Guide
Concrete cleaning — driveways, walks, and patios
Concrete looks tough, but it's porous. Dirt, algae, oil, and iron all sink in, and each one wants a different approach. Doing it in the wrong order — or with the wrong tool — either wastes the work or leaves visible stripes that stay for years.
Driveways, sidewalks, patios — same material, different jobs
All three are concrete, but the job is different for each. A driveway sees oil drips, tire marks, and heavy pollen mats — it needs a full surface-cleaner pass. A sidewalk is narrower, usually cleaner, and often bordered by mulch or grass that has to be protected from runoff. A patio is entertaining space with grease from grills, sunscreen, drink spills, and sometimes rust from furniture legs.
Paver patios add one more concern: the polymeric or silica sand in the joints. A too-close surface-cleaner pass or a narrow high-PSI tip will blow the sand out of the joints and you'll be re-sanding after the wash. The right approach on pavers is a wider tip, a slightly higher stand-off, and a controlled pass — enough to lift the dirt without disturbing the joint fill.
Oil stains — degreaser first, pressure second
Oil isn't a pressure problem, it's a chemistry problem. Water and force alone don't lift oil out of the pores of the concrete; a degreaser does. The order that actually works:
- Apply a citrus- or alkaline-based degreaser directly to the stain and let it dwell 10–15 minutes.
- Agitate with a stiff nylon brush — this pushes the degreaser into the pores.
- Rinse and follow with a full surface-cleaner pass to blend the cleaned spot into the rest of the concrete.
- For old, deep stains (years of drips in the same spot), expect to lighten the stain significantly but not fully remove it — the iron and hydrocarbons have often permanently discolored the concrete.
Rust stains — oxalic acid, not more pressure
Rust on concrete comes from a few sources: iron in well water (irrigation rings), metal patio furniture, fertilizer with iron, and sometimes rebar bleeding through from below. It looks orange or reddish-brown and household cleaners will not touch it.
The right chemistry is a dilute oxalic-acid based rust remover. Applied to the stain, given a few minutes to work, and rinsed — usually the stain lifts on the first pass. Bleach and pressure alone don't work on rust; they just clean the concrete around the stain and make it more visible.
Algae and the green film on north-facing concrete
That green tint you see on the shaded side of a driveway or on the concrete under a downspout is algae — same organism that grows on siding. It cleans off with a pressure pass, but it grows back within months because the spores stay in the pores of the concrete.
The way to make a wash last is to pre-treat with a diluted soft-wash mix before the surface-cleaner pass. The chemistry kills the algae at the root, and a driveway that would have re-greened in 4–6 months typically holds for 12–18. This is the biggest single difference between a $75 rinse job and a proper concrete cleaning.
Seasonal timing that makes a wash last
Middle Tennessee's weather sets a rhythm for concrete work:
- Spring (March–May) — the primary window. Winter grime, road salt residue, and the first pollen wave lift together. A wash now sets you up for a clean summer.
- Summer — targeted only (a grease spill, an oil leak). Pollen mats can get so thick they act like a sponge for algae — don't wait until fall if you see one.
- Fall (September–October) — the second-best window. Clears summer algae before freeze-thaw. A clean, sealed surface going into winter is what actually extends the life of the concrete.
- Winter — mostly skip. Cleaner chemistry works slowly below 40°F and leftover water can freeze on the surface. Storm cleanup is the exception.
Sealing — helpful sometimes, harmful other times
Sealing concrete after a wash can slow re-staining, but it's not automatic. A penetrating (silicate) sealer is usually a good idea on decorative concrete or a driveway you just cleaned heavily. A film-forming (acrylic) sealer looks glossy for a while but eventually flakes off in strips and traps moisture underneath — I don't recommend it on residential driveways.
If your concrete is old, cracked, and shows efflorescence (white powder), sealing can trap moisture and make the surface flake faster. Get it clean first, watch it for a season, then decide.
Stain removal reference
| Stain | Likely cause | Recommended cleaning | Pro recommended |
|---|---|---|---|
| Oil / grease | Vehicle drips, grill runoff | Degreaser dwell + agitation, then surface-cleaner pass | Yes for old, deep stains |
| Rust | Iron in well water, metal furniture, iron fertilizer, rebar bleed | Oxalic-acid based rust remover, short dwell, rinse | Yes — bleach and pressure alone will not work |
| Algae / green film | Shade + humidity keeping the surface damp | Soft-wash pre-treat, then surface-cleaner pass | Yes — DIY rinse grows back within months |
| Tire marks | Hot tires on driveway | Full surface-cleaner pass (mechanical lift) | Optional — pro is faster and streak-free |
| Red-clay staining | Runoff from bare soil or landscaping | Pre-treatment plus a second surface-cleaner pass | Yes — condition escalation, not a rinse job |
| Efflorescence (white powder) | Moisture pushing salts to the surface | Clean first, watch a season before deciding on sealing | Optional — do not seal old, cracked concrete |
Common questions
Will pressure washing damage my concrete?+
Not at typical residential pressures with a surface cleaner. The surface cleaner keeps the tips a fixed distance off the concrete and spreads the force over a wide circle. Damage comes from waving a bare zero-degree tip inches from the surface, which etches lines that are visible forever.
Why does my driveway look striped after washing?+
Zebra striping happens when someone used a bare wand instead of a surface cleaner, or overlapped passes inconsistently. The strips that are lighter are where the pressure passed twice. It usually blends out over a couple of months as the whole surface re-weathers evenly, or it can be corrected by a follow-up surface-cleaner pass.
How do I stop algae from coming back on my driveway?+
Pre-treat with a soft-wash mix during the wash — that kills the algae at the root instead of just knocking it loose. And keep runoff paths clear: overflowing gutters and downspouts that dump on concrete keep it wet long enough for algae to establish.
Do I need to seal my driveway after a wash?+
Not always. Sealing helps decorative or stamped concrete stay clean. For a standard broom-finish driveway, a good wash on schedule is usually enough. Old, cracked, or flaking concrete should NOT be sealed — sealing traps moisture and speeds the flaking.
Will you clean paver patios and driveways?+
Yes — with a wider tip and controlled stand-off so the polymeric or silica sand in the joints stays put. If a job needs re-sanding after the wash, I'll say so up front so you can plan for it.
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