Prepping Your Wood Deck – Cleaning

Dirty DeckExterior wood decking when left neglected oxidizes from the Ultra Violet rays from the sun. This will patina the exposed layer of wood cells turning the deck gray. Cleaning the deck first will a deck cleaner will remove this layer of graying wood cells while removing accumulated dirt, grime, mold, mildew, and algae.

Prepping your wood deck is the singular most important step when it comes to getting maximum performance out of your deck stain. Failure to prep and your stain will fail faster then it should and will not give the wood it’s natural beauty.

This article will go over the needed steps to properly clean your deck prior to applying the stain.

  1. Make sure that the deck is clear of all furniture and grills prior to starting.
  2. Decide first if you should use a deck cleaner or a deck stain stripper. Use a deck cleaner if the wood is gray and dirty. If you have am old deck stain that needs to be removed then you should use a deck stain stripper as the deck cleaner is not aggressive enough to remove stains.
  3. Pre-wet the deck first before applying the deck cleaner. Take precautions to wet all vegetation and the surrounding house. The majority of deck cleaners will not harm plants as long as you pre-wet and rinse off any residual cleaner that comes in contact with the plants.
  4. Wait about 5-15 minutes to let the cleaner activate. If needed, mist the deck with water to keep the cleaner from drying on hot days.
  5. Using a stiff scrub brush, starting agitating the deck until the wood comes clean. Using a pressure washer at 1000 psi or less will speed this process up.
  6. If any stubborn areas persist then repeat the process.
  7. After deck is thoroughly clean make sure to rinse the house, deck, plants, etc to remove all of the loosened grime.
  8. Using a Wood Deck Brightener will give the wood and added boost in appearance. The brightener neutralizes the deck cleaner and “brightens” the wood to a more natural state.
  9. Let wood dry a minimum of 24-48 hours before applying a deck stain or sealer.

See here for a list of deck cleaner reviews

70 Responses to “Prepping Your Wood Deck – Cleaning”

  1. crudbusters says:

    Great tips. The only thing that I would add is: while cleanin ga deck start at one end of a board and work it all the way to the other end. DO NOT stand in one place and work back and forth. It will leave line in the deck that will show through after a deck is sealed.

  2. Jason Carpenter says:

    Thanks for sharing these useful tips. I think they'll be really helpful. I'll bookmark your blog for more useful tips. Keep it up!

  3. cn78 says:

    what should i do to prep my new cedar decking before staining?

  4. Cathy says:

    I have pre-treated wood on the deck floor and then cedar rails and banister,built in May of this year. Do I need to use deck cleaner and wood deck brightner since it is new, before staining? I was told to wait and stain early fall,is this correct? Also, it appears that hornets are drilling holes in my banisters,any suggestions?

  5. christopher says:

    what happens if it rained lightly during the night and my Arborcoat was applied 12 hours prior?

  6. Judy says:

    I have a deck that is half covered and the other half is not covered. It has of course not weathered the same. The covered part after 6 years is just beautiful as it was when first stained. The open half is dark and unevenly stained since I have only stained that half. Don't know how to make it look evenly stained…

  7. Diana says:

    My 1200 sq ft cedar fence is in good condition but it's due for another coat of stain (starting to gray) and there are black mold spores on about 60% of the surface which I want to remove before re-staining. The fence is shared with my neighbours, and trying to address the mold on the other side of the fence is not likely, which means some mold will remain in the wood, even if it's not visible on my side. I live on the Prairies so the climate is usually relatively dry.

    I think the oil stain (SuperDeck Natural 1910) applied 3 years ago could possibly be promoting the mold. I have a cedar cold frame (for growing vegetables) that has no finish/stain (it's gray) and also no mold, even though it's right next to my moldy fence.

    Today I experimented using only a cleaner or brightener or just water to see which was most effective at removing the black mold spores and the dark gray stains. All required considerable scrubbing which actually damaged the cedar so now it will have to be lightly sanded to smooth it out. It seemed the scrubbing action was key to removing the mold. The brightener seemed the most effectively but not to a significant degree. The water alone with scrubbing was moderately effective. We also sanded a couple of panels with a belt and palm sander. Bleach (100%) in a small test area removed the black mold with no scrubbing. I don't want to use really strong chemicals to remove the spores for the entire fence.

    1) What method would you recommend for removing the mold: a) sanding? b) power washing? c) brightener?

    2) If I switch to a water-based stain, do you think there will be less mold growth in the future? Would you recommend a water-based stain in this situation?

    Thanks very much!

    Diana

    • Diana, I would clean with a deck cleaner and rinsed with a pressure washer. Brighten when done. Water based stains are not prone to mold growth. I think Defy Extreme would be a great choice for this.

  8. Dave Boulderite says:

    I live in Colorado , southern exposure and have an upper story redwood deck that's about 12 yrs old. I recently replaced a few boards using thompsonized southern yellow pine instead of redwood and stainless steel screws. I'v done a lot of reading on yr site and it seems that TWP 100 stain is a best bet. I'd prefer to simply prep the deck with the restore a deck system, and use my garden hose to wash that off, ( the other option is sanding- a lot more work/cost/time,I presume) but I'm worried that the washed off Restore a deck chemicals might do damage to the underlying joists or integrity of the upper deck sealant/membrane system , which I'm told by the orig builder is an EPDM rubber membrane, with sleeper joists. That's an important issue, since directly underneath the upper deck is my foyer and downstairs bathroom. So far I've never had any apparent ceiling leaks. So my questions are:
    1. Is it reasonable and safe to skip the sanding process and just use the Restore a deck system – cleaner and brightener and would those have a potential to mess up my upper deck membrane?
    2.Can/should I do this whole deck restore process now , or rather wait til late spring ( our weather is variable)- what stretch/duration of weather is optimal for this work?
    3. Are any of the TWP 100 stains only a 2 coat process or are they all 2 coats? I'd prefer ultimately a lighter colored deck than a very dark one( esp in summer when it gets hot).
    4. What's the reasonable duration/#years I can expect from a TWP job, if done right ?
    4a. Is TWP 100 a good choice for Colorado ( 4 distinct seasons, hot dry summers up to 95+, winters with 30-40 total inches snow, altitude 5400) or do you strongly favor another deck stain?
    ** I'm more concerned with protection and preservation than sheer aesthetics in the end.

    • Dave Boulderite,

      1. Restore-A-Deck products are essentially harmless to surrounding areas. We have never experienced any issues when using them near rubber or vinyl.
      2. I personally would wait until spring since the outdoor season is over.
      3. Lighter colors will fade/fail faster then darker colors especially in high UV areas. The 100 is a 2 coat system. You may be able to get by with 1 coat in the 1500.
      4. 2 years maybe 3 on horizontal surfaces.
      4a. TWP would work well in your area.

  9. LeVerna Mallory says:

    Interested in ordering Armstrong semi-solid. This product is not sold in my state. Would like to get idea of the colors. Would like brown but not a flat brown…something with a rust undertone would be preferred.

  10. dan says:

    I power washed my deck today and after it dried some of the wood was a blonde color and some of it was real ash white, why the difference? I also noticed I had some stop/start spots from powerwashing, Im a rookie, so will those show up in a darker semi transparent stain? will sanding even them out?

  11. Amy says:

    I would like to try to apply TWP 100 or 1500 to my Cedar deck that currently has blackend Red Label Penofin Rosewood Oil Do I need to strip/brighten, or will clean/brighten be enough prep?

  12. Paul says:

    I installed a pressure treated deck around a year ago. I was told to wait a year afterwards for weathering purposes. The wood looks good but gray in some spots. I power washed today but it wasn't really that dirty. I do notice a few dirt spots that never came up and also some brighter spots than others. I generally go to sherwin Williams for everything paint related but I can go elsewhere. Can you please give me some advice on what exactly to do from here? For example if I should use a cleaner what kind of cleaner should I use. I feel as if the wood could be cleaner or brighter but the power washer just didn't get that much up. Then should I use wood brightener and so on. I used the premium pressure treated from Home Depot.

  13. Stephanie Ford says:

    I cleaned my cedar deck 3 weeks ago and I have not been able to stain it yet because it has been raining non stop. If the forecast is correct, starting tomorrow it will not rain for several days. Since three weeks have gone by do I need to clean it again? Since the wood is so saturated would it be ok to give it Friday and Saturday to dry out and then stain it on Sunday?

  14. Stephanie Ford says:

    I cleaned my cedar deck 3 weeks ago and have not been able to stain it because of the non stop rain. Finally today (Friday) and tomorrow it is supposed to be 83 degrees. My deck is in full sun. Will those two days give my deck enough time to dry so I can stain it Sunday? It is supposed to be dry for several days but I can only stain it on Sunday since I have to go back to work Monday.

  15. Nick says:

    I was planning on just cleaning my deck, so silly me, I bought a wood cleaner, and went to town according to all the directions. After spent a good amount of time in the sun, I came back in here and read that "Deck Cleaners" are used for the prep of (re)staining a deck. That was not my intention at all!

    So now, what are my options? Not stain it and what happens?

    Or brighten it and then restain it?

    Thanks

  16. Angela says:

    Hi thank you for your helpful website.

    My husband and I are new home owners, we have a very large wooden deck out the back that we have applied a stripper to, the deck is now a very pale grey colour- I'm wondering if this is how it should look? We went away leaving the job unfinished and it has been in extreme heat and sunlight for 3 months – Do we need to re-apply a stripper or re-clean it again before continuing to stain it? Also, apart from stripping, cleaning and staining it, are there any other steps we should be doing as well? (Water proofing, uv protection etc…?) Sorry, we are not very handy in this area but want to try it ourselves…

    Thank you

  17. doug says:

    We have a cedar deck we sealed 2 summers ago. we are wondering if we need to clean it with a stripper first and then a cleaner before we add a new coat of sealant? It has never been stained, just sealed. The paint company we use wants us to buy 3 different cleaners for it…

  18. Ashley says:

    I applied Armstrong Clark Mahogany to our PT deck on Saturday. I finished up with an hour or two of daylight (which only cast shadows on the deck). Sunday was gloomy and rained around 1pm. It was a light rain and was on and off all day. I used the leaf blower to get rid of any standing water or beaded water Sunday evening. It lightly rained on and off Monday until 1pm. Its supposed to be sunny for the next couple days. Do you think the stain will be ok? What should I look for?

  19. Van G says:

    4 yr old cedar deck had Australian Timber Oil on it first time but it didn't last long. Deck is now grey and rough.

    If I want to sand the deck smooth again, should I clean it first (allow to dry), sand with 60 or 80, then seal?

    Thinking of using TWP 1500 – we're in Ontario with full sun.

    • Van G, clean first and sand with 60 grit. When done apply a wood brightener and heavily rinse to remove sand dust. TWP is not compliant for the VOC laws of Canada. Look at Armstrong Clark or Defy Extreme.

      • Van G says:

        We'll see if I can clean tomorrow, dry for a day, sand and brighten same day, then two days to dry and apply.

        I'm in NY state regularly – is TWP 1500 a better product than the others?

        From what I've read you like the AC Deck restore kit?

        I see Messmers in the local wood shops so I assume this is used a fair amount. Wasn't impressed with Cabot's ATO.

        • Messmers makes a decent stain but we do like TWP better. Yes we like the Restore Kits.

          • Van G says:

            I think this is my last week to get something on so I need to go local (Toronto). Will use Cleaner & Brightner from big box (HD or Lowes) and sand as you've suggested. I've got a 1/2 gallon of the ATO left over so I'll put that on to protect for the winter/spring and then do it proplery with Restore a Deck and TWP 1500 in June next year. Thanks for your help.

          • Van G says:

            I should have prefaced that I'm unable to buy any of the products you recommend locally and will have to order online and/or pick up state side.

            Cheers.

  20. Jonathan says:

    I've sanded my deck and am ready to stain, but our weather has been very foggy in the mornings, so I'm concerned the wood hasn't been able to sufficiently dry. Any advice? Should I cover the deck with plastic at night?

  21. Jake says:

    I just sanded a 90 yr old painted porch floor down to bare wood. I believe it's either southern yellow pine or fir. I'm no expert on prep and want to do it properly – but also I'm under a bit of a time crunch in Northern New England with cold weather approaching. My question – do I Have to use a wood cleaner first before a brightener and then stain? Can I skip the cleaner since I'm down to bare wood or no? I used a lower grit to open up the pores. Also I ended up with Penofin Blue (after reading this site) and Penofin Brightener but they didn't have their cleaner product – so I want to be sure I get a good cleaner if I need it to do the job properly or I'll happily skip that step if my case warrants it – please advise! Thanks!

  22. Flyitall says:

    I have a 3 year old IPE deck in Arizona at high altitude, 8500', it gets a lot of UV! I love the natural color and grain and have been using IPE oil to preserve it since I can re-apply every 2 years without stripping, just clean, dry, and re-coat. Is this a good approach? Also, I have a few pine trees nearby and I get some pine sap occasionally that I want to clean off. Any thoughts on cleaning off the sap?

  23. Webster says:

    i have a large PT deck which gets direct sun. it was treated (cleaned) and water sealed 3 yrs ago. w Thompson clear water seal. Now I want to try it myself. Can I clean it w a TSP/Bleach mix? All the cleaners in the big box stores have Sodium Hypochlorite (Bleach) or Sodium Hypochlorite (Bleach) w TSP as the active ingredient (s). I also have a 1900 PSI electric power washer. My goal is to remove the "blacking" and seal the deck from water, and protect the boards. Am I on the right track?

  24. Alex says:

    I was wondering if I had to wait for the wood to dry before applying the brighter after the cleaner? Also, what is the maximum amount of time you would recommend waiting to stain after cleaning/brightening?

  25. Sherry says:

    I am prepping to first time stain a new 9 month old PTW deck. The lower part is only inches from ground level and next to 7 month old sod. Is there a simple way to clean the wood that encloses the area between deck surface and the ground other than lifting the sod during the process? Also, is applying a wood brightener necessary after the cleaning process for new wood?

  26. Gord says:

    I have a 5 year old cedar deck which gets considerable sun. It has not been stained. I cleaned, lightly power washed, and sanded every square inch, then used oxalic acid brightener. The wood looks great except there still are areas which show some grey around knots, and on boards in general. I tried to sand some of those areas again, but the grey persists. I am going to use Messmers stain, based on your recomendations, because it is available in Canada, and your other favorites are not. I am guessing that the numerous small grey areas will show considerably through the stain, Can you recomend a solution. I have spent 5 hard days of prep, on over a 1000 sq ft of surface area, and really want to get it right, even if I need to spend another day or 2 on it before, staining. Thanks for any help. Your site has been my go to for product, and prep information, and thanks for that too.

    • If the gray does not show when wet with water than most likely it will not show when stained.

      • Gord says:

        We had rain for the last couple days, and the grey does show some in some of the areas, in others it doesn't. I have to admit I am a bit frustrated, considering the effort I put in, but I know a few more hours now could make all the difference, when it comes to the final product, and maintaining later. Any ideas?

        I have also done quite a bit of reading on mold, mildewcide type additives, like Krud Kutter mc2 for paint and stain, do you have any thoughts about these? I have a few areas which did show mildew.

        On a side note, I am well aware of the time and effort needed to answer questions, and provide the in depth information you have here, and to do so without the benefit of advertising is amazing. I hope the many who visit this site understand.

        • Gord, it is normal for knots to be lighter in color sometimes ad darker in color. They are not always a darker color. The only thing you could try is to wash the wood one more time. Try Wet and Forget product for the mold.

  27. Gord says:

    Thanks I will re wash, and re brighten, and see if i can find Wet and Forget here.

  28. Bonnie says:

    Hi. We have a PTW cedar tone deck that was built about 2 years ago and needs staining. The cedar tone has come off on some areas of the deck floor and rails. This will be the first staining. What products should we use for cleaning/brightening and will it remove the rest of the cedar tone on the PTW? We live in Manitoba Canada and our deck faces east and about 1/3 of the deck is covered. What type of stain should we use that will need the least Maintenance? Thank you!

    • Bonnie, use the Restore A Deck Stain Stripper and pressure washing to help prep and remove the rest of the stain. Use the brightener when done. Stain with a oil based penetrating stain that allows for easier reapplication in the future.

      • Gord says:

        Hi Bonnie, I live in Edmonton, If I lived close to the border as you may, I would go across and buy TWP, or Defy. After doing much research and based on reviews here I am going to use Messmers UV plus, and after talking to Messmers I am going to slightly darken the cedar tone by measuring in a small portion of one of the darker tints.

  29. Jeff says:

    I've just finished with the restore a deck stripper to remove a water proofer that was applied 2 years ago. I have the brightener that I plan to use next but I have a lot fuzz that I assume needs to be sanded before staining. Should this be sanded before the brightener or after?

  30. Dave says:

    I replaced some rotted boards, stripped (RAD), brightened(RAD) and lightly sanded my entire deck 2 months ago. I waited the 2 months to let the new boards age before I stain with Amrstrong semi-solid. In the meantime the deck has grayed (oxidized). Yesterday I tried a behr all-in-one cleaner/brightener (lightly brushed & power washed) to remove the gray, but the gray is still there. Do I need a more powerful cleaner/brightener like RAD again or is it okay to stain? I've cleaned it twice already, any suggestions?

  31. Tanya says:

    I just finished pressure-washing the old (20+ yrs old) deck. It turned from black to a nice wood color, but still grayish… I don't know what type of wood it is. Most boards are in good shape, very few are warped. I'm planning to sand it a bit, and then stain with Armstrong Clark semi-transparent Cedar.
    My question is: should I sand first, then clean with RAD, then brighten? Or RAD first, then sanding, then brightening?
    Should I power wash in between?
    Thanks!

  32. Tanya says:

    What's the maximum delay between cleaning with Restore-A-Deck and brightening? If I cannot brighten immediately after the cleaning, can it be done in a few days? Or next weekend?
    Also should I wash (or just mist) the deck immediately before brightening?

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