I have been asked this question lots over the years. Or a customer might say, ” Well, I heard so and so on the radio saying it’s terrible and shouldn’t be done – it damages your house.”
Power washing as I call it, or pressure washing, pressure cleaning, etc started taking off in the 80’s in the residential markets here in Vamcouver. Power washers come in different HP (horse power), usually range from 500 – 5000 PSI (pounds of pressure per square inch) and have a GPM number (gallons of water per minute). Your typical electric power washer from Canadian Tire to clean your car for 99 bucks might be a smaller unit at 2 HP, 500 PSI and 1 GPM. The standard unit used by most power washing companies would be an 11 HP unit with 3000 psi and 4 GPM. These power washers will normally get the job done. We use these type and can clean concrete sidewalks and driveways, patios, interlocking pavers, vinyl siding, vinyl decking, alluminum railings, cedar decking, stucco, etc. Most of these types of surfaces are fine to pressure wash for your average user.
I do believe some problems have risen from inexperienced operators of power washers. When customers ask me if pressure washing will do any damage – I tell them what I have learned: If something (loose paint, crumbling mortar, section of siding) will come off if I rub it with my fingers, it will come off when you power wash. Power washing is dangerous aound windows – period. I have seen (and damaged) window seals broken when powerwashed. (Thats when you get the foggy window between the panes.) I stay away from windows. Another problem area on any house or commercial building is doors. Although a house should be sealed up tight, doors tend to leak along the bottom and into the house, after years of the bottom rubber seal being slowly worn out. Again I know – I once paid $ 600 buck to replace my customers inside hand done door mat. I stay away from doors. The other areas to avoid power washing if you are inexperienced is wood decking as it might rip if you power wash to close – asphalt driveways -you can draw your name in it quickly if your not carefull, and roof cleaning – expecially asphalt shingles. Roof cleaning comes with its own issues -skylights, flashing, etc – but asphalt shingles will crumble if you power wash too close. I have learned the proper distance to power wash without removing the little granules, but it took years to learn. If your new at it – have someone show you how, or better yet call your local power washing company!
Hope that helps answer some questions you might have had.
Keep sending me questions, and I’ll try to answer them here when I have time.