Georgia gives outdoor surfaces a harder time than most of the country, and it does it two different ways at once.
The first is red clay. Our soil stains, and it isn't just sitting on the surface — clay particles are fine enough to work into the pores of concrete, which is why a garden hose moves the loose material and leaves an orange cast behind. That takes pressure and the right detergent to actually pull out.
The second is biological. The dark green-to-black film that builds up on the shaded side of a driveway, on north-facing siding, and along the low edge of a patio is algae and mildew — living organisms fed by our humidity and shade. It's not dirt, and this matters for how it gets treated. Blasting it off with pressure alone removes what you can see and leaves the roots in the pores of the concrete, which is why it comes back within a few months. Treating it first with the right solution kills the organism, and then the wash removes it properly. That's the difference between a wash that lasts a season and one that lasts a couple of years.
There's a safety angle too. Algae on concrete gets genuinely slick when it's wet, and pool surrounds, walkways, and front steps are exactly where you don't want that.
The technique matters as much as the timing. Concrete should be cleaned with a flat surface cleaner — a spinning bar under a shroud that covers a wide path at consistent distance and pressure. Cleaning a driveway with a plain wand instead is how you get those wavy stripes where the passes overlapped, and once they're etched into the concrete they're permanent. Different surfaces also take different pressure: what's right for a concrete driveway will tear up wood decking or force water behind siding, so pressure gets matched to the material every time.
Timing-wise, spring and early fall are ideal — you're washing off what winter or summer built up, and surfaces dry at a reasonable rate. That said, our season is long and we wash year-round. Most homes do well on an annual schedule; shaded properties and anything under trees often want it twice a year.
One last note for anyone thinking about renting a machine: the pressure that cleans concrete will strip paint, gouge wood, break window seals, and drive water behind siding where you can't see it drying. The surface you're standing on is usually forgiving. The wall behind you often isn't.
Call Mr. Brush at (404) 503-6288 for a free estimate on your driveway, patio, or exterior.