How to Clean Concrete Floors and Driveways
Cleaning concrete surfaces starts with a mild detergent, then you can up the ante as needed.
The first thing to know about cleaning concrete? You don’t need to go easy on it. After all, it’s one of the most durable building materials used in modern construction. But with its durability comes a stubborn resistance to cleaning, which means that sprucing it up requires some background knowledge, a little homework, and a healthy helping of elbow grease.
Working Time: 1 to 3 hours
Total Time: 1 to 3 hours
Skill Level: Beginner
Estimated Cost: $0 to $25
Before You Begin
Before attempting to remove concrete stains, gather up all of your supplies so you have them at the ready. If you’re using acidic cleaning agents, make sure to wear goggles, gloves, and protective clothing.
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This is an exhaustive list of all of the supplies listed for all of the steps below. You may not need them all—the supplies you actually end up using will depend on the cleaning approach that’s best for your situation.
– Garden hose
– Broom or leaf blower
– Commercial concrete cleaner or trisodium phosphate (TSP)
– Stiffbristled brush
– Pressure washer
– Pressure washer solution for driveways
– Muriatic acid
– Bucket or spray bottle
Cleaning Concrete: Finish the Job in 6 Steps
As you’ll see below, the act of cleaning is just a small part of this task. As is the case with many other DIYs, you need to do diligent research and prep work before picking up a scrub brush.
STEP 1: Determine the type of sealer the concrete has.
Before you can clean concrete, determine what type of sealer was applied, if any, since it can affect the appropriate cleaning methods. If a sealer wasn’t used, stick with a mild detergent or a solution of trisodium phosphate (TSP). Avoid acids since they can damage unsealed concrete.
Some sealers can withstand acidic cleaning agents, but no matter the finish, it’s always best to start with a mild detergent, reserving any acidic cleaners for particularly stubborn stains. Some common sealers and their appropriate cleaning methods include:
- Penetrating sealers: These sealers deeply penetrate concrete to protect it from water damage and deicing agents. They don’t change the concrete’s appearance. Only use a mild cleaning agent as opposed to harsh acids, which can damage this finish.
- Acrylic sealers: Acrylic sealers provide a high-gloss appearance while protecting the concrete from water and deicing damage. The protective film they form is relatively durable, so you can safely use a stiff-bristled brush to scrub away stains. It’s best to stick with a mild detergent as opposed to acidic cleaners, unless absolutely necessary.
- Epoxy coatings: Like acrylic sealers, epoxy coatings provide a high-gloss finish, but they’re harder and more durable, so they can usually withstand the use of acidic cleaning agents, if needed. You can use a stiff-bristled brush to tackle tougher stains.
- Polyurethane sealers: Polyurethane sealers are similar to epoxy coatings, providing a durable, high-gloss finish. Their durability means that you can use acidic cleaning agents, if necessary, as well as a stiff-bristled brush.
Pro tip: It’s not always easy to determine the type of concrete sealer used, especially when the concrete has weathered. If you can’t figure out what was used, don’t start cleaning with harsh chemicals like muriatic acid. Instead, start with something a bit milder.
STEP 2: Prepare the concrete to be cleaned.
The approach you use to prepare and clean concrete can depend on whether the concrete is outside or inside. But either way, you should prepare the area before you start, just as you would if you were painting a concrete floor.
- Indoor cleaning projects: Learning how to clean concrete floors isn’t tricky. To start, remove any furniture, tools, housewares, and other items from the concrete surface. You’ll be using cleaning solutions, so remove anything that might not be able to stand up to detergents.
- Outdoor cleaning projects: Similarly, if you’re wondering how to clean a concrete patio, or another outdoor surface, start by sweeping the surface clean with a broom or use a leaf blower to remove dirt, grit, and gravel. If you’re working around plants and grass, be sure to soak them well with a garden hose prior to cleaning the concrete, as this will prevent the cleaning solution from penetrating the roots.
STEP 3: Treat stains with a mild detergent or TSP.
Apply a mild detergent directly to tough stains and scrub with a stiff-bristled brush. In some cases, this is all you need to do. But if the stains won’t budge, you may need to scrub the area with TSP and then rinse with the hose to lift the stains.
STEP 4: Use a pressure washer to clean outdoor concrete.
If you still have stains after completing step three, try using a pressure washer. Pressure washers can penetrate concrete pores and wash out the dirt and grease. Fill the pressure washer soap reservoir with driveway and concrete cleaner, then apply it to the entire surface using a pressure setting of around 3,000 psi. Then rinse it with water.
STEP 5: Use muriatic acid as a last resort (optional).
You must be extremely cautious with muriatic acid. Don’t use this powerful acid unless you absolutely need to. If you do use it, wear protective gloves, goggles, and clothing, and always follow the manufacturer’s directions for dilution.
As a last resort, apply muriatic acid. Muriatic acid can work wonders on filthy concrete. However, it shouldn’t be used on penetrating sealers since it can damage these finishes. It might also damage some acrylic sealers, so test a small area if you’re not sure.
Start by mixing a solution of 1 part muriatic acid to 10 parts water in a bucket or spray bottle, then soak the stained area. Wait about 10 minutes and then spray the area with a solution of 1 cup of ammonia to 1 gallon of water to neutralize and clean the acid.
Step 6: Apply a concrete sealer or masonry primer and top coat to prevent stains.
Concrete sealers can prevent stains in the future. Consider a clear silane- or siloxane-based water-repellent sealer like Rainguard Micro-Seal Penetrating Concrete Sealer, a favorite from our researched guide to the best concrete sealers. If you prefer a wet look, Foundation Armor’s AR350 Wet Look Sealer is a good choice. You can apply most sealers using a paint roller or sprayer. You can also acid stain the concrete surface before sealing for a marbled look.
If you’re working on indoor concrete and the damage is so extensive that no amount or intensity of cleaning is working, consider applying a masonry primer and top coat to hide old stains and prevent further staining.
We reviewed the basics on cleaning concrete, but here are some answers to lingering questions you might have.
Q. How do you clean rust stains on concrete?
The best way to clean concrete stains depends on the stain. For instance, vinegar is useful for removing rust stains. Simply pour diluted vinegar on the stain and allow it to soak in for 15 to 20 minutes before scrubbing with a stiff brush. Rinse the area afterward.
Q. How do you clean oil off concrete?
If the oil is still wet, you can sprinkle kitty litter or cornstarch over the affected area to soak it up. Let it sit for three days, then vacuum it. To clean dry oil stains, apply a concrete degreaser to the stain, let it sit for several minutes (or according to the manufacturer’s instructions), then rinse it with water. You can also use this method for tire marks.
Q. How do you clean mildew off concrete?
Start by mixing 1 cup of vinegar and 2/3 cup of water in a spray bottle, then apply the solution to the affected area. Let it sit for a few minutes before scrubbing it with a brush and rinsing. If any mildew remains, you can mix 1 cup of bleach with 1 gallon of water, then soak the area and let it sit for several minutes. Scrub the stain with a stiff-bristled brush then rinse with clean water and repeat until all mildew is gone.
Q. How do you clean bird poop off concrete?
Mix 1 tablespoon of detergent with 1 tablespoon of white vinegar and 2 cups of water. Soak the area with the solution, let it sit for 15 minutes, and scrub it clean with a brush. Rinse the area with clean water when finished.