Ask the Architect

Will a deck survive power-washing?


Q. I saw an advertisement for power-washing and handyman work, and want your opinion about whether to try to restore my old deck, which hasn’t been power-washed or stained in years. Some boards have bent upward. Should I try to restore the deck by having bad boards replaced and then power-wash and stain the rest, or should I replace all the boards with the new plastic wood? I’m told that the “false” wood will last longer. What would you do? I need the siding and patio cleaned, anyway, so I’ll still do some power-washing.

A. The key word here is “power.” If too much pressure is applied, you can do more damage than I suspect you already did. Ordinary washing and brushing the boards with a safe cleaning detergent with hand pressure is really all that’s needed. People used to do that, but now want instant satisfaction, and why work harder if they can use a device to do the work for them?

I’ve seen many instances of good finish materials ruined by too much water pressure, and testified in court to explain, in great detail, what water, under different gradients of pressure, can do to vinyl fences and handrails, wood surfaces, siding, concrete patios, granite outdoor kitchen countertops, stainless steel and window frames. In one case, the homeowner was suing because all of the above had been badly etched by water. Since water “jetting” is one method used to etch letters into gravestones and those bricks donated with a name on them in sidewalks, it is a powerful force.

Ever notice that there are many services that help perpetuate one another, knowingly or unknowingly? It’s kind of a system of balancing one another economically. For example, I remember, when I was a kid, my dentist always had a big candy dish in the waiting room filled with hard, sticky caramel candy, which I’m certain helped ensure that I would return to see him, again, and I’m suspicious that the guys at the car wash are related to the guys with the leaf blowers who dust up your car right after you get it cleaned, assuring another trip to the car wash. Balance.

The people who don’t pick up nails from the street as they load and unload construction materials at a job site and the tire stores have another system, which leads back to power-washing, a process that all but guarantees that the handyman part of that advertiser’s business will be perpetuated, since they’re creating a need to repair what they damage. When it’s not done with caution and care, power-washing can destroy the surface of nearly everything it’s applied to. Once etching takes place in wood, the fibers separate and the wood becomes like a sponge. The shiny surface on vinyl will pit, and those tiny pits become a home to mold and mildew. Synthetic decking, instead of cleaning the old boards, is a better, longer-lasting option.

© 2018 Monte Leeper. Readers are encouraged to send questions to, with “Herald question” in the subject line, or to Herald Homes, 2 Endo Blvd., Garden City, NY 11530, Attn: Monte Leeper, architect.