A year on, under the pines
Twelve months after the cleaning there is no green creeping in from the edges, no black film in the shade, and the color still matches from the street to the house. The only marks are a few pine needles and leaves that had dropped that morning. For a drive that sits under this many trees, that is about as good as concrete gets.
Why it lasted: the mold in the pores
Concrete looks solid, but it is full of tiny pores. Mold, mildew and algae grow on the surface and root down into those pores, which is where the dark color comes back from.
Water alone, even at high pressure, only takes off what is on top. The driveway looks clean when it dries, but the growth is still alive in the pores, and in our humidity it is back in a couple of months. That is the driveway that goes dark again by the next summer.
On this drive we put down a cleaning solution first and gave it time to soak into the pores and kill the mold where it lives. Then the surface cleaner took the dead growth and the film off the whole slab at the same pressure, so it dried one even color instead of showing wand stripes. With nothing left alive in the concrete, there was nothing to grow back from, and that is the difference you can see a year later. No sealer went on afterward.
How long a driveway cleaning lasts
Around the greater Columbia area, a driveway that has been properly cleaned stays clean for up to two years. Where yours lands depends on a few things:
- Sun. A drive in full sun dries fast after every rain and can go the full two years. A drive under trees stays damp longer and sits at the shorter end.
- Rain. A wet year or two brings the growth back sooner. After a dry stretch, the same drive can go longer.
- How it was cleaned. Cleaned with a solution that kills the mold in the pores, you get the year or two. Cleaned with water alone, expect it back in a couple of months.
- What lands on it. Leaves, needles, pollen and runoff, more on those below.
This drive is about as shaded as they come, and it has made a full year still looking like the day we left.
What makes a driveway go dark again
Even a properly treated slab picks up new growth in time, because spores land on it every day. Anything that keeps it damp gives them somewhere to settle. Around Chapin and the rest of the lake, the usual culprits are:
- Shade. Under pines and oaks the slab stays wet for hours after rain or dew, and growth starts there first.
- Leaves and needles left to sit. Wet leaves leave tannin stains, and a mat of needles holds water against the concrete.
- Pollen. Every spring the yellow coat on everything holds moisture and feeds the growth through the summer.
- Water running across it. A downspout that empties onto the drive, or a bed that washes out onto it in storms, keeps one patch wet and dark.
Our Chapin driveway page has more on how drives around the lake hold up.
How to stretch the time between cleanings
- Blow off leaves and pine needles every week or two in the fall, before they sit through a rain.
- Rinse the spring pollen off with a garden hose once it stops falling.
- Point downspouts into the beds or the lawn instead of across the concrete.
- Keep the edges of the beds trimmed and topped up, so straw and soil stay off the drive.
- Trim low branches back where you can. A little more sun means a slab that dries out faster.
If you want it to stay cleaner for longer, concrete can be sealed after the clean. The sealer soaks in rather than sitting on top, and it lasts five to eight years. More on that is on our sealing page.
Ask for a quote
Most quotes come back within 24 hours with no site visit, and you do not need to be home on the day as long as we can reach an outside tap. A lot of people book the driveway and a house wash together, the way this customer has now done both. More about the work we do around the lake is on our Chapin page, and the full rundown on concrete is on our driveway and concrete cleaning page.