Deck Cleaning 101

Purpose of This Post:

The purpose of this post is intended as an instructional piece that can be a source for those with questions on deck cleaning now and in the future. I am sure there are some on here that have comparable projects that the results exceed my humble efforts. I would like to invite other experienced wood cleaning contractors to add to this post with pictures of their projects. I would encourage you however to utilize the same format so that a new contractor will have a complete understanding of your project in order to gain a complete picture of your process and how it may relate to their project.


This particular deck was a 2 1/2 year old deck, pressure treated pine, never stained, and exposed for most the day to direct sun, especially in the afternoons. Though not very dirty, the sun had done significant damage and the new homeowners wanted it prepped for staining. It was a simple 14*16 though with steps, pickets and handrails - adjusted total square footage was 463 sq/ft. Height was about 3’ off ground on low end to 5’ off on high end.

Location - Greenville SC

Price - $230 ($.50/sq/ft which is our minimum). Factors which normally affect cost include how poor of condition of wood - how dirty - height - surrounding vegetation

Time - Approx 1 hour 40min

Before Pics:


Cleaning Process: Prewet, let sit for about 10 min. Downstreamed straight SH with just a pinch of sodium hydroxide and elemonator utilizing my 4gpm machine which pulls around 10-1. Total mix used was about 1.5 gal.

Once done applying mix utilized 8gpm with adjustable wand to clean at approx 1400psi

After cleaning pics:

One board left

Note to new contractors here - when cleaning pickets hit them at a 45deg angle. That way you catch 2 sides of the picket when cleaning with one pass and then when you go to the other side hit from the opposite 45 and presto you’ve cleaned the whole picket with just two passes. Also be careful with your up and down motions that you don’t carry too far onto bottom or top rail or you will have lighter marks from double cleaning where you have overlap. You’re better off cleaning pickets first and then the rails since overlap marks will not be nearly as visible on the pickets.

Once done cleaning applied Oxalic acid 10 oz/gal. with 2 gal pump up sprayer. Used 3 gal total. I normally prefer to use citric acid to brighten and neutralize but in this case some nails were starting to rust, in which case you’re better off using Oxalic.

After Ox applied liberally and still wet from rinsing after:

After Deck had dried:


Same exact process for me last Friday, but my pics aren’t as good as yours!


Thanks @Racer for another help- and insightful post. This is one reason why I like this forum, because of members like you and the willingness to share their expertise. Thank you!



Same process here. On the fence i did not use ox or sodium hydroxide. On the deck i did use ox and it brightened the wood and made it look amazing. Im going to add alittle sodium hydroxide next time.

For they guys using sodium precarbanate on wood. What is your main reason for using it over SH. Im finding SH easier because i can just downstream it straight using my 4gpm and i dont need warm water and it seems to do a better job.


The main reason for sodium percarbonate is you get a lot less furring or risk of furring. It doesn’t clean as well but a quick hit with a deck brush takes care of that. If you’re going to stain afterwards it keeps you from having to sand as much. I use both but it just really depends on the deck.


Well put together thread @Racer. Nice work !


Looks better than new @Racer

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Wow @Racer That looks great and your instructions are amazing! I was just re-researching deck cleaning because I have someone who wants me to clean theirs and I haven’t done one yet. This thread will be super valuable to us who are just starting out. Thank you!


@Racer you are the Bob Ross of Pressure Washing. Thank you!!!


Type of wood: Pressure treated lumber (?)

Chemicals used: 2.5% SH, Citric acid (1 cup per gallon).

Process: Pre wet wood, apply SH using a 12v pump, dwell for about 10 minutes, medium pressure rinse (1000psi), applied SH again, dwell for about 5 minutes, medium pressure rinse again, post treat with Citric acid, low pressure rinse off Citric acid (no pressure required).
Note This deck was bad, applying SH and medium pressure rinsing twice is not the usual process. It was however necessary to clean this deck.

Time: About 3 hours including set up and packing up.

Cost: I only ended up quoting my minimum charge of $189.00+ after meeting this customer. Though he lived in a nice house and area, he was going through some very unfortunate times with his son being sick and explained how he didn’t have time to do it himself and his wife wanted it done. At that point I just told him my minimum charge and set up a date.

Area: Southwestern Ontario, Canada.


That looks amazing. I may need to pick up some citric acid but what I gathered from Racer’s post is that the OA helps with nail rust more. I would honestly just prefer to citrus scent more than anything and those results speak for themselves.


Thanks! I honestly have had better results using oxalic than citric but I may not have applied it liberally enough. That was my first time using it

Now your just show boatin :joy:
Looks nice !

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Smells like your in an orange Grove my friend, I use it alot


:grin: thanks @Hotshot

I’m ordering some then.

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It was actually cheaper than oxalic when I ordered it off Amazon

I get a good wiff of the citric and all my lovely acids all the time. And I’m still Nurrmill…:crazy_face:


$94 for 55 gallons @ Hydrochem. But the shipping sucks@ 150.

That’s crazy. I picked up 15 pounds of OA powder for something like $40 I think. Give or take a few dollars.

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