How To Clean Stained Cement or Concrete

Clean

Maintain your home’s value by cleaning stained cement floors and patios. You don’t need any special equipment, just a few common ingredients.

Photo of empty garage with stained concrete and cement floor

How to Clean Stained Cement or Concrete

As with any household task, the best method depends on the type of mess you’re cleaning. If your concrete or cement has multiple stains, you’ll need to treat each one separately.

Time required: Varies

What to Know Before You Start

Cleaning a stained cement or concrete floor isn’t a quick task, but it’s not a difficult one, either. Before you get started, there are a couple of important things to remember:

1. Do not mix cleaning methods. Combining different solvents can cause toxic fumes and lead to serious health problems. Treat each kind of stain one at a time and give the floor enough time to thoroughly dry between methods. (Find out more about cleaning products that aren’t safe to combine.)

2. Use good ventilation. If you’re working in the garage, open the doors. If you’re working indoors, open windows. You’ll be stirring up a lot of dust and possibly other irritants that have soaked into the cement. Protect your lungs. If you have asthma or allergies, it’s a good idea to wear a particulate respirator mask, too.

Equipment You Need:

  • Push broom
  • Bucket
  • Stiff brush
  • Spray bottle (some stains)

Materials You Need:

  • Baking soda
  • Hot water
  • Liquid dish soap
  • Oxygenated bleach (some stains)
  • Cornstarch or clay cat litter (some stains)
  • Distilled white vinegar (some stains)
Man using push broom to clean dirty cement sidewalk

General Cleaning for Dirty Cement

Before you begin cleaning cement stains, general cleaning of the entire surface.

  1. Sweep the surface with a push broom to remove debris.
  2. In a bucket, combine 1/2 cup baking soda, 1 gallon of hot water, and a good squirt of liquid dish soap. Use a push broom or stiff brush to spread this around and scrub dirty spots. Rinse, and let it dry.
  3. For lingering stains, rewet the surface and sprinkle it with oxygenated bleach. Unlike the chlorinated version, oxygen bleach won’t harm your lawn or any plants lining your driveway. (I use OxiClean.) Again, use the broom’s bristles to scrub the area, then let the oxygenated bleach work for 10-15 minutes.
  4. Rinse the surface and your broom. Let both fully air dry.

Removing Mold, Mildew, or Moss

Sweeping alone isn’t enough to remove mold, moss, or cement from other organic matter. To clean mold stains on your cement, you have to kill the spores or plant material causing the problem.

  1. Spray the moss stain on your cement with equal parts of distilled white vinegar and hot water.
  2. Using the push broom, scrub the area well after spraying.
  3. Rinse with a bucket of fresh water and let the area completely dry.

For really stubborn mold or mildew stains on cement, use a solution of 1/4 cup oxygenated bleach mixed into 1 gallon of hot water. Let this sit in place for 15-30 minutes, then rinse and dry the surface.

Grease or Oil Stains

Oil leaks from cars, lawnmowers, or other equipment can leave a slippery stain on your concrete floor. Since cement is porous, you may find the oily mess has worked its way below the surface to leave a deep stain.

It is possible to get rid of these greasy cement stains, but you’ll need to be patient. In other words, the best way to clean your cement’s grease stains is with a good application of elbow grease. Here’s how.

  1. Soak up the surface spill by sprinkling the area heavily with baby powder, cornstarch, clay cat litter, or diatomaceous earth. (I keep a bag of the latter on hand for cement stains and also to keep ants out of the house.) These substances are all very absorbent and can pull greasy messes out of cement. You need to apply a thick layer, though, of around a half-inch.
  2. Allow the powder to remain in place 24 hours to lift the oil. Check it a few times and apply more powder if you see the top layer starting to show grease. After a full day, sweep up the mess and discard it.
  3. Next, combine 1 quart of very hot water and 1 teaspoon liquid dish soap in a bucket. (Adding 1/4 cup of Pine-Sol can help, but avoid using pine oil products if you have pets.)
  4. Apply the mixture to the area and scrub it with a brush or broom. Rinse well with hot water, then let it air dry.

Removing Rust Stains

If the rust stain on your cement is fairly fresh, cleaning it with straight white vinegar and a stiff brush may be enough to remove it. Rinse well with fresh water afterward, though, since undiluted vinegar can etch cement over time.

For larger or older rust stains, get the area damp and then sprinkle it with a product containing oxalic acid. (I use Bar Keeper’s Friend.) This all-natural acid is mild enough that it won’t etch your cement but strong enough to dissolve rust. Scrub the spot with a stiff brush, rinse thoroughly, and repeat until the stain is gone.

Tips to Prevent Cement Stains

It’s always better to prevent stains than to let them happen and hope you can get rid of them by cleaning. The tips below will help you avoid the most common stains on your cement or concrete surfaces.

Clean concrete walkway bordered by trimmed lawn and hedge

Sealants

Applying a sealant to your garage floor protects it from stains and keeps concrete floors looking brand new. If you plan to sell your home in the next year or two, this step can really impress buyers. (Here are more cleaning tips to protect your home’s value.) DIY sealants need to be reapplied every 2 to 3 years. Professional, penetrating concrete sealants can last as long as 20 years and often carry a transferrable warranty.

Barriers and Liners

Use a removable, waterproof barrier between your cement and things likely to stain it. In the garage, this means lining the floor beneath your cars with oil drip mats. Look for a slip-proof one that’s easy to clean and it will keep oil or other leaking car fluids from damaging your floor. (We use this one.)

Use rugs or mats beneath patio furniture to catch spills and prevent rust spots. Choose a rug specifically designed for outdoor use so water doesn’t damage it. Outdoor rugs and mats won’t trap water beneath them that could lead to mold or mildew growing on your patio.

Don’t put flower pots directly onto your patio or front step. Use drip trays beneath planters so runoff and soil don’t cause stains. Be sure to empty those trays after heavy rains so they don’t attract mosquitoes. (Here are more ways to keep mosquitoes away from your patio.)

Deal with Moisture

Don’t let moisture etch or discolor cement. Use downspout extensions to divert rainwater from your home’s foundation and into the lawn rather than onto your concrete surfaces. Also, make sure to clear away leaves and other debris after storms or during the fall season. Letting autumn leaves collect on your patio can trap moisture and cause mold and mildew stains.

How Often to Clean Cement Areas

Cleaning your outdoor areas is a year-round task. Sweep cement patios, steps, and sidewalks weekly during warm weather and at least once a month during winter. Sweep your garage at least once a month, too. Clean spills on concrete when you see them and use fans to dry indoor cement areas any time they get wet. Routine cleaning of cement and concrete areas is ultimately the easiest way to prevent stains.

5 Comments

  1. James Bergman says:

    I never would have thought of using baby powder to clean up oil stains in my garage. I had heard about cat litter, but it never really did all that much, probably because I didn’t grind it up first. Anyway, thanks for the tip hopefully I can get the oil stains up quickly so that I can reseal the floor.

    1. Here is a tip. If using a push broom with the cat litter, flip it over and grind the litter in with the wooden side of the broom first. It will work great to grind up the litter and force it into the stain.

    2. Katie Berry says:

      That’s a helpful tip, Dale. Thank you for sharing!

  2. I have white cauking smears on my cement door threshold and surrounding brick from a bad installation. How can I remove these stains?

    1. Katie Berry says:

      Hi Gerry,
      Mineral spirits and a good scrub with a stiff brush should do it. You can also find caulk residue removers at most hardware stores.

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