Concrete looks tough, but it's actually porous — every drop of oil, leaf tannin and mildew spore soaks in and stays. A surface rinse won't touch most of it. Here's what's really going on.
Common driveway stains and what causes them
- Dark edges and shaded areas: mildew and algae from moisture.
- Black tire scuffs: heat-transferred rubber polymers.
- Brown/orange stains: rust from sprinklers, fertilizer or metal furniture.
- Dark drips under cars: oil and transmission fluid.
- Leaf prints: tannin staining from wet leaves left too long.
Why a regular pressure washer falls short
Waving a wand around leaves visible streaks and "zebra stripes." Pros use a surface cleaner — a spinning bar attachment that delivers even pressure across the whole slab for a uniform clean.
The professional process
- Pre-treat with a degreaser and mildewcide
- Surface-clean the entire slab at consistent pressure
- Spot-treat stubborn stains
- Rinse and (optionally) post-treat to slow regrowth
Should you seal afterward?
Sealing is optional but worth considering on newer driveways — it keeps stains from soaking in and makes future cleanings dramatically easier.
— The Louisville Housewash Crew
