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Why can't a pressure washer be used to soft wash?

Discussion in 'Power Washing' started by Zen Lawn, Aug 31, 2011.

  1. Zen Lawn

    Zen Lawn LawnSite Member
    Messages: 77

    I apologize if this has been covered before- I did search the forum and couldn't find where this subject was posted...

    From what I understand, a soft wash is often defined as using low pressure, high volume with chemicals to clean roofs (especially asphalt shingles) to prevent unnecessary wear.

    If using a tip that lowers the pressure enough that you can use it on your hand without taking off the skin, wouldn't that be comparable to a 12v softwash system? Wouldn't the black or white tip be safe to use on asphalt shingles?

    Also, I've heard pressure limits set at 300 psi and 550 psi for composite. Could I get something comparable with a high pressure nozzle (for garden hose) or a pressure wand? What does 300-550 psi look like?

  2. Zen Lawn

    Zen Lawn LawnSite Member
    Messages: 77

    Maybe this subject has already been beat to death and I still haven't understood it yet...
  3. HighTide

    HighTide LawnSite Member
    Messages: 7

    Yes, I soft wash houses all day in the way you just described. However regarding the cleaning of roof shingles, you will not be able to get a strong enough chemical on the roof by downstreaming via the pressure washer. A 12 volt pump is the most popular means to get the stronger chemicals applied to a roof. Spray the roof chemicals on then go collect your check!
  4. JCinNJ

    JCinNJ LawnSite Member
    Messages: 159

    +1 - with the dedicated roof pump you can apply full strength or go the other direction and apply so weak you can drink it.

    With downstreaming a full strength mix still gets diluted and becomes even weaker
  5. Zen Lawn

    Zen Lawn LawnSite Member
    Messages: 77

    JC and Hightide- I understand now- a lot has to do with the mixture percentage.
  6. Roof Cleaning Raleigh  NC

    Roof Cleaning Raleigh NC LawnSite Member
    Messages: 67

    Rain knocks some of the granules loose. Think what 300 psi would do.

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