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Cleaning Aluminum Siding

How to wash away decades of dirt, grime, and mildew

guys on stairs

We purchased a mid 1980s aluminum-sided colonial that appears as though the exterior has never been cleaned. We would like to extend the life of the aluminum siding for couple of years by washing it. Do you have any recommendations for cleaning products? I have a high- and low-pressure washer available for the project.

- Michael Krar, Southington, CT


Steve Thomas replies: Exposure to sun, pollution, and the elements can turn siding chalky, faded, and porous, allowing dirt and mildew to penetrate the surface. I would try pressure washing, first with straight water on low pressure. If that's not getting the job done, do a test wash at high pressure in a place that's not highly visible. Some pressure washers develop pressure great enough to break a 2x4, and the last thing you want is to damage siding with high pressure. Then try scrubbing it with a biodegradable detergent or trisodium phosphate and hosing down with a low-pressure spray.


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