Updated: November 2017
Power Washing Services:If you live in an area with constant drizzle and not a lot of sunshine then odds are you will have to power wash things like your deck, house, or driveway in order to keep mildew and moss to a minimum. I reside in Portland, Oregon so we get our share of rain and cloudy days. Therefore, moss buildup on my concrete driveway and sidewalks is a constant battle. I own a low powered pressure washer that plugs into an electric outlet but it isn't powerful enough to spray away the moss that grows on the concrete. I recently looked into power washing services that will come out to your house with a high powered gas pressure washer and clean things up. Some charge a flat fee while others base it upon square footage or an hourly charge. We found that professional power washing services charge about $.08-$.35 per square foot depending the type of stain or dirt that needs removing. Power washing vinyl siding is a big job and most services go by square footage on this one.
I had a service power wash my roof twice now. It's called roof restoration, but it's pretty much a thorough power washing of your roof to get rid of mildew and mold that eats away at the shingles and shortens the life of the roof if gone untreated. My driveway had never been pressure washed until recently and the moss building was getting dangerous as several kids and adults had slipped on the slippery surface. Power washing a concrete driveway can cost you $150 to $400 - depends on the size - and some say it's worth renting a pressure washer from a rental service for a job like this. It's not difficult and many homeowners can do it themselves in 4 hours or so. Overall, power washing is considered a beginner/intermediate type of DIY project around the house. We do however warn homeowners to be careful if they plan on power washing their house since you can damage and peel off paint if the pressure washer is too powerful. Power washing a house is a huge job and probably best left for the pros. Walkways, decks, driveways, etc. - these all are smaller jobs that are easier to do. If you allow the moss and dirt to buildup over the years (as I did), then an underpowered pressure washer may not do the job. You'll definitely need to go with the gas powered machines that have lots of concentrated power to remove moss and other stains. One of my neighbors borrowed someones gas power washer and it was so powerful it literally removed small rocks from the aggregate driveway and blew them into his house causing damage. That's not a good thing, so be careful and always start with less power versus more. The person I chose to power wash our walkways and driveway was a local handyman and he is well recommended by friends. See what you can find in terms of power washing services via word of mouth and then check on websites like Craigslists. Get a few estimates and then go with the person or company you feel most comfortable with. Always get the price in writing before starting - we heard some folks say they were verbally quoted a price but by the end of the job it had changed (cost was higher than originally quoted) and they felt rooked and scammed.