White Exterior Paint: How to Keep a White House Looking White

To keep a white house looking white, start with a quality exterior finish that resists chalking and mildew, pick a white that suits the light on your street, and wash the siding gently about once a year. Most dingy white houses in St. Louis and Webster Groves aren't permanently stained. They're dirty, chalking or growing mildew.

Each of those has its own look and its own fix, which is why scrubbing harder rarely solves it. Midsummer is when people notice. The humidity's up, the spring pollen has settled into every lap of siding, and the north side of the house is starting to look a little green.

Why does white exterior paint turn gray or dingy?

Usually it's chalk, dirt or mildew. Sometimes all three on the same wall.

• Chalking is the paint itself breaking down. UV attacks the binder, and loose pigment comes off as a fine powder. Rub the siding with a dark cloth. If it comes away white, that's chalk.
• Dirt pickup is grime sticking to the surface: road dust, pollen, soot, and those gray streaks under window sills and gutters. Softer, flatter finishes tend to hang onto it.
• Mildew shows up as gray, black or greenish speckles, usually on shaded walls, behind shrubs and up under the eaves. Dab a spot with diluted bleach. Mildew lightens within a minute or two. Dirt doesn't.

Chalk on white paint is sneaky, because white powder on a white wall looks fine from the street. The trouble shows up below it. You get white streaks running down over a red brick foundation, and the siding looks flat and tired up close. It matters before any repaint, too, since new paint brushed over chalk doesn't bond well and can peel.

Should you pick a bright white or a softer off-white?

For most houses, a white with a little warmth or gray in it looks clean longer than a stark bright white. It hides light dust better and doesn't glare in full afternoon sun.

Bright whites look crisp on a paint chip and on a narrow trim board. Spread across a whole two-story elevation in July sun, they can be blinding, and every bit of dirt reads as a smudge. Warm whites with a hint of cream sit nicely next to St. Louis red brick and limestone. Cool whites with a touch of gray suit farmhouse styles and dark roofs. A true off-white or very pale greige sits in between, and it's the most forgiving of the bunch.

Here's a habit worth copying. Paint large samples on the actual wall and look at them at noon and again in late afternoon. Indoors under bulbs, whites all look alike. Outside, the differences jump out at you. And if you're torn between white and a light color, our post on exterior paint fading and which colors last longest explains why lighter shades tend to hold up better in the sun.

Color is personal, but neighbors notice when it's right. One homeowner told us:

That's what a well-chosen white does. It makes the trim, the brick and the landscaping look intentional instead of washed out.

How do you clean white siding without damaging it?

Soft-wash it. Low pressure, a siding-safe cleaner and a top-down rinse will lift dirt and mildew without stripping paint or forcing water behind the boards.

1. Close the windows, cover delicate plants, and wet the shrubs down first.
2. Apply a cleaner made for exterior siding, working from the bottom up so it doesn't streak.
3. Let it sit a few minutes, but don't let it dry. Do the sunny walls early in the morning.
4. Rinse from the top down with a garden hose, or a pressure washer on a wide, low-pressure tip held well back.
5. Spot-treat any remaining mildew with a mildewcide cleaner and rinse again.

Skip the narrow pencil tip. High pressure can etch paint, gouge soft wood and drive water up behind lap siding, which leads to exactly the peeling you're trying to avoid. On older homes that may have lead paint under the newer layers, be extra gentle and don't blast anything loose.

How often should a white house be washed?

Once a year works for most homes, with a quick spot-clean on the north side and under the gutters in between. Heavily shaded lots or houses near a busy road may need it more often.

The cheap prevention matters just as much. Keep gutters clear so they don't overflow down the siding. Trim shrubs back from the walls so air can move. Aim sprinklers away from the house. Those habits do more to keep white paint clean than any product on a store shelf.

What exterior finish keeps white looking white longest?

One that resists chalking and mildew and holds its color under UV. With conventional paint, that means a quality acrylic exterior product over a clean, sound surface. With a coating system, it means a much thicker film built for long exposure.

Traditional exterior paint goes on at roughly 1 to 2 mils, and most homeowners end up repainting every 5 to 7 years. Rhino Shield's ceramic elastomeric coating is built to 8 to 10 mils over a full prep sequence: cleaning, repairs, caulking and sealing, primer, then multiple topcoats. The ceramic microspheres help reflect UV, and the coating is formulated to resist mold, mildew and fading. You'll still want to rinse it now and then, because nothing stays spotless through a Missouri summer, but you can stop repainting every 5 to 7 years. Our exterior paint coatings page walks through how the system goes on and what the 25-year transferable warranty covers.

Whatever you use, buy on performance rather than the label's promises. The Master Painters Institute publishes performance standards and approved product lists for exterior coatings, which is a more reliable guide than the marketing on the can. Rhino Shield of Missouri crews work as exterior painters across the St. Louis area, and we're happy to tell you honestly whether your house needs a coating or just a good wash.

Frequently Asked Questions

Why is my white house turning green?

It's almost always algae or mildew, and it shows up on shaded or north-facing walls where moisture lingers. Missouri's summer humidity feeds it. A siding cleaner with mildewcide and a gentle rinse will remove it, and trimming plants back for airflow helps keep it from coming back.

Does white exterior paint show dirt more than other colors?

It shows dark grime more, especially in a flat finish. White hides chalk, dust and fading better than dark colors, though. A soft off-white is a good compromise if you want a white house that stays clean-looking between washes.

Can you pressure wash white painted siding?

Yes, carefully. Use a wide, low-pressure tip, keep the wand well back, and spray downward so water doesn't get pushed up behind the laps. A cleaner does most of the work, so the water only needs to rinse.

What sheen is best for white exterior paint?

Satin or low-luster is a common pick for siding because it sheds dirt better than flat while still hiding small surface flaws. Semi-gloss is typical on trim and doors. Flat finishes look soft but tend to hold onto grime.

Thinking about a white exterior?

We can look at your siding, tell you whether that gray film is chalk, dirt or mildew, and talk through whites that suit your house. Request an estimate or call 314-239-7947, Monday through Friday 8 a.m. to 6 p.m. and Saturday 10 a.m. to 2 p.m.