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Advice for a newbie pressure cleaner

Jason Mullsey

New member
Hello from Australia

I have a commercial window cleaning business and one of my clients has asked to quote to pressure wash the roof of the building. The roof is pretty flat with on a gradual slope for the water run off. Most of the badly affected areas have just a build up of leaves. The area is approx 3500 square metres or 37500 sq feet.

I have a few questions that I hope I can get answered in this forum.

1.Can you please give me a rough cost or an average cost per sq m or sq foot

2.Is it advisable to remove all of the loose debris first or just pressure wash it off

3.If I am just removing mainly light algae growth in other areas is just a cold water pressure washer suffiecent

Any other advice would be much appreciated.

Thanks
 

Bill Booz

UAMCC Board of Directors
Hi Mullsey,

I need to know a little more about this roof and your equipment to help. Is it a flat rubber membrane roof? Do you know who manufactured it? What kind PSI and GPM pressure washer do you have? What do you have for applying chemicals? Do they really want it cleaned or do they just want the leaves and slippery spots gone?

Help me out with that info and I can help you with a method and pricing.

You will probably blow off all the leaves first. Have a guy push them to one end of the building with a blower.
If its a rubber flat roof than yes cold water will be fine. You will want to apply a cleaning solution that wont harm the membrane and lift the algae so you can gently rinse it off. Check with the manufacturer (if possible) that your chemicals will not void the roof warranty (if applicable). You may end up using a form of bleach to loosen the algae. Always inspect any roof you are cleaning for damage before and during the cleaning process. Tell the customer that you are cleaning within the manufacturers recommendations and following an outline that will produce a safe and effective result for the customers need.

Answer those other questions and I will have some better answers for you.
 

Bill Booz

UAMCC Board of Directors
Your welcome Mullsey,
Well, I would probably spray a mild chlorine solution on it and then it will rinse off extremely easily with the pressure washer. You could downstream some sodium hypochlorite on it. Sodium Hydroxide will work as well if it's oxidized and you have to remove the oxidation then a brush and Hydroxide will work. You will have to be careful as it will get slippery, so you may need some fall gear in place depending on if they have a parapet wall to help protect you. A soft truck wash brush may also help loosen things faster than the pressure washer alone would. That 2,000 psi is plenty. If you have some larger tips than try using one and see if you can rinse large areas at low pressure, after the mild chlorine solution works on it. I don't know you're market in Australia, but I sent you a private message with some pricing suggestions.

If you cannot use chemicals, the pressure washer alone will work, but will be slower. Wet a large area and let it soak, as this will at least help loosen the dirt if there are no chemicals involved. Just keep this in mind for time=price.

Now the harder parts you will have to figure out before you price it. Where is the water access? How much water hose is needed to reach the water access for each move you will make. How much pressure washer hose will you need? How will you access the roof?
With that info you can make a game plan for your cleaning.
 
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