Why Exterior Paint Prep Starts With a Power Wash

Paint sticks to surfaces, not to dirt

Exterior paint is a coating, and a coating is only as good as its grip on whatever's under it. If the wall is covered in dust, chalky residue, mildew or a fine film of oil from the air, the paint grips that layer instead of the siding. When the layer lets go, the paint goes with it, and the peeling that follows gets blamed on the paint.

That's why washing comes first in nearly every exterior painting job. It's not a bonus step to make the house look cleaner for the painter. It's what gives the new coat something solid to hold onto.

What a power wash takes off

A garden hose won't do much against what builds up on a house in a place like southwest Oklahoma. Wind carries fine dust and dirt across the plains and leaves it on every wall. Rain splashes soil up onto the lower courses of siding. Shaded corners grow mildew, and wood decks gather gray, weathered fibers that haven't been protected.

• Dust and dirt that settle on walls, trim and eaves
• Mildew and algae on shaded or damp surfaces
• Chalky, deteriorating paint from the last coat
• Stains on concrete, such as tire marks and oil near the garage
• Loose, flaking paint that will not hold a new coat

Pressure and water do most of the work, and the right amount depends on the surface. Johnson's Painting & Roofing says it uses the latest power washing equipment to remove tough stains from driveways, walls and more, and a good operator adjusts the pressure and tip for what's being cleaned.

Surfaces to wash, and what comes next

Johnson's lists power washing for decks, the entire home, driveways, sidewalks, gutters, siding, blocks and bricks. Each one behaves differently under water, so the approach isn't the same all the way around the property.

• Siding: wash from top to bottom with moderate pressure so water doesn't get driven behind the boards
• Brick and block: these are porous and need gentler handling, and they hold on to moisture longer
• Wood decks: pressure that is too high raises the grain and gouges soft boards, so the setting matters
• Gutters: cleaning out grime now keeps streaks from running down the freshly painted walls later
• Driveways and sidewalks: tougher stains often respond to concrete-safe pressure, and cleaning them makes the entrance look finished

Gutters are an easy one to forget. If they're left dirty, the first heavy rain after the paint job sends black streaks over the new finish. Washing them while the equipment is already out is cheap insurance for the paint.

Washing and scraping work together. Water knocks off the dirt and the loosest paint, and scraping removes whatever is left that won't hold. Johnson's lists scraping alongside power washing in its exterior painting work, which reflects the usual order: clean, remove loose paint, let it dry, then prime and paint.

Doing it in the other order doesn't work as well. Scrape a dirty wall and the debris falls into the cracks you're trying to clean. Wash first, and you can see which areas of paint are really failing, instead of guessing from a dusty surface.

Give the surface time to dry

The gap between washing and painting is where many jobs go wrong. Paint over damp wood or masonry and the moisture has nowhere to go, which can cause bubbles and poor adhesion. As a general rule, the surface should be fully dry before any primer or paint goes on, and that can mean waiting a day or more depending on the weather and the material.

Wood and brick hold moisture longer than painted siding, and shaded walls dry more slowly than ones facing the afternoon sun. Plan the schedule around the weather, and don't let anyone rush it because the crew is available. A short delay costs far less than repainting.

On the other side of the gap, don't wait too long. A wall that has been washed and left for weeks starts collecting dust again. The ideal is a clean, dry surface painted soon after.

What to settle before you book

If you're planning to repaint the outside of your house, a few quick questions will keep the project in order.

• Is power washing part of the painting job, or a separate step?
• Which surfaces will be washed: siding only, or also the deck, driveway and gutters?
• How long will the house be left to dry before priming?
• Who handles scraping and any wood that needs attention?

Ask for a free quote

Johnson's Painting & Roofing offers free quotes on exterior painting and power washing for homes and commercial buildings in Lawton and Duncan. Call (580) 695-9941. The line is open 24 hours, seven days a week, and se habla español. Tell them which surfaces you want cleaned and painted, and ask how the washing and drying will be scheduled.