Concrete cleaning, matched to the slab you actually have

What is concrete cleaning?

Concrete cleaning is mechanical and chemical work on poured slabs - exterior pads, garage floors and utility areas - using a surface cleaner for even results and targeted pre-treatment for oil and rubber. Sound, unsealed concrete can take higher pressure than walls; sealed, stained, polished or already-spalling concrete cannot be treated the same way. The job succeeds when the crew names the finish and the stain chemistry before the machine starts.

Signs you need concrete cleaning

• The garage floor is black at the tyre paths and sticky at the drip line under the engine bay
• A previous "clean" left zebra stripes that show every time the light hits the slab
• You are about to seal, epoxy or coat the floor and contamination will ruin adhesion
• White powdery bloom keeps returning after ordinary washing
• Tyre marks and plasticizer staining from hot summer parking will not mop away
• Outdoor plain concrete steps or a pad are green and dusty but not decorative stone
• You can see wand stripes from a previous clean that look worse in raking light
• A coating contractor has refused to start until the slab is properly prepped

Seeing something not on this list? Browse pressure washing problems by symptom →

How concrete cleaning actually works

1. 1

   Name the finish - bare, sealed, coated or polished

   Bare grey concrete, acrylic sealer, epoxy, stain and polish all set different pressure and chemistry limits. A coat that is failing will lift in sheets if you clean it like raw slab. Naming the finish and stain class up front prevents the classic bright-halo-dark-centre oil failure.

   Watch forOne price for "the concrete" with no finish identified. That is a guess, not a method. Ask for that risk to be named on the walkthrough, not after damage shows.

2. 2

   Separate dirt from chemistry stains

   General soiling lifts with even mechanical cleaning. Oil, rust, tyre plasticizers and efflorescence need pre-treatment or a different product class before any rinse. Naming the finish and stain class up front prevents the classic bright-halo-dark-centre oil failure.

   Watch forMore pressure sold as the answer to oil. Pressure removes paste around the stain and leaves a bright halo with a dark centre. Ask for that risk to be named on the walkthrough, not after damage shows.

3. 3

   Hot water and degreasers where grease lives

   Garage and shop slabs often need heat and alkaline degreasers with dwell time. Cold water at high pressure is a poor substitute for dissolved grease. Naming the finish and stain class up front prevents the classic bright-halo-dark-centre oil failure.

   Watch forA residential wall-wash crew without hot water quoting a machine-shop floor as if it were a patio. Ask for that risk to be named on the walkthrough, not after damage shows.

4. 4

   Surface-clean in controlled passes

   An enclosed spinning surface cleaner keeps distance and dwell consistent so the slab lightens uniformly. Edges and corners are detailed afterward. Naming the finish and stain class up front prevents the classic bright-halo-dark-centre oil failure.

   Watch forOpen-wand work across the main field. Permanent striping is the signature failure of concrete cleaning done cheap. Ask for that risk to be named on the walkthrough, not after damage shows.

5. 5

   Rinse, dry path and coating readiness

   Residue is rinsed out of pores and joints. If a coating follows, moisture and pH readiness are separate from "looks clean when wet." Naming the finish and stain class up front prevents the classic bright-halo-dark-centre oil failure.

   Watch forSame-day epoxy over a damp, high-pH slab. Bond failure shows up months later as peeling islands. Ask for that risk to be named on the walkthrough, not after damage shows.

What does concrete cleaning cost?

Concrete cleaning is typically priced by area and condition, with garage oil work, hot water and heavy degreasing as adders. Coating prep is a different scope than a cosmetic wash. The Cost Guide covers how exterior and hard-surface cleaning quotes stack.

See the full concrete cleaning cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →