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Helping son with a DIY project. He wants to paint or stain his deck stairs.

He doesn't know if the black marks are dirt or mold.

What steps should he take before painting or staining them?
Power wash cleaning? Bleach/water cleaning? Sanding? Priming?

This message has been edited. Last edited by: nance425,

If he intends to use the stairs in the winter do not paint. It does not hold up well to shoveling or even stiff brooming.

I'd clean and use a transparent stain that will soak into the wood. Do not use an opaque stain... it is the same as paint.

hey metwo, thanks!
What would you clean them with?

Nance,
There are a variety of spray on deck washes. I've used a pressure washer on my deck but you need to be careful if you have a really high pressure one. You can drill holes in the wood with a high pressure washer. You can certainly raise the grain with one and make the deck fuzzy. My deck looked a lot like your sons a few years ago. I pressure washed it and used an opaque stain as the grain wasn't anything special on my deck. I just used a spray on product on my deck this weekend to clean it. First time I've done anything since staining it 3 years ago. The opaque stain (Sherwin Williams latex stain) is holding up well. I don't need to shovel my deck most years, and this past year I didn't need to broom it off either. My winters in NC are considerably milder than yours in MN so your results may vary. I stained my deck one shade darker than the sage green of our siding. I did the rails in the same color as the trim on the house. I'm pleased with the results, but one thing with an opaque stain is cracks and joints REALLY show up so you need to caulk the joints in your railing. With a translucent stain it isn't as much of a problem. Avoid products like "Thompson's Water Sealer" it is useless. Any product that proudly says in their commercials to apply it every year isn't worth the time it takes to apply let alone the cost of the product.

Hey thanks, Sparky.

I'm thinking the darker spots are not mold, just dark dirt??? Do you think Behr Premium 2-in-1 Wood Prep is good enough to use as a cleaner? And then spray down with a hose? He doesn't have a power washer, so he'd had to rent one.

000http://www.behr.com/cma/Behr/Marketing/Products/product_sheets/63PSR710.pdf

I haven't used that product. Lowes is 2 miles from my house, Home Depot is 10 so most of my shopping is done at Lowes. I used a hose end applicator for cleaning my deck on Saturday. It worked OK, but I did need to scrub it a bit. I'd bet the spots are mold not just dirt. MN is still a bit humid, not as bad as NC but not NM like either.

so do you think we should do a bleach/water solution instead of that Behr product?

I haven't done a deck in some time. When we bought the house the deck was painted. Once that went to pot (2 years) we sanded and went with opaque stain (which has to be worked on every year!!grrrrrrrr) which is why I know that paint and opaque stain do not hold up well.

But I was cleaning a wooden porch down south and used an oxygenated bleach. I could not find the large liquid containers that you dilute so I mixed oxyclean with water. Let it sit on the wood about 3 minutes and wiped off. Compared this to some bleach/water I did on another section (that I had to scrub) and the oxygenated bleach won hands down.

It is so easy that if I were you I would give it a try on a small section and see if it works. You might want to broom it before rinsing because of the dark spots.

I understand that some of the deck cleaners sold use oxygenated bleach though they do not use that term so I cannot tell which ones they are.

Once clean there is not reason you have to stain or paint the deck. It can just be sealed. Just another option.

metwo - DS had to replace some boards on his stairs. You might be able to see them in the pic. So, he has to stain or paint, so he'll have to do all of the stairs as well to match, right?

So, you're saying to just try Oxyclean? I'll let him know. I've not heard the term "oxygenated." Wonder what the difference is vs bleach and water solution that makes it work???

Hmmm, opaque vs translucent. I'm sure he wants something he doesn't have to do every year. Will a "sealant" help with that?

This message has been edited. Last edited by: nance425,

In my opinion some terms have changed over the years mainly due to marketing. I learned in my early years that 'stain' penetrates the wood and grain shows through. Because it actually is absorbed by the wood it is long lasting (years) and is only lost when the wood is actually worn away.

Paint sits on the top of wood. Therefore (in my opinion, of course) opaque stain is a contraction in terms. If it is opaque it is not a stain.

Now that said, I know a lot of people like opaque stain but my experience has been that a porch paint is longer lasting.

Now as to oxygentated bleach: It has been so long since I read up on this I don't know if I can get all the terms right. Regular bleach is sodium hydro..... (I forgot the rest) and oxygenated bleach is sodium percarbonate often with soda ash and some other stuff. Oxy-bleach is safer to use and allegedly will not harm plants or grass. I know it does not harm grass because I used it on a patio.

Based on my experience it does a great job with little effort and you do not need to wear protection like you would with regular bleach. If you were to buy a deck wash I would look for one with those ingredients (it will likely not be called oxygenated bleach). But I did not know all that at the time so I just mixed up a strong solution of generic oxyclean.

I have to stress that I am not an expert... I can just tell you about my experience.

Let us know how it turns out. It is August and you don't have a lot of time before the snow flies

thanks so much metwo...I will indeed ask DS to post some pics of his finished "clean up." It might take him awhile, though.

And you're right about the snow flyin' soon. I will miss our 90+ weather. I kinda liked it.
Heading up to Duluth next week. Wonder if I'll have to pack my winter coat....

well, Duluth has its own unique climate depending if you are at the water or up the hill, as I am sure you know. Sooooooooooo, maybe you should take a winter jacket

Gene Austin's Home Repair Q&A column in our paper yesterday talked about cleaning decks without damaging the plants around the deck. He recommended Jomax (the hose end product I used) or oxygen bleach (aka Oxy-Clean). To do it with Oxy-Clean put 1 cup of Oxy-Clean in a garden sprayer and 2 gallons of warm/hot water. Spray it on the deck, let stand for 5 minute and scrub any mildewed dirty areas with a long handled brush and then rinse. It is a good idea to hose down your plants before and after treating your deck. Doing this on a cloudy day will give you a longer working time.

sparky, thanks so much for thinking of us when you saw that article. Sounds like that's the thing to do.

If you're in Minnesota, I'd highly recommend buying the strongest deck stain you can find. I know my winters in Boston are comparable, and we bough a heavy-duty stain after a simple wash & dry during the winter. Those black spots are from the wood, and will actually look pretty nice once the stain is applied.

laurastewart - just saw your reply. Thank you so much.