Why pressure (jet, power) washing a roof is NOT a good idea

August 08, 2020

Soft washing an artifical slate roof with Benz Bio Cleanze

A customer asked us, if it would be a good idea to pressure (jet, power) wash a roof prior to treating it with Benz Bio Cleanze.

That's a reasonable question.

You could jet wash a roof and then treat with Bio Cleanze.

But why would you?

High pressure jet/power washing decreases the lifespan of a surface by removing the protective surface layer. It's like exposing the surface to several years weathering in only a few minutes. Experiment on an area of reasonably fresh concrete and you will observe this for yourself.

Jet/pressure washing a roof would substantially increase the time a job takes, forcing you to increase the price to your customer and therefore inevitably losing some contracts because the price is too high.

Btw: The photo above is of Ben soft washing an artificial slate roof the correct way, treating it with Benz Bio Cleanze.


Q: "What would be the issues with using a jet washer with no chemicals added, aimed from a safe distance and using the blade nozzle down slope on interlocking concrete tiles to remove general soiling and vegetation, followed by an application of biocide to get under the tiles and kill off any remaining vegetation?"

We replied:

  1. The soggy mess of moss, etc, that jet washing creates can splatter surrounding surfaces and neigbouring properties, and will need to be cleared up and removed from the gutters.
  2. There will inevitably be a substantial ingress of water under the laps of the tiles because of the pressure being used. Clearly this will not be a good for the roof.
  3. The danger to the operative would be seriously increased because the only way a jet washer can be used to clean a roof is to stand on the roof and work down from the apex. And the only way to ensure the full safety of the operative would be to scaffold around the roof with a walkway of scaffold boards, again massively increasing the cost.

 

Whereas, when treating a roof simply, easily and quickly with Bio Cleanze:

  • When a contractor clearly explains to their customer the reasons for the approach they are taking, and explains how the treatment process works, most people are happy to wait for full results to show. (our website has videos showing this process happening through time)
  • The cleaning effect will be just as good, or better.
  • The surface will not have suffered excess weathering and reduction of life-expectancy, which means your customer's roof will last longer.
  • Treatment can usually be carried out safely from the ground or from a moveable tower.
  • The treatment is simple and consumes the least amount time of all soft washing methods (just requiring the scraping of any loose, dry – and therefore easily collected and removed – moss before applying Bio Cleanze).
  • The price a contractor charges can be lower than for other softwash methods, which means they will get more contracts.
  • No rinsing is required, further reducing the time a job takes compared to other cleaning methods.


We hope this clarifies the situation regarding the use of pressure / jet / power washing to clean a roof.

Click here to learn about Benz Bio Cleanze

Cheers,

Ben, Leo & Fiona

 

Click here to explore the full range of Benz popular softwash cleaning products

Benz Softwash Bio Cleanze DDAC biocide & Benz Softwash Lightning Cleanze SH sodium hypochlorite biocide


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