Most of what is on your driveway is alive.

What is actually on the concrete

The black on a Pinellas driveway is not dirt. It is algae living in the surface of the concrete, which is why a garden hose and a brush do nothing to it. The green film on a shaded walkway and the black speckle on the north wall are the same thing in a different spot.

Then there is everything else. Rust from well water sprinklers, tannin stains under an oak, oil where the car parks, a gray film of grit along the street edge. Each one comes off, and each one comes off differently. Pressure alone is the wrong tool for most of it.

So a wash starts with the right cleaner on the surface, given time to kill the growth and loosen the stain, and then the pressure carries it off. That order is why the concrete stays clean longer than a slab that was simply blasted.

• Cleaner applied and given time before any pressure
• Surface cleaner across the full slab, no wand stripes
• Low pressure soft wash on stucco, siding and soffit
• Plants soaked before and rinsed after
• Everything flushed to the street when we are done

The surface cleaner and the stripes it prevents

A wand pushes all the water through one narrow jet. Swept across a driveway it leaves arcs, and once you have seen them in low evening light you cannot stop seeing them. They stay for years because the wand cut the concrete unevenly.

A surface cleaner is a round hood with jets on a spinning bar. It covers the full width at one even pressure and walks the slab like a mower walks a lawn, so the driveway reads as one clean surface instead of a record of where somebody swung their arm.

Edges, steps and the strip along the garage still get a wand, on purpose and with care. The field gets cleaned evenly and the edges get cut in. It is the same discipline as painting a wall.

House washing, and the pressure that ruins stucco

A house wash is a different job from a driveway. Walls get low pressure and a cleaner, because that is the only safe way to take mildew off stucco, painted block or vinyl. High pressure forces water in behind the finish, chews texture off the stucco, and can push water past a window frame into the wall.

This is also the step that decides how long a paint job lasts. Chalk and mildew left on a wall become the layer the new paint is stuck to, and paint on loose chalk lets go early. When a wash is the first stage of a repaint, we clean it knowing something is going on top.

Soffit, fascia and the face of the gutters get done at the same time. Those are the parts people forget, and they are the parts that leave a clean house looking half done when they are skipped.

Roofs, pool decks and lanai cages

Tile and shingle roofs in this county go black with algae on the north slope. A roof gets a soft wash, cleaner at low pressure, because high pressure lifts shingles and cracks tile. If a roof coating is coming later, the wash is the first step of that job too.

Pool decks are usually the dirtiest surface on a lot and the one people most want back. Textured deck coatings and pavers hold algae in the low spots, so they want cleaner and even pressure. Push too hard on a paver and you strip the face and leave it looking chewed. Paver joints lose sand in a wash, and re-sanding is part of doing it right.

Lanai cages collect a green film on the screen and the frame. They get a gentle wash so the screen is not torn, and the aluminum frame comes back bright. Around the pool we plan where the runoff goes first, because cleaner in the pool is somebody's afternoon gone.

Washing on its own, or before paint

When a wash is the first step of an exterior repaint, it is priced inside the paint job. Same work, higher standard, because the wall has to be clean enough to bond and dry enough to coat.

A lot of the washing we do has no paint after it. Sometimes the paint on a house is fine and it is the algae and grime making the place look tired. We would rather say that and wash it than sell a repaint you do not need for years.

Landlords call for this between tenants. Matthew Hill wrote that we painted "a couple rental properties" for him, and a wash on the drive and the walls is often what gets a rental listing photo looking right without a full repaint.