cleaning vinyl siding?

I'd contact a local siding company and ask about the power washer. Could be mold or insect dew (poop). There are cleaners available on the market - spray on, just hose off - be careful of plants around the house.

Kim

Sounds like artillary fungus. The spores are a bitch to remove. YMMV

I have heard, I think on the Jon Eakes show, that power washers can put water inside the walls. It goes under and thru the little vents in the siding. We have a similar dirty siding problem with what could be mildew (very shady area) and will try one of the cleaners that attach to a garden hose.

Joe Ontario

I get a lot of dirt from a road that goes down one side of the house, as well as green mossy stuff that would like to grow on the siding. About once a year I mix up some cleaner w/bleach in one of my garden sprayers, spray it on the siding, then get a car wash brush that attaches to a hose, and brush/rinse the whole thing. Works great, is pretty quick, and hasn't harmed anything it the last 7-8 years. I'd be afraid that a power washer would not only get water behind the siding, but might even damage the siding itself.