Asked on Oct 08, 2015

How do I waterproof a wooden shower?

Gramma Birdie
by Gramma Birdie
I'm making a man-cave bathroom. I want to line the shower with wood, most likely boards from wooden pallets. I know I need the cement type of drywall. Do I need a liner? I will lightly sand the boards, but how do I waterproof the boards and prevent water from seeping between them? Do I waterproof the boards on all sides before mounting them? Or just the facing surface once they are in place? Do I caulk or glue between them? I'd like them to look just like a wall. The pic is of the gutted bathroom. Shower will be walk-in, 30" x 5'.
  20 answers
  • Gramma Birdie Gramma Birdie on Oct 08, 2015
    Below is the photo.
  • Deborah Deborah on Oct 08, 2015
    Affix to walls using mastic, butting boards right up to each other. When dry give several coats of bartop or marine varnish.
    • Gramma Birdie Gramma Birdie on Oct 08, 2015
      @Deborah Thanks for the reply. This is what I had assumed would be the process, but then I read the info from Danielle, and that is a more daunting process, although I can see the benefit of that process. Hmmm. Maybe I should just use corrugated sheet metal from grain bins. Ha.
  • Danielle Danielle on Oct 08, 2015
    Wow, you haven't decided to go the easy route, have you? Quite frankly there are a lot of risks for leaks in what you want to do and I would not tackle this as a DIY unless you've got access to a LOT of expert help. Are you wanting to do the wood on the bottom as well? If so that's a whole other kettle of fish with getting enough of a grade for the drain to function properly. I would really recommend that you start with reading this article: After that you could mount the boards to the wall using a non water soluble adhesive, and run a tiny bead of clear caulk between each seam, then fill with a good quality wood filler. Then after that is fully cured (several days) a light sanding and start with the multiple coats of marine varnish you will have to use to get a good seal. To truly make this waterproof and safe you'll pretty much want to treat this like you would a wooden boat, and that means at least 12-15 coats of varnish sanding with around a 1,000 grit paper in between each one. And be prepared to renew by sanding and adding a couple coats every few years. My father in law restores antique wood boats so trust I am not exaggerating with this. We KNOW what it takes to make something safely waterproof, and doing this inside a house is no joke.
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    • Gramma Birdie Gramma Birdie on Oct 09, 2015
      Thanks for the helpful words, Danielle, including the nautical pun! Good idea about the broomed cement.
  • Janet Pizaro Janet Pizaro on Oct 08, 2015
    The idea sounds very different.however in researching the process it sounds like it will be alot more work than anticipated.My advice I would do some more seeking on this remodel
    • Gramma Birdie Gramma Birdie on Oct 08, 2015
      @Janet Pizaro Yes, I'm still in the research mode. I really hope to be able to do this, but if I can't, I'll probably line it with grain bin corrugated sheets, or similar.
  • Janet Pizaro Janet Pizaro on Oct 08, 2015
    sorry that is just my opinion.
  • Dallas Sills Dallas Sills on Oct 09, 2015
    There are some very good tiles for bathrooms that look like wooden planks. I'd seriously look into them to see if that is an effect you'd like.
    • Gramma Birdie Gramma Birdie on Oct 09, 2015
      @Dallas Sills Yes, I've seen them, too. It is an option but my first choice is the real wood. But then, not sure it will be possible/practical.
  • Jonnie Hammon Jonnie Hammon on Oct 09, 2015
    You can use a deck sealer, I would do multiple coats, the caulking is another protection if you don't want to sell all sides of the wood. Remember it will have to be resealed every year. I like Thompson's sealer.
  • Joanie Joanie on Oct 09, 2015
    Check with your local boat shop. There are marine grade sealers that might work for this project. These might also last a little longer than say Thompson's or another deck type sealer.
  • Richard Perry Richard Perry on Oct 09, 2015
    Teak wood is what you need! It can take the water without rotting! Just rub it down with teak oil every now and then!
    • Gramma Birdie Gramma Birdie on Oct 09, 2015
      @Richard Perry Well, that's something I didn't know at all. So, teak doesn't have to be sealed?
  • Jack Carter Jack Carter on Oct 09, 2015
    Richard Perry is right on the money, However, teak is expensive and may not be something you can use. If you're dead-set on doing this project, consider the following: Use the proper backing (cement board, etc); plane all four edges of each board to ensure they fit properly. If you have the tools and time, consider tongue/groove; as Joanie suggested, use a marine-grade sealant. Finally - keep a close eye on the floor/walls to ensure there are no leaks and be sure to reseal frequently. The ultimate reality may be that this is one of those ideas that are better pondered than practiced.
    • Gramma Birdie Gramma Birdie on Oct 09, 2015
      @Jack Carter Ha. True, Jack. Better pondered than practiced. Yet, I'm not completely done pondering...
  • Barbara Butters Barbara Butters on Oct 09, 2015
    There is a lacquer that is used in building boats that is waterproof , perhaps that would,be a good option
  • Ray Phillips Ray Phillips on Oct 09, 2015
    As a retired builder " mostly tired" I agree with Jack, plane the boards on all sides for a tight fit As you put them up use a silicone caulk between the boards, then after you have them all up put at least 3 coats of "spar varnish" allowing 24 hours between coats and lightly sand between coats.. Spar varnish is made for marine use. That should do what you want. Hope this helps.
    • See 1 previous
    • Z Z on Oct 09, 2015
      @Gramma Birdie, the purpose for sanding it between coats is anytime you get wood wet it raises the grain, causing nubs. The sanding knocks them down so you'll have a smooth finish.
  • Maggie Kimble-Bernard Maggie Kimble-Bernard on Oct 09, 2015
    Marine varnish.
  • Barbara Christensen Barbara Christensen on Oct 09, 2015
    But keep in mind, even with marine varnish. the boards may require sanding and more coats somewhere down the line. I know because I turned an antique oak buffet into a bathroom vanity and used the varnish to protect the wood from water splashes and young drippy fingers. That said, I did the original project in 2002 and it held up well for 10 years before more work was needed.
    • Gramma Birdie Gramma Birdie on Oct 09, 2015
      @Barbara Christensen It's great to know the vanity held up against young drippy fingers. I wouldn't mind recoating the shower every couple of years, if it looks good enough to keep in the first place. This shower will likely be used only a few times a year.
  • Judyms9 Judyms9 on Oct 09, 2015
    What about using laminate woodgrain flooring rather than wooden panels which will warp over time because of dampness? (I think someone on this site did a wall covering that way, and it looked good.) You would still need to clear caulk, especially the bottom half of the shower area.
    • Marie Alesi Caruana Marie Alesi Caruana on Oct 09, 2015
      @Judyms9 Laminate flooring cannot get wet because of the backing. Once it gets wet it swells and bubbles--take it from one who knows what a leaky dishwasher did to my laminate floor. Wood is the better solution by far.
  • Dee Dee on Oct 09, 2015
    Spar varnish or marine at least 3 coats. Shermen Williams outdoor varnish.
  • Bev Deardurff Bev Deardurff on Oct 10, 2015
    This idea is quite different. I was a Girl Scout. When I "bridged" over into Senoirs, our troop focused on pioneer lifestyle. We we at an "en-actment" and I noticed that some of the "period" people were carrying wooden canteens. I found the vendor who was selling the kits. I purchased one and assembled it. In order for my wooden canteen to hold water, I poured hot, melted parafin into it, and rolled it in all directions in order for the parafin ti cover the total inside of the canteen. I let the parafin cool and harden. It has been a few years, 35 yrs, but I don't remember it leaking. I don't know how or if you could apply it as waterproofing wood for a shower. You probably couldn't take a hot, steamy shower. This idea is way out there! But it's another option.
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    • Gramma Birdie Gramma Birdie on Oct 10, 2015
      Thank you all so very much! I've learned a great deal about melding wood, water, and waterproofing. I have many other projects where I can put this info to good use, yet I decided to go another route with the shower. The reason for the change is because it would be a lot of work to make it work and then I wouldn't know until too late if it wouldn't work. Instead, for the shower area (which is completely open on one long side so it is handicap accessible and because it looks cool) I am going to cover the walls with huge mirror pieces that I'm getting from the local Habitat for Humanity's ReStore store. The wall opposite the shower will be old barnwood (waterproofed, but in a much less precarious place) and it will reflect into the shower mirror. Not only will the shower appear even bigger, but it will still look like wood! I have a curved shower curtain rod and am going to put a shower curtain with big trees on it. If I have to make it, I'll use fabric with a clear liner. When closed, that will reflect in the mirror letting the showeree shower in-the-forest. Oh, there is so much more to this bathroom, but I don't know how much I can print here. You can look up some of my crazy antics from starting the rest of the basement on my FB page (Virginia Gregg). Look for the "Remodeling Saga" posts. (I finally quit them because it was taking too much time.)
  • DC DC on Oct 11, 2015
    I made my shower ceiling out of cedar wood that was made to line closets. (You can buy it at the big box stores.) I stained each piece a little bit different color (but similar) by mixing small amounts of stain together. I also used the rough side of the wood to have it look more rustic. The wood came in a package and was tongue and groove; so there was no space between the planks. I then applied 2 coats of polyurethane and attached it to a piece of plywood. It turned out awesome! That was four years ago and even with the steam from my still looks the issues from water. (I will try to send you a photo tomorrow.....for some reason I can't get my photo to upload right now.) One wall in my bathroom and on the outside of my shower is also tongue & groove cedar. The wall part is actual boards. My shower boards are thin. Cedar is more naturally waterproof. With shower walls, I would still use some type of sealer, though. Either the poly or I have heard the marine varnish mentioned above is great. Just cedar for thought! :)
  • DC DC on Oct 11, 2015
    Ok, here's a photo of my shower ceiling before it was placed in the shower. Stained & sealed. (The planks are rather bland - not much color - until stained.)
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    • Trina Lowe Trina Lowe on Dec 14, 2020

      thank you for posting your adventure! I'm considering the same application with the wood on the ceiling of our shower and came across the cedar/closet pieces this weekend and was pondering them... thought they'd be too thin and was going to look elsewhere, so the fact that you've used them successfully makes me really happy for you and me! anyway... did you use any plastic behind them? i'd rather not use the plastic and let the steam work through wood, insulation, then out my vented ceiling. just wondering.

  • Fiberglass resin coating all of the installed planks after stain and between filling all gaps ..... Kinda funny noone suggested this because it's probably the number one waterproofing agent used in marine construction