both finished and unfinished drywall. However, before any of these steps can be taken the cause of the problem first needs to be addressed.

Topics covered
  • What causes mold on drywall
  • Safety measures
  • Remove black mold from finished drywall
  • Remove black mold from unfinished drywall
  • Preventive measures

What causes mold on drywall

Before attempting to remove black mold from your drywall it would be best to first find out what caused it. The most common causes are either high indoor humidity levels which can easily be resolved or a leak, most often originating from behind the wall or above in the ceiling. If you suspect a leak use a moisture meter to check the moisture levels behind the wall of the affected area.

Only after first taking care of these problems can you safely start the remediation process without having to worry about whether or not the problem will return.

Safety measures:

  • Respirator: Spores are usually released into the air whenever disturbing mold so wear a N-95 respiratory mask to prevent breathing it in.
  • Windows: Open some windows in the room to get some fresh, clean air circulating.
  • Clothes: Wear clothes you can immediately throw into the wash once you are done cleaning because spores can easily stick to clothing.

How to remove black mold from finished drywall

Remove mold from finished drywall

The process behind removing mold from finished (painted) drywall is quick and easy compared to steps required for unfinished drywall. The coat of paint seals off all pores, therefore any mold on your wall is merely sitting on the surface and can easily come off. The only choice you really have to make in this regard is what type of cleaning agent to use. Here you will find a list of effective cleaning solutions but for this example we will use baking soda.

What you will need: A spray bottle, baking soda, white vinegar (optional), a soft brush, a dry towel and a vacuum cleaner (preferably a HEPA filtered vacuum).


Prepare the cleaning solution: As mentioned, we will be using baking soda in this example. Simply mix one part baking soda with 5 parts water. Baking soda works great on its own but feel free to add some vinegar to the mix for a bit of extra effectiveness and then transfer your cleaning solution to a spray bottle for ease of use.


Apply the solution to the affected area: Lightly spray the solution directly onto the affected area and let it soak for 10 to 15 minutes.


Scrub the affected area: Gently scrub the mold off from the drywall with a soft brush. You will notice it coming off easily.


Dry the area: Since water or humidity caused the problem in the first place it would be wise to not leave the wall wet. Dry the cleaned area off with a towel or cloth. You could also let an electrical fan blow onto the area for a few minutes. Done!


Vacuum: As an extra precautionary step vacuum the surrounding areas to get rid of any potential spores. A HEPA filtered vacuum cleaner would be ideal for this task.

How to remove black mold from unfinished drywall

Remove mold from unfinished drywall

Removing mold from unfinished drywall will take considerably longer and is somewhat more complex. There will be no actual cleaning involved – instead the moldy section will be cut out and replaced. If you do not like doing this type of work then its recommended you employ the services of a contractor.

What you will need: Plastic sheets, pencil, utility knife, some sandpaper, new piece of drywall, drywall compound and a vacuum cleaner (preferably a HEPA filtered vacuum).


Cover the immediate surrounding area: Since we will be disturbing the mold during the removal process we have to use plastic sheets to cover the surrounding areas. This is important since disturbing it could potentially release countless numbers of spores into the air. Also ensure the room is well ventilated and be sure to wear a respiratory mask so you do not breathe any spores in.


Remove the affected section of drywall: Carefully mark straight line squares with a pencil around the section you want removed. Once done take a utility knife and carefully cut straight along the lines and remove the section. Be careful where you place the cut-out section as it does contain mold.


Clean up any potential spores: After safely disposing the old wall section, throw the plastic sheets away and vacuum the entire area. It’s recommended you use a HEPA vacuum system but if you do not have one a regular vacuum is your next best bet.


Insert the new section of drywall: Measure the square hole you made and cut a new piece according to the measurement. If you like, you could paint the backside of the new piece with antimicrobial paint as an extra safety precaution because nothing is worse than mold that sits behind drywall. Insert the new piece into the opening but be sure it fits nice and tight with no openings. Secure it into position with screws to the wood beam behind the wall.


Finishing touches: Apply some drywall compound around the edges of the new piece. This will help secure it into position and close off gaps and cracks. Allow 24 hours for the compound to dry before using sandpaper to carefully even off the edges. Done!

Preventive measures

Mold resistant drywall: Use mold resistant drywall wherever possible. It costs a little bit more than the ordinary type and is not 100% foolproof but it does drastically reduce the risk and can save you from problems later. They are available from most good hardware stores and even your local Home Depot.

Paint wall surfaces: Drywall has a porous surface and this allows fungal roots to dig their way down. This is the reason why unpainted drywall has to be cut out and replaced whenever mold appears on it. To reduce the amount of work required make sure it’s painted. That way the pores are sealed and whatever mold is on it can simply be washed off. You can even take it a step further and use a mold resistant paint.

Indoor humidity: Consider investing in a good dehumidifier system to keep indoor humidity levels in check. This won’t only spare your walls from fungal growth but just about everything else too.

Moisture levels behind walls: In a lot of cases the problem is a leak behind walls where it’s out of sight. Periodically check the moisture levels behind drywall with the help of a quality moisture detector.

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