Professional Soft Washing
The majority of professional pressure washers use a technique called “soft washing”. Typically less than 1000 PSI is used to clean a house. Very little pressure is used, with the surface being cleaned by the detergents applied, and then rinsed by the pressure washer. By using lower pressure, there is less chance of harm to the washer or the surface being cleaned.
Pros first pre-wet any plants and surfaces not being cleaned, then apply their detergent solution on the siding from the bottom up. The solution includes sodium hypochlorite and soap to allow it to cling to the surface more effectively. The solution is allowed to dwell on the surface until all the mold is killed. Any spots still left are hit with a second application of solution.
Once all the mold is gone, the professional washer rinses from the top down and washes all traces of mold and debris from the siding. Then the siding is thoroughly rinsed to remove all soap from the surface, and all plants and other surfaces are throughly rinsed with low pressure.
Higher parts of siding are reached using a special tip that can shoot a low pressure stream up to 40 feet. On very high parts a 6 foot extension sometimes is used, but all the washing can be safely from the ground without using ladders.
Houses can be washed faster and more effectively than using the “pressure cleaning” technique. Pros using the “soft washing” technique generally favor pressure washers that put out more gallons per minute (GPM) and have less pressure (PSI).
In summary, smaller one-story vinyl houses can be cleaned by do-it-yourself homeowners using residential machines, however for larger two-story homes with high peaks it is best to hire a professional pressure washing company that utilizes soft washing techniques.