I've got some algae growth on my house and I am planning to borrow a buddy's power washer (I think it's 1750 PSI or so) to take care of it. I know the house was washed just before I bought it, so it's been done before. The algae comes off easily (I was able to easily get rid of some of it with a plain old car sponge).
Are there are any special precautions to take besides the obvious? I plan on keeping the pressure as low as possible (using the adjustable nozzle) and focusing mainly on the areas with algal growth. If I get that off and the rest of the house is the same color, I'm not going to bother.
I assume it's a simple job, but I wanted to make sure.
I'd wet the siding first and then take a pump up garden sprayer with a bleach/water solution and spray it on the siding, then use the pressure washer. The bleach will make for easier removal of the mildew/mold. Depending on how old and the condition of the aluminum's coating, it's possible that some of the paint might be removed also. This usually isn't a problem unless the siding is over 20 yrs old. If need be we can advise you on the prep and material for a paint job that should last 10yrs or more.
As always, when PWing, care should be used around windows and doors. You also want to limit upward spray that can force water behind the siding. The same goes for spraying at an angle at the siding joints.
I've read the bleach solution suggestion, and I'll try it if need be but I think I can get by with just water. It's a little over 20 years old, but it was washed four years ago with no ill effects that I can see. It seems to be in very good condition. Also, the pressure is relatively low (it's recommended for car washing as well), and I've been told that it will take off algae with no problems but it won't even get off all the dirt. I'm mostly concerned about the appearance as the algae is rather unsightly.
I don't have the option to completely avoid upward spray, but I will try to keep it to a minimum. There is one joint where some water will almost certainly get behind, but I think it drains well anyway.
Truth be told, if I had ladder access to most of the spots, I'd scrub it off by hand, but the washer lets me do it from a distance.
Run your finger across the siding, if you finger stays clean, you shouldn't have any issues with the siding's finish. If your finger tip turns white [or color of the siding] the finish is at it's latter stage and might wash off along with the dirt and mold....... but a clean house with some thin spots in the siding's finish still looks better than one that's dirty or moldy
Tags: power, washing, aluminum, siding, siding finish, upward spray, your finger
