Q: The aluminum siding on my house has growths on it and the paint seems to be rubbing off. Other than these problems, the siding is in good shape. What can I do to make things look better? Some people tell me new siding is the best option.

A: Painting is the easiest and most economical option for renewing the look of tired aluminum siding. There are three reasons I recommend against siding replacement in favour of repainting in your case:

1. Painting is much less expensive than replacing all that metal with vinyl.
2. The physical durability of aluminum is better than vinyl. Aluminum is simply a much better product in several ways.
3. Sprucing up the aluminum also saves lots of resources, so it’s good for the environment.

New paint applied to aluminum siding can last a long time as long as you address a few unique details. Begin by washing the surface in the same way you’d tackle the outside of your car, but with a little more vigour. Scrub with warm, soapy water and a brush. Don’t use a pressure washer.  Rinse well to remove dirt, soap residue and oxidized paint. You might be tempted to use a pressure washer here, but that’s not a great idea. It’s all too easy for water to be forced up underneath the siding and into window trim. And besides, scrubbing with a brush removes dirt, chalky old paint and mold better than a pressure washer ever can. Don’t settle for anything remaining on the old siding. It needs to be perfectly clean with all loose stuff removed before proceeding. Let the siding dry for a couple of good days, then get ready to paint.

The key to successful painting of aluminum siding is oil-base primer. As good as latex primers are these days, don’t use them in this situation because chemicals in the mix will react badly with the aluminum. That said, the paint itself should be the highest grade of 100% acrylic exterior latex you can find. Let the oil-based primer dry for a week (don’t rush on this timeline because you need full and complete drying), then apply two coats of latex paint. A flat or low-sheen formulation looks best on siding because it doesn’t show imperfections like high-gloss paints do. For best possible results, consider spray application. If that’s a problem, experiment with rollers. You’ll get faster coverage than with a brush and a more even result. One excellent option involves brushing on the paint so you can get into all nooks and crannies, then immediately roll out the paint in that area with a paint roller to create an even texture that’s free of brush strokes. I know professionals who paint the entire outside of multi-story buildings like this and they do it faster than spraying because no masking is required.

Got vinyl siding that needs some color? The same approach applies to vinyl, except you should use a primer and paint made especially for this job. Ask at any specialty paint store for recommendations on primer and paint for vinyl siding.