Can power washing damage vinyl siding?

How power washing damages vinyl

Vinyl siding is tough against weather, but it isn’t built to take a concentrated jet of water up close. Most of the damage comes from a few common mistakes.

• Too much pressure. A strong stream can crack a panel, dent it, or leave marks in the surface. Old, brittle siding cracks more easily.
• Spraying upward. Vinyl panels overlap like shingles, top over bottom, so rain runs off. Aim the spray up under those laps and water goes straight behind the siding, where it soaks the house wrap and sheathing and can lead to rot, mold or peeling paint inside.
• Tip too narrow, too close. A pencil-thin spray held a few inches from the wall concentrates all that force on a tiny spot. That’s how panels get scarred or pop loose from their locks.
• Washing in the cold. Vinyl gets stiffer and more brittle in cold weather, so it cracks more easily.

The spots that get hurt most

Siding itself isn’t the only thing at risk. The spray can force water into window frames and past their seals, into dryer vents and bath fan vents, into outdoor outlets and light fixtures, and up into the soffit vents under the roof edge. Those are the places to slow down, lower the pressure, or skip the spray entirely and clean by hand.

What soft washing means

The safer way to clean vinyl is often called a soft wash. Instead of using pressure to knock dirt off, you let a cleaner do the work. The siding gets wet, a cleaner made for siding goes on to loosen dirt and kill the green mildew and algae, it sits for a bit, and then it’s rinsed off with low pressure from the top down. The result is usually cleaner than a high-pressure blast, and the mildew is less likely to come right back, because it was treated instead of just sprayed off.

Old, faded siding needs extra care

Vinyl that has been in the sun for years often gets a chalky film on the surface. Rub your hand on it and it comes away white. That’s oxidation. Washing can take some of it off, but if it comes off unevenly you end up with lighter streaks and patches. A gentle, even wash helps. We’ll also tell you honestly when siding is faded enough that a wash won’t make it look new.

Signs your siding was damaged by washing

• Cracks or small holes in panels, often near the bottom of the wall
• Panels that are loose, bowed or unlocked from the one below
• Streaks or blotches that weren’t there before
• Water stains, peeling paint or a musty smell on the inside of an outside wall
• Moisture or fog inside window glass after a wash
• Outdoor outlets that trip after being sprayed

If you see any of these after a wash, it’s worth having someone take a closer look. Water behind the siding doesn’t always show up right away.

Should you do it yourself?

Plenty of homeowners wash their own siding. If you do, rent or buy a machine with adjustable pressure, use the widest tip, and start with a siding cleaner rather than pressure alone. Stand back from the wall, keep the spray pointed down and along the siding, and work from the top of each section down. Skip the windows, vents and fixtures. And don’t climb a ladder with a pressure washer. The kickback can throw you off balance. For two-story walls, the upper part of a high ranch or a colonial, it’s often worth having it done for you.

How we wash vinyl siding

We walk the house first and look at the condition of the siding, the windows and anything fragile nearby. We cover outlets and fixtures, wet down the plants, and apply a siding cleaner at low pressure. After it has had time to work, we rinse from the top down, keeping the spray aimed down the wall, never up under the laps. If we notice a cracked panel, a loose piece or a spot where water may be getting in, we’ll point it out before we leave. And if the deck, the fence or the walkway need a wash too, we match the method to each one.