Clean a Concrete Garage Floor

Concrete holds everything you drip, track, or spill until you make it let go. Oil darkens it, road salt etches it, and dust settles into the pores until the slab looks older than it is. A clean garage floor changes the whole space — tools look sharper, cars sit better, and walking in barefoot after unloading groceries doesn't feel like a mistake. This is straightforward work with immediate payoff. The concrete itself wants to be clean; you're just giving it the mechanical and chemical help it needs. Done right, this takes a Saturday morning and leaves you with a floor that looks maintained instead of neglected. If you're planning to seal or epoxy later, this cleaning process is the foundation. If you just want a clean garage, it's the whole job.

1. Clear and sweep everything. Move everything off the concrete — cars, storage shelves, toolboxes, bikes. Sweep the entire surface with a push broom to remove loose dirt, leaves, and debris. Get into corners where dust builds up. If there are oil-dry pellets or old cardboard from previous spills, remove those now.
2. Target oil stains aggressively. Spray or pour concrete degreaser directly onto oil stains, transmission fluid spots, and any dark discoloration. Let it sit for 10-15 minutes so the surfactants can break down the petroleum. For old stains, use a putty knife to scrape away the surface layer of contaminated concrete before applying degreaser.
3. Mix hot cleaning solution. In a 5-gallon bucket, mix concrete cleaner according to package directions, or make a TSP solution with 1 cup trisodium phosphate per 2 gallons of hot water. Wear rubber gloves. Hot water opens concrete pores and helps the cleaner penetrate.
4. Scrub in systematic sections. Pour the cleaning solution across the floor in sections, working from back to front. Use a stiff-bristle push broom or deck brush to scrub in overlapping passes. Pay extra attention to tire tracks, oil stains, and the apron where road salt concentrates. The concrete will foam slightly as the cleaner works.
5. Let chemistry do the work. After scrubbing, let the cleaning solution sit on the concrete for 10-15 minutes. Don't let it dry completely. If the floor starts to look dry, mist it lightly with water to keep the cleaner active.
6. Blast away all residue. Starting at the back of the garage, use a pressure washer with a 25-degree nozzle to rinse the floor, pushing water toward the door. Overlap each pass. Continue until runoff water is clear. If you don't have a pressure washer, a garden hose with a high-pressure nozzle works but takes longer.
7. Push water out fast. Use a floor squeegee to push remaining water out the garage door. Open the door fully and run a fan to accelerate drying. Concrete needs 24 hours to dry completely before you move items back or drive on it.
8. Finish stubborn stains. Once dry, inspect for any stains that survived. Treat stubborn oil spots with a poultice made from degreaser and talcum powder, spread it on thick, let it dry for 24 hours, then sweep it up. Rust stains respond to oxalic acid cleaner.