Concrete basement floors became popular after World War II. Unfinished, they are a source of dust, mold, and mildew. Even sealed or finished concrete floors can be dusty, dirty, and stained.
You should clean your concrete basement floors once a year to remove dust, dirt, and cobwebs. If your basement has any leaks, you may have to clean out mold and mildew first.
Here are some useful ideas on how to clean concrete floors in the basement.
How to Clean Unsealed Concrete Basement Floors
Unsealed concrete is porous, meaning it can absorb grease from food, oil, and other debris, causing stains. To prevent staining, wipe or clean up spilled liquid as soon as possible. Cleaning stains off concrete after they set in can be difficult.
If you’re ready to clean your unsealed concrete floor, follow these steps.
Remove Loose Dirt
Sweep and/or vacuum all loose dirt and debris from the concrete floor. Dusty floors are more difficult to wash. Check the floor for cracks and other damage that need repairs before the final cleaning.
Note: Do not vacuum or sweep mold.
Remove Mold and Mildew
Trying to sweep or vacuum mold or mildew will spread spores throughout the basement and start new colonies – you need to kill the mold before removal. Open the windows before tackling mold. You can choose from many mold and mildew removers or use bleach mixed with water.
Spray the mold areas liberally with mold killer. Give it a few minutes to work (follow the manufacturer’s directions), then scrub it off with a stiff brush. Rinse and let dry. The mold will be dead, so you can vacuum it. You may have to repeat the process.
Note: The bleach/water mixture has the potential to discolor concrete.
Clean Stained Areas
Liquid laundry detergent is one of the least expensive but most effective stain removers. Pour it undiluted on the stain, scrub well with a stiff nylon brush, rinse with clean water, and check the results.
If the stain needs more work, mix baking soda and water into a paste and scrub it onto the spot. Or use a 50/50 vinegar/water mixture. Rinse and check the result.
Note: Do not use a wire brush. It can scratch concrete.
Get Rid of Efflorescence
Efflorescence is a term that describes white powder-like stains on concrete floors and walls. It forms when water with undissolved solids leaks through concrete and evaporates. You can remove it with a stiff nylon brush, wet rag, or wet mop.
Note: You should mark and seal the leaks after the floor is clean and dry.
Eliminate Rust Stains
To remove a rust stain on your concrete basement floor, pour undiluted white vinegar on it and let it sit for 20 minutes. Then, scrub with a stiff nylon brush, rinse clean with water, let dry, and inspect the results. If necessary, repeat the process.
Try a commercial product if you still have not removed all of the rust. Follow all instructions – some products claim to work on stains that have been there for years.
Note. Rust stains also happen because of leaks or high humidity. If they are caused by leaks, seal them after the floor is clean and dry.
Remove Oil and Grease Stains
To remove oil and grease stains from your concrete basement floor, pour dry baking soda onto the oil. Don’t be shy. Use lots. After it has absorbed as much oil as possible, pick it up with a broom and dustpan. Mix baking soda and a little water into a paste and apply with a stiff nylon brush to remove the rest of the stain. Rinse off and soak up the residue. Laundry detergent also works if you don’t have baking soda.
You can find many commercial degreasers that claim to work on old oil stains. Follow all manufacturers’ directions. Most degreasers use petroleum distillates. They are not as benevolent as baking soda, so wear a respirator and safety glasses.
Wash the Entire Floor
Wash the entire floor with washing soda like Borax and hot water. (Use two ounces of Borax per gallon of water.) Use a mop or nylon bristle brush to clean. The Borax will dissolve and remove any residual cleaning agents. Use a wet mop to pick up any remaining Borax, then dry mop the concrete.
Last Chance Cleaners for Your Concrete Basement Floor
Try these final options if all else fails to remove stains and grease.
Muriatic acid is another name for hydrochloric acid. It is serious stuff that can cause severe burns and permanent damage to the lungs, eyes, and skin. Wear a hazmat-type coverall, gloves, goggles, and a respirator. Use with extreme care and follow all directions.
Trisodium Phosphate (TSP)
TSP is a strong cleaner that removes oil, grease, mold, and mildew. It even removes paint from concrete. TSP is very caustic. It has been banned in some states.
Note: Phosphate-free TSP alternatives claim to work just as well as the original. I have never used them, so I have no opinion.
Concrete Cleaning Services
The last and most expensive option is to call a professional. Tell them your problem and try to get quotes from three companies. Make sure they include a total price and complete scope of work.
How to Clean Sealed Concrete Basement Floors
Cleaning a sealed concrete basement floor requires a vacuum cleaner and mop every week or two. Epoxy, stain, paint, and even wax (like our basement concrete) require little maintenance and are easy to keep clean.
Be aware that mold and mildew can appear or reappear on finished concrete floors. Basements are humid and sometimes leak. Damp spots where the floor finish is missing or where the floor meets the wall provide suitable mold-growing environments.