Soft washing versus pressure washing
Vinyl siding, painted wood, stucco and asphalt shingles are cleaned with low pressure and a detergent that kills the algae and mildew, then rinsed. High pressure on these surfaces forces water behind siding, strips paint and blasts granules off shingles. Concrete, brick pavers and bare decking can take real pressure and a surface cleaner attachment.
The green and black streaking on north-facing walls and roofs around Clarksville is algae feeding on the humidity. It comes back if the surface is only rinsed, which is why detergent matters.
House washing
A whole-house wash covers siding, soffits, fascia, gutters exteriors, windows and trim. Plants and beds are wetted down before and rinsed after so the detergent does not scorch them. Outlets and light fixtures are covered.
Most homes here benefit from an annual wash, and it is the required first step before any exterior painting.
Roof cleaning
Black streaks on shingles are Gloeocapsa magma, an algae that feeds on the limestone filler in the shingle. It shortens the roof's life by holding moisture and heat. We treat roofs with a low-pressure application and let the solution work rather than scrubbing or blasting, which would wreck the shingles. The streaks fade over the following weeks of rain.
While on the roof we note any lifted shingles or damaged flashing and report them, since a cleaning visit is also a free look at the roof's condition.
Driveways, patios and decks
Concrete and pavers get a surface cleaner that lifts the grime evenly without leaving zebra stripes. Decks are washed at moderate pressure with the grain, then allowed to dry for at least two days before any stain or sealer goes on. Washing a deck too hard raises the wood fibres and ruins the finish.
Before-and-after and timing
Washing before an exterior paint job, before a deck stain, before listing a house for sale or simply before summer cookouts are the common reasons to book. Spring pollen season and the end of autumn leaf drop are the two busiest windows.
What can go wrong with a careless wash
Water forced behind vinyl siding soaks the sheathing and shows up weeks later as mould on an interior wall. Blasting a window seal breaks the glazing and fogs a double-pane unit. Hitting a mortar joint on old brick at high pressure eats the mortar out. Each of these is a common result of a rented machine on a Saturday.
The safe method is lower pressure, the right nozzle, the right detergent and enough dwell time for the chemistry to work. It takes a little longer and leaves nothing to repair.