Pressure washing a rubber roof

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COMer

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Has anybody tried to wash their rubber roof by using a pressure washer?  I can't remember anybody commenting on this and don't see any warnings in my roof maintenance literature.  I wonder how hard it would be on the roof (using the proper settings) as opposed to using a bristle brush which is recommended.  It would be a lot easier if it would do a good job and not damage anything.
 
I would be VERY concerned about possible damage. A rubber roof is just a fabric covering coated with EPDM.  Let that high pressure spray get too close for a second and you are going to either scallop out the EPDM or even cut the fabric.  I'm sure it can be done successfully with a lower pressure washer (NOT one of those 1500-2000 psi jobs) and a suitable wand (no needle sprays!) and strict attention to what you are doing, but I think it is still risky.
 
My personal experience with a membrane roof is that the "dirt" for lack of a better word, is a combination of mildew/black particles and other forms of discoloration that are pretty well-fixed (almost embedded) to the rubber.  The surface is not slick or glazed and whatever dirt is on it is attached pretty well.  I think (I've not tried it) pressure washing would achieve some "change in color", but to get it really clean, and particularly if you are going to treat it afterwards with some recommended dressing, then it's gonna take that brush and a lot of elbow grease to get it clean.  If a detergent or some form of soap can be infused into the pressure washer stream, then that might make a big difference.

If you choose to use a pressure washer, I'd advise being very careful how you "direct" the pressure stream onto the roof.  RV vents do not "seal" air tight and depend on rain falling from above not to leak.  A pressure stream directed close to the base of a vent is going to wash up and under the vent lid and fall inside.  Same goes for refrigerator vent as well.  Anything going into the vent stacks for grey and black water would just fall into the tanks with no harm done.

 
I have a relatively low pressure nozzle for my power washer that I use for washing automobile wheels and for washing salt off my fishing truck and equipment.  I've used it to pre-wash the EPDM roof of the Bounder.  It's especially good for loosening leaves and debris that settle between the roof edge and main awning roll.

As others have said, be very careful with the force and direction of the water stream.
 
I have, and had no issues.  As folks said above, caution and pay attention to what you're doing.  Here's a few pics of my job.  You can see the before, during, and after.


 

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Sounds like it may not be worth the risk.  And if I do try it, I should start with a low pressue nozzle.  My washer has a collection of nozzles with various forces.  I just got to figuring that it would not be any harsher on the roof than scrubbing with a bristle brush which is necessary to remove the junk.
 
Mine just has an adjustable spray nozzle, and it did just fine.  I had it at a fairly wide setting and no problems.  You can really see the difference in that second picture.
 
I'd be a little cautious with a pressure washer. I just did mine, started with Spic & Span which did a fare job. When I ran out I picked up a bottle of Thetford Rubber Roof cleaner. It did a very good job. I just put a ladder against the side, used a fairly stiff brush with about a 6' handle, wet it down, scrubbed, and rinsed. Every time I moved I also rinsed the sides and kept them wet to prevent streaks.

In this day and age it's refreshing to buy a pruduct that does what it says it will.
 
Dicor and Alpha, the distributors of most all the rubber & TPO roof materials used in the US on RVs, recommend only a medium bristle brush for rubber roof cleaning. Never a stiff bristle brush.
 
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