Savannah decks and patios grow a green film because of what the city is
The short version of why your deck or patio looks slick a few weeks after every storm is that Savannah sits in the Lowcountry, and the Lowcountry is a greenhouse. The live oaks that make downtown and the islands so shaded hold the damp on the north side of every house for most of the day, the river and the marsh keep the air humid almost year-round, and the spring pollen coats horizontal surfaces in a layer that holds the next round of moisture against the wood. That combination - shade, humidity, and a surface that stays wet - is exactly what mildew, mold, and algae need. It is not that your deck is bad or that you are neglecting it; it is that the climate is working against every horizontal board and paver you own faster than it would almost anywhere else in the country.
The practical consequence is that a Savannah deck is not a once-a-year surface. The shaded corners, the joints between boards, the underside of a stair tread, and the paver seams that stay damp longest are where the film starts, and it spreads from there. That is why we clean these surfaces on a schedule tied to the weather rather than to a calendar: a clean headed into the humid months, and again if the summer storms were heavy.
Downtown heart-pine, island cedar, and composite out in the new subdivisions are three different jobs
The material matters more than the service name. A downtown Savannah veranda is frequently original longleaf heart-pine, a dense, resin-rich wood that shrugs off decay but furrs and splinters if you hit it with pressure meant for concrete. A newer island or marsh-front deck is more likely cedar or a treated softwood that greys within a season of salt air. And the newer composite and capped-polymer decking out toward Pooler, Richmond Hill, and the Southside does not rot at all but still grows a dull film of pollen, algae, and road grime - and it scars if you scrub it with a wire brush or run a wand too hot. We do not have one setting for "deck." We read the board, match the solution and the pressure to it, and adjust the dwell time so the growth lifts without the wood grain fuzzing up or the composite surface scuffing.
Patios and paver surfaces are a joint problem, not just a face problem
With wood the growth sits on the board. With a Savannah paver patio, walkway, or courtyard the trouble lives in the seams. The joint sand between the pavers washes out in our heavy afternoon downpours, and once the sand is gone the joint becomes a damp channel where moss, weeds, and algae root and hold moisture against the stone on both sides. Cleaning the face of a paver while leaving the joints full of growth does not fix the patio - the growth just recolonizes from the seam. That is why the honest order is clean the face, clear and replace the joint material where it has washed out, and only then talk about whether sealing makes sense. If you skip the joint work, you are paying to look at the same patio again within the season.
Cleaning removes the film. It does not restore colour, and knowing which you need saves you money
Most of what a Savannah deck owner is actually disappointed by is grey wood, and grey wood is not dirt sitting on the board - it is sun damage at the surface. Ultraviolet light breaks down the lignin in the wood, and no solution or pressure will put that colour back. Cleaning strips away the green growth and the pollen film and leaves the board pale and dry-toned; it does not return it to its original hue. If your goal is the grey gone, the honest answer is that a wash is the preparation step for a refinishing pass - brightening, and then sealing or staining once the wood has dried on a genuinely dry stretch of weather - and we will tell you which you actually need rather than sell you a wash expecting it to do a restorer's job.
It matters for the other direction too. A composite deck never greyed out in the first place, so treating it like weathered wood and sanding or stripping it would only scratch a surface that cannot be sanded back. For composite, a clean with the right solution and a soft method is the whole job, and the finish is already sealed by the manufacturer. The method has to match what the surface actually is, and that is the part that changes job to job here.
What we protect while we work, and why the method matters more than the pressure
Horizontal cleaning takes the water, the solution, and the rinse somewhere, and on a Savannah lot that somewhere is usually landscaping. The drip line, the beds along a courtyard wall, the young plantings by a newer patio, and the screens and thresholds around a porch all sit right where the runoff goes. We pre-wet beds before any solution is mixed, keep the rinse directed and diluted, and keep the wand off joint sand, screen splines, and the soft boards around a stair. If you are on the islands or marsh side, the same rinse water drains toward the marsh, so we keep solution use measured rather than heavy. None of that is dramatic, and all of it is why the job takes a little longer than a pressure blast and comes out better for it.
If you are not sure whether your deck needs a clean, a clean plus joint work, or the full refinish, the cheap way to find out is a look at what is actually on the surface. Green and black film is growth - a clean fixes it. A grey, dry, silvery tone is sun damage - that is the refinish conversation. A bright face with a loose, weedy joint is a seam problem. Send us a photo of the surface and the edge of a paver, and we will tell you which of the three you are really looking at before you book anything.
