Pressure Washing Vinyl Siding

The damage you cannot see

Vinyl siding is a rain screen. The panels overlap so water runs down the outside, and the wall behind stays dry. Point a pressure washer upward into those overlaps and you defeat the entire design: water goes up under the lap, past the panel, and into the wall cavity where it sits against sheathing and insulation. Nothing looks wrong from outside. The problem shows up later as mould behind the wall or a soft patch of sheathing, and by then the cause is long forgotten.

Cracked and chalked panels are the visible version of the same mistake. Older vinyl becomes brittle with UV exposure, and a close jet can crack it or drive the panel off its nailing hem.

Soft washing is the correct method

Vinyl gets dirty from organic growth, which is a chemical problem rather than a physical one. Green film and grey streaking are algae and mildew rooted in the surface. A cleaning solution kills that growth at the root and rinses away with very little pressure, which is why soft washing gives a longer-lasting result than blasting: force removes what is visible, the solution removes what regrows.

The working method is straightforward. Apply the solution low to high so it does not run down dry siding and streak, give it dwell time without letting it dry, then rinse top to bottom at low pressure with the spray angled downward, following the direction water naturally runs.

Before you start

Close every window and check the ones that do not seal well. Cover exterior outlets and light fixtures. Wet down plants beforehand and rinse them again afterwards, because a cleaning solution left concentrated on foliage is what kills shrubs along a wall. Check for existing gaps around trim, utility penetrations, and dryer vents, since those are entry points that will let water in regardless of technique.

Streaking and why it happens

Dark vertical streaks below gutter joints are usually oxidised aluminium and dirt washing off the gutter itself, not siding staining. Cleaning the siding without cleaning the gutters means the streaks return with the next rain. Chalky white residue on your hand when you touch the wall is oxidised vinyl, which is UV degradation of the panel surface rather than dirt. Cleaning improves it but will not restore the finish.

How often

Once a year suits most houses in this climate, and the shaded elevation usually needs it before the sunny one. North-facing walls and anything under tree cover hold moisture longest and grow back first.

Having it washed

We soft wash siding rather than pressure it, and we handle the gutter exteriors in the same visit so the streaks do not come straight back. Call (504) 688-3995 for a free written estimate.