I went and looked at a job today. The deck is old and needs work. They replaced some boards already but it really need to be scraped sanded and painted or stained ( by someone other than me) It doesn’t have a ton of organic on it so I was thinking I would use a precarb like F-10 coat the whole deck. Agitate with a brush and then rinse with a higher than normal pressure to try and remove as much old paint as possible ( getting it paint prep) I’ll put some pictures up. Let me know what you think or what you would do. If F-10 isn’t the best I can treat with sh
You don’t want anything to do with that mess
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Hit with SH or SM.
Hit with more pressure than normal to try and remove the loose stain.
Let customer know they will have a lot of sanding to do.
Make sure the customer knows that most of it is not going to come up with the process you’re using. It will get a lot of the loose paint, but even then, you won’t get it all.
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Unless you moonlight as a deck builder… 
I’m washing the house and doing a little roof cleaning for them also. I told her it’s not going to look like new, I also told her it’s been neglected for a long time and that they would definitely need to sand the entire deck afterwards and paint or stain. I just figured I could clean up the dirt and grime and the Mildew and then if i hit it with pressure I could save them some scraping
What is SM?
Sodium Metasilicate
I always recommend letting the painters do their own prep work.
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Oh man I get calls all the time asking if I can ‘remove paint from my deck’ and tell them I don’t use high pressure on wood.
The problem is they usually don’t.
How is this exterior cleaning?
If you hit this deck with SH and then rinsed, if they were going to sand and paint afterwards would you need oxalic acid like you would with a normal deck clean? If you don’t use it will it pose problems for painting or staining?
No, you don’t need oxalic on 99% of decks anyway.
SH and rinse. Tell them you can blow the paint chips off of they are getting it painted but you won’t pick them up. Otherwise Sh and rinse. If you are there for just the deck and not the house and deck… walk
My mistake…I thought it was generally required to neutralize and brighten after SH.
I’m doing the house and the roof. They asked me about the deck. That’s exactly what I told them. I told them it needs to be sanded and painted. I explained nothing I do will fix it, it’s been neglected for too long. I told them if they wanted to pay for it I would wash it quick to remove the dirt and mildew and that in the process I could blow the loose paint off to save them on scraping but I wouldn’t be responsible for cleaning or disposal of the paint chips. I also stressed that sanding and painting would be required after.
So we will see what happens
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I’ve never put bleach on a deck. Pressure tested wood has copper in it and bleach breaks it down. I only used potash on decks. No one used oxalic until 10 or 15 years ago when vendors started pushing it. It may help, but I never saw the need for it. But I’m not a wood guy, we may have done 1500 decks or so way back in the day but not any more and I’m sure there are better wood guys here with advice
That’s why I wouldn’t touch it. Prep is 80% of the job, washing is 20% of the prep.
Many would disagree.
See:
It is.
