How to Remove Mold from Concrete Floors

A dirty concrete floor suffering from mold.
What You'll Need
Rubber gloves
Scrubbing brush
Wet/dry vac
Trisodium phosphate

Mold can be harmful to your health, so it is important to know how to remove it from all sorts of surfaces, including concrete floors. If mold appears, it is vital to get rid of it quickly, as the longer it sits, the more it will spread and the harder it will be to get rid. However, unless the mold has been sitting on the concrete floor for quite a while, removal is not an especially difficult job.

Step 1 - Scrub With a Broom

Put on rubber gloves and a dust mask before you begin to remove mold because cleaning can stir up harmful spores that can be detrimental to your health. Then, mix up water and detergent (use a detergent that doesn’t contain ammonia) in a bucket at a ratio of four parts water to one part detergent. Pour about half of this solution on the concrete floor and work it over the deposits with a broom. This will help loosen the mold and make it easier to remove. Cover as large an area as you can.

Step 2 - Mop

Empty the bucket and refill it with clean water. Mop the area, allow it to dry, and see how much mold is left. You will have removed quite a lot by adding the solution to the floor but it is unlikely you will have cleared all of it. If any remains, you will need to take further action.

Step 3 - Add Bleach

To remove the rest of the mold, you will need to use bleach. In the bucket, mix up a solution containing one part bleach to 10 parts water. Make sure the area is well-ventilated, and then pour some of this solution on the mold and begin to loosen it with a scrubbing brush. Use the wet/dry vac to remove most of the water as you work; you don’t want the area to be too wet since moisture is one of the primary causes of mold.

After you’ve scrubbed, mop the area again and allow it to dry. If there is still mold on the concrete floor, you’ll need to stronger solution of bleach to remove it. Mix a new solution, this time with one part bleach to four parts water. Scrub the area again, and use a wet/dry vac to keep most of the water away from the floor. Mop up with clean water and allow to dry. In the event there is still some remaining after all of this, don't worry; there's still a solution.

Step 4 - Use Trisodium Phosphate

The final stage for getting rid of mold deposits involves another mixture of bleach and water. This time, however, you will need to add trisodium phosphate at a ratio of about half a cup to every two gallons of water and bleach solution.

Once again, scrub thoroughly but use very little of the liquid mixture. Vacuum away as much water as possible, and when you’ve finished, mop the area with clean water and allow it to dry. This should remove any mold left and ensure that it doesn’t return.

TSP is toxic and should not be ingested. Hands must be thoroughly washed after handling.

Step 5 - Determine the Cause

After you’ve removed the mold, you will have to find the cause of it; otherwise it will just grow back. Check for leaks in the ceiling or walls or for cracks in the concrete itself. If any are present, they will have to be fixed to prevent further problems.