I’ve lived in this neighborhood for three years now, and the same thing happens about this time each year. After a campaign of flyers left on front doors, crews come through to power wash and seal “mildewed” fences. (I wouldn’t subscribe to any service advertised with those damn flyers, but that’s just me.)

The fences here are cedar planks, usually called privacy fences. We called them stockade fences in Oklahoma. And in Oklahoma we didn’t power wash them to remove “mildew.” The lovely, neutral gray color they took on after a year or two of exposure was the desired, expected look. We couldn’t wait until a new fence finally weathered to that soft color.
But here crews get lots of work and lots of money to return such fences to their pristine, fresh-cut wood color. Obviously it can be done. The fences look brand new when the crews leave, several hundred dollars richer and knowing they’ll be needed again in two or three years. It’s also a domino thing; do one or two fences in the neighborhood and suddenly the neighbors will be wondering if they need to “renew” their own fences to keep up with the Joneses.
Granted, there could be a regional color preference. “Weathered” in Oklahoma, “new” in Colorado. But this service is being sold as a “mildew removal” process. Mildew sounds undesirable, destructive, and unhealthy. Any normal person would want to get rid of it, right? But this is a very, very dry climate. I don’t see how mildew could develop here at all if you didn’t go out of your way to provide constant moisture.
Another approach is described in a local ad:
In the State of Colorado, it is recommended that you have your fence professionally cleaned each spring to remove the winter build up that occurs due to our varying weather conditions. Give us a call today, and find out how beautiful your fence can look again!
Recommended by whom? Winter build up of what? Snow? Water? These are residential fences, not highway fences getting splattered with road salt.
Yes, I live in a bubble of relative isolation, but this sure smells like a racket to me. (This rant inspired by the power washing crew next door … )
After every hurricane down here on the Gulf Coast, we have something similar as (what we call) Gypsies descend on us offering to repair everything from fallen trees, to leaking roofs, to replacing those same sail like “privacy” fences that wind up laying flat on the ground or just gone.
It doesn’t sound as if your laborers include a lot of con men, but we see more than a couple or three after each of these storms. My advice is never pay up front. Not even for materials. Always check for insurance and bonding. Never leave your property while they are working. Cross your fingers.