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What fails on a house, why it fails, and what it should cost

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Siding · You can handle this one

Chalky residue on painted aluminum

That powder is oxidation of the paint, not failing siding. It can be cleaned and repainted rather than replaced, which is a much cheaper path if the panels are sound.

Quick answerChalky residue on aluminum siding is oxidation. Years of sun break down the painted finish, and the surface turns to a fine powder that rubs off on your hand. The metal underneath is usually fine. If the panels are straight and secure, wash them, and repaint if the color has faded too far. You can handle this one yourself. No call needed.

Aluminum siding doesn’t rot, and it rarely wears out. What wears out is the finish. Replacing sound panels because the paint has chalked is paying for new siding when the old siding only needed cleaning and a coat of paint.

1Why aluminum siding chalks

  • Sun exposure. UV light slowly breaks down the binder in the factory paint. South and west walls usually chalk first and worst.
  • Age. Most aluminum siding is decades old now. Some chalking is normal and expected at that age.
  • Weathering. Rain washes chalk down the wall, which is why you may see streaks on brick or foundation below.

2How to check it

  1. Rub the surfaceWipe a dark cloth or your palm across a panel. Color on the cloth is chalk.
  2. Look along each wallCheck that panels lie flat and are locked together. Loose, torn or badly dented panels are a different problem.
  3. Check the jointsLook at caulk where siding meets windows, doors and trim. Open joints matter more than chalk.
  4. Decide on paintIf the color is even after washing, you may only need to clean. If it’s faded or patchy, plan to repaint.

3Fixing it

Do it yourself

  • Wash with water, a mild detergent and a soft brush, working from the bottom up
  • Rinse well from the top down so no residue dries on
  • Use low pressure; high pressure can drive water behind the panels
  • Repaint with a paint labeled for metal siding, following its prep steps

Hire a pro

  • The walls are two stories or over a slope
  • Panels are loose, torn or badly damaged
  • You want the whole house repainted at once

Paint won’t stick well to chalk. Clean until a wiped cloth comes away close to clean, and let the wall dry before painting. Test a small area first.

Older homes and ladders

If your home was built before 1978 and you pay someone to scrape or sand painted surfaces, hire a lead-safe certified firm. Work from a stable ladder, and don’t work at height alone.

4What drives the cost

Washing is mostly your time. Repainting costs depend on wall area, the number of stories, how much trim there is, and how much prep the chalk needs. Either way it’s far cheaper than new siding when the panels are sound.

Siding cost

5Questions

Does chalking mean my siding needs replacing?

No. It means the paint is weathering. Replace panels only if they’re loose, torn or badly damaged.

Can I pressure-wash aluminum siding?

Gently, if at all. A soft brush and a garden hose are safer. High pressure can dent panels and force water behind them.

Will it come back after I clean it?

The paint will keep chalking slowly. A fresh coat of paint resets the clock.

Written by Jaylan Jones. I Like To Exterior Services earns a referral fee when a call connects to a contractor. See our business-model disclosure.