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Discussion Starter #1
I was wondering if the following would work well for a composite deck heavily stained with black mold. Power washing by itself never seems to really get it clean unless you go inch by inch.

What if I mixed a bleach/water (or olympic deck cleaner, or whatever) together with something to thicken it to a very loose runny paste. Anything. Flour, or anything similar. Just not something that will harden. Flour might be bad.

Then I use an extremely heavy-nap roller to apply it. It wont just fall between the cracks this way and will "sit" in the false grain.

I let it sit for some amount of time.

Then [garden] hose it off while it's still wet.

(?) The guys I've hired are having a hell of a time with this Rhino Deck.
 

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Sounds like the mixing, rolling, waiting, scrubbing, rinsing will add up to the same amount of effort as power washing with an added soap type solution.

I just powerwashed a large amount of retaining wall (about 1,000 sq. ft.)that was covered in black mildew. The powerwashing, without any solution, did an amazing job and only took an afternoon.
 

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rent a gas powered pressure washer if you have not tried one they go MUCH faster than the small electric ones. Not sure how much pressure that decking can take though?

plus if you do it on a nice hot sunny day its actually kind of relaxing (to me) to be out there in the sun with the water mist in the air :)
 

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Discussion Starter #4
rent a gas powered pressure washer if you have not tried one they go MUCH faster than the small electric ones. Not sure how much pressure that decking can take though?
I've used a gas powered PW on it before myself and it took forever to do a very small patch. The guys I hired used one even stronger than I used and used some special solution. It ended up with the "grain" of the composite (or whatever it might be in a composite like Rhino Deck) lifted up so high that the whole deck feels amazingly frictive. It is so to the point where I dare not have them do it again.....feels like the top surface of the decking was ripped up.

The idea I was interested in was because it did not require scrubbing. Just rolling on, and hosing off with no PW needed. {shrug} Sounds like the consensus here is that it's not that great an idea.
 

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For removing most dirt and grime, a simple soap solution and soft bristle brush works well. Power washers should not be used on composite decking as they may mar the finish and damage the decking material which happened to you.

Because of the organic ingredients in composite decking (wood), black mold can be a serious problem and should be treated immediately or as soon as possible when you see mold build up with a solution of ¾ cup bleach to 1 gallon of water and using a soft to stiff bristle brush work in the solution and then rinse off. You can also purchase a commercial grade composite deck cleaner and check with your decks manufactures cleaning instructions
 

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Discussion Starter #6
For removing most dirt and grime, a simple soap solution and soft bristle brush works well. Power washers should not be used on composite decking as they may mar the finish and damage the decking material which happened to you.

Because of the organic ingredients in composite decking (wood), black mold can be a serious problem and should be treated immediately or as soon as possible when you see mold build up with a solution of ¾ cup bleach to 1 gallon of water and using a soft to stiff bristle brush work in the solution and then rinse off. You can also purchase a commercial grade composite deck cleaner and check with your decks manufactures cleaning instructions
I used to use dish detergent with a stiff brush, and it only 1/3 removed the mold. I've tried bleach and the same brush, but it never sat on the boards long enough to do much. It always ran off the sides. It removed more like 1/2 of this mold I get.

I used a PW with water, and then with water + bleach, and was able to get it clean without marring the surface but it was excruciatingly slow.

I will try again with the brush technique you mention next time, but this time I think it will be much harder with this rough surface providing far too many places to trap the mold. :-/
 

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Discussion Starter #7
I may be soon asking if a coat of polyurethane is a bad idea. LOL
 

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Sounds like alot of aggrevation and time...

If it were my deck I'd either a) let it go all natural and not worry, or b) replace the decking with a material that won't drive me nuts...
 

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Discussion Starter #9
Sounds like alot of aggrevation and time...

If it were my deck I'd either a) let it go all natural and not worry, or b) replace the decking with a material that won't drive me nuts...
That's what I thought I had done with Rhino Deck. There *was* a manufacturing time where Rhino Deck had an endemic mold problem, but mine is supposedly after that moment. And it's not just the decking. The railing (cedar) was covered, the playset was covered, and if eons ago I hadn't filled the paint with mildewcide the fence would be blackened too.

And going all natural looks really bad. Black mold everywhere?
 

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Are you in total shade from trees? Maybe cut some down to let your yard dry out? If everything is covered then it sounds like no matter what you do it is going to turn moldy. So treat the problem at it's roots. Get some sunlight on it so it can dry out and naturally kill the mold.
 

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Discussion Starter #11
Are you in total shade from trees? Maybe cut some down to let your yard dry out? If everything is covered then it sounds like no matter what you do it is going to turn moldy. So treat the problem at it's roots. Get some sunlight on it so it can dry out and naturally kill the mold.
Nothing in the shade. Bright sunshine most of the day. On many of the mold parts it's in sunshine almost the entire day. It's on the SW side of the house, and the tree shade doesn't reach it. Mold is on the playset as well and the roof of that doesn't get a bit of shade ever other than maybe a cloud and nighttime.
 

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Nothing in the shade. Bright sunshine most of the day. On many of the mold parts it's in sunshine almost the entire day. It's on the SW side of the house, and the tree shade doesn't reach it. Mold is on the playset as well and the roof of that doesn't get a bit of shade ever other than maybe a cloud and nighttime.
Sounds like it's not mold then. I find it hard to believe that you have a deck in total sunshine that is engulfed in mold. Mold hates sun...
 
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