No matter what the exterior is, sooner or later, every building needs to be cleaned. That’s preferable to painting—and a lot less expensive—don’t you think?

Metal buildings tend to be far more maintenance-free than other structures, and an exterior that’s impervious to weather and moisture certainly helps. But like your car, you’ll want to give it a wash-down from time to time to keep up appearances – no different to any structure over time. Here’s what you need to know.

Start with Clearing the Perimeter

You’re going to use a pressure washer for this job, so it’s in your best interests to remove everything around the perimeter of the building that might get in the way. You’ll want to keep your attention on the building, and not where you’re walking.

If you haven’t got a pressure washer, they can be rented from just about any home improvement or hardware store. Most of these retail outlets will let you have it for the day. It’s worth the rental fee if you don’ have one.


Even though there are special coatings on most metal buildings that are applied so that the metal is protected and stands up to the elements, you don’t want to use anything too strong or abrasive for this cleaning job. Keep in mind that most of the dirt will be removed with the pressure washer.

Use a phosphate-free detergent for this purpose. Just head to the laundry room and grab what you use to wash your clothes. You’ll want about a quarter of a cup of detergent for every gallon of water you use for cleaning.

Set the power washer on its lower pressure setting. Yes, it’s metal and made to stand up to whatever Mother Nature dishes out—but you’re just doing a pre-wash. Keep the pressure washer’s nozzle low and about 3 feet away from the building walls, and thoroughly coat the exterior metal surfaces with a single coat of the water and detergent mixture.

Start at the top of the structure so that the cleaning mixture runs down to the bottom of the panels. The low pressure and detergent should be enough to begin to loosen everything that’s on the exterior. Be prepared, though to apply a second coat or even bring out a brush for heavily soiled areas.

It’s time to switch to water only for a thorough rinse. Your goal is to leave no trace of the detergent on the metal surface. Mother Nature will take it from there. The day’s sunshine and wind will dry the metal, and you should see a difference.

Keep in Mind

It’s likely that you’ve got things in the surrounding area to watch out for. If you’ve had the building for a few years, you may have plantings around it. The mild laundry detergent you’re using shouldn’t bother most plants – but do your research if your unsure. Cover up any that you know to be extremely delicate. Thoroughly water the rest before you wash your building so that the soil and these plants don’t retain any of the soap.

You may be tempted to let the pressure washer do it all, but it’s a wise idea to go easy around doors and windows. Take a break and check the interior around a freshly washed window or door area. Do the rest by hand if you notice any leaks.

One of the advantages of a metal exterior is that you seldom have to do much to it—other than an occasional wash-down. That’s pretty much all it takes to bring back the beautiful luster of the color. Miracle Truss® offers you 17 different colors for siding, trim, and roofing.

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