In my opinion power washers have way too much psi and can potentially cause damage and drive water behind the siding. For a cleaner, I used Clorox Pro Results Outdoor Bleach w/ a 1:4 ratio. If you have mildew stains on your siding, “you need bleach”. Don’t waste your money on those siding cleaners. I tried them and they did not remove the mildew w/o a lot of heavy brushing. With the bleach, mildew disappears right before your eyes shortly after you apply it using for instance a pump sprayer. Buy yourself a a good soft bristle brush w/ telescoping pole (example: 12′). Also a smaller long handle brush for doing windows and hard to get areas. Be sure to put plastic over plants because the bleach will cause damage. Wet down plants thoroughly afterwords just in case there is any residual spray left behind.

Also, I completely disagree with those that say to wash from the bottom up. It makes no sense at all. You want dirt to flow from the top down. What’s key is to keep the siding being worked on completely wet and brush each panel side to side. I recommend washing on a moderately cool (calm) day, and plan to do the shady sides of the house if possible as the sun moves across the sky throughout the day.

Good luck!

Our method:
We presoak the dislodge debris and soften the fungus/moss/mildew/mold dirt. .We have several guys working. We use soft natural bristle brushes on a pole.. We scrub sideways and even tap a tap, or brush rapidly back and forth, up and down like a show shine perpendicularly onto the grain of the siding.

Pressure washers don’t get into the groves of the faux wood grain, .We don’t let detergents dry. We use “Simple Green”. We used to use generic cleaner….but was much more scrubbing. And now we have discovered commercial mold removal products, like the ’30 Second ‘ cleaner. But, its pricey. I will try bleach, borax, tsp, baking soda, and laundry detergent. Do not use laundry detergent with phosphates–that is a delicacy for mold. TIde will do nicely. And not liquid! use powdered! And remember ……..Water is your Friend! If the whole wall is kept wet, streaks aren’t a problem. Streaks could form if you tackle the top with a brush and let the concentrated cleaner dribble down the wall, remaining there longer than the cleaner you use when your lower, so it would be cleaning long enough to leave streaks. .We never had streaks. But we keep the wall wet and work fast. It all gets done withing 15 mins. And by the way, sprinkle tide on your roof a few times a year to kill mold. Lightly dampen it afterward with the hose so it doesn’t blow away.

And by the way, please don’t use newspapers to clean windows. YOu wil streak them up, and drag lint all over them. Just ditch the idea. Newsprint ink today is made with vegetable dyes, not leaded ink. In the olden days, glass was made with lead and the leaded ink newsprint would transfer into the scratches thus filling them. ..plus, newsprint is a disaster as far as lint goes. Use paper towel( gasp! perfect every\-time(avoid cheep brands)..

If you regularly clean your siding and it is not too dirty it probably will not make a difference if you follow common sense. If the siding is not cleaned often and or if it is very dirty or has a lot of mold or tree sap stains you probably should start from bottom to top and work is a small area less than 30 sq ft and rinse regularly. When you get to the higher top sections continue to rinse the lower ends and do not just depending on the runoff from the top. Don’t forget – RINSE-RINSE-RINSE

I usually brush off the siding first with a broom. Gets the webs and loose dirt off.

I mix a solution of 50% water/Clorox. Using a hand-held pump-up sprayer, I start at the eaves and spray about a 5 foot swath and work down.

Let it sit for a while, and the mold comes off with only a water spray with the hose.

Gives you time to spray a whole side and then hose off.

Whitens the whole house. I do it once every couple of years.