Vinyl and aluminum siding dull for ordinary reasons. Dust, pollen, and road film settle on the wall. Shade and moisture leave a green or grey cast, especially on the north side and behind shrubs. Aluminum can look chalky as the finish weathers. None of that means the wall has to be stripped or replaced. A proper wash is meant to bring both vinyl and aluminum back toward the shine it had when it was new.
The wash used on siding here is a pure water treatment, the same idea as the glass: filter the water, clean the surface, and do not leave a chemical film for the next layer of dirt to stick to. Vinyl and aluminum siding are both in that work. The equipment is set up to rinse the wall without grinding the finish. You should not see a patchy result where one elevation was scrubbed harder than the next.
What you should not do is treat the wall like a driveway. A pressure washer with the wrong tip, held too close, can force water behind vinyl panels, crack a brittle panel, or mark aluminum. That is a different service, for different materials. Pressure washing is for the hard surfaces around the house: concrete, asphalt, interlock, brick, stone, tile, decking, and patios. The siding is washed so the finish stays intact. If someone offers to “blast” the wall the same way they blast a patio, ask which surface they actually mean.
Before a siding wash, walk the wall. Note loose panels, open gaps at the corners, and any place water already gets behind the cladding. A wash will not repair those. It will show them more clearly once the dirt is gone, which is useful, but it is not a fix for damaged pieces. Move what is leaning on the wall: bins, ladders, stacked wood, and hoses. The crew needs the face of the siding, not a maze of objects.
What the wall looks like afterward
A successful wash looks even. The colour should match from the foundation to the soffit, without stripes where a rinse dried and without a dull band under the eaves. Chalky aluminum should look more like itself and less like a white dust. Green shading on vinyl, where it was biological growth rather than a stain in the plastic, should be reduced. Deep stains that have sat for years, or colour that has faded in the sun, will not return to a brand-new panel. The goal is a clean wall, not a repaint.
The glass next to that wall is usually dirty for the same reasons. Pollen and road film do not stop at the corner board. If the siding is being washed because the whole house looks tired, the windows are part of that picture. Timing them in the same season keeps you from washing the wall and then noticing the panes. How often the outside of the house needs a wash is mostly a question of trees, traffic, and which side faces the weather. The siding on the road side and the shady side will ask for attention before the sheltered side does.
After the wash
Once the wall is clean, keep soil and mulch from sitting against the bottom course. Constant damp at the base is how the lower panels stay green. Trim shrubs that lie on the siding. They hold moisture and drop debris straight onto the finish you just had cleaned. A rinse from a garden hose will not replace a filtered wash, but it will keep loose dust from baking on if you catch it early in a dry week.
If the house is being prepared for photos or for a listing, clean siding changes the first impression more than most indoor details, because it is what people see before they reach the door. Book it when the wall actually looks dull, not on a fixed month that ignores whether the house faces a dusty road or a quiet yard.