I'm in the process of doing my bathtub walls and I'm thinking of using Denshield™ boards. My total area is 55 sq ft. I found 4'x8' Denshield™ sheets so I will need to buy two sheets to cover my area (32+32=64 sq ft). I will end up with having two seams at the top of the shower that will later be covered by the tile (see image).

The manufacturer says that there is no need to use a liquid membrane (like Redgard). Instead, I just screw them down with corrosion resistant screws, tape and thin set the seams, then use 100% water-proof silicon caulk in the corner seams. They said that it's guaranteed to last for a long time.

My concern:

  1. Are Denshield™ boards better than cement boards?
  2. Is it a good plan to have only one seam in the middle area at the height of 4' from the tub deck and one seam in the right area also at the height of 4'?

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  • Double quotes are for inches. Single quotes are for feet. I assume this is a human-sized bathroom :)
    – Matthew
    May 27, 2020 at 3:28
  • the word is seam
    – jsotola
    May 27, 2020 at 3:31
  • Top tip: wear gloves handling/cutting DensShield. May 27, 2020 at 13:34

3 Answers 3


Whether one product is "better" than another is really subjective. What I can tell you is that denshield is a more advanced product, eliminates the need for a membrane, and I find it easier to use than cement board for sure

However, I would get four sheets instead of three. Then you only need to have three vertical seams, total: two corners and one along a stud. Vertical seams in sheet goods are objectively better. They will be better supported, and you'll have minimal seams (as that seems to be the likely concern).

Plus, with no horizontal seam you don't need to be concerned that water can run laterally and seep through a poor seam.

  • Thanks for the corrections & the advise, so I mentioned 2 sheets as I can use all of them without wasting any, I will end up with installing 5 pieces(it will be less expense) one full sheet under the shower head (left), two pieces in the middle (one 1'x5' on the top) and one in the lower area (4'x5') ,two pieces in the right side (one 1'x3' top) and one lower side (3'x4') water dont reach this side. And I made the seam horizontally on top as it will be far from water reach also),for better covering the seams, i can use waterproof silicone between the seams and then cover it by tape & thin set
    – Chad
    May 27, 2020 at 5:18
  • I also will use the water proof silicon caulk in the corners..make sense? Or this is bad way.
    – Chad
    May 27, 2020 at 5:19

I use Denshield on every shower i do.

I understand the manufacturers recommendations but i think it is good practice to go the extra mile and use a waterproofing membrane on all seams and screw heads. It costs relatively little and it makes it much less likely that a seam or screw head will allow water through.

When butting two pieces together i put 100% mold resistant silicone on the butt ends, i silicone the corner after it is installed. I then fiber mesh tape the seams and apply at least two coats of a waterproof membrane with a brush. I also do this for the seams where the Denshield meets the drywall at the edge of the surround, you want to make sure your seam and its membrane is inside the last row of tile so it is completely concealed by tile.

I also cover every screw heads, it easy to drive the screw a little to far in thereby compromising the skin of the Denshield so i just feel better doing them all, just in case.

If the seams are sealed properly then it does not matter where they are placed but i do tend to put them at the top as water is less likely to be getting up high.

  • Thanks Alaska man..im not sure what is the butt end and I'm confused in one thing only.please correct me if im wrong, so 1. i cover all the seams where 2 boards meets together (also the seams with the drywall) and also the corners seams with cilicone caulk (I have the GE supreme non paintable 100% water proof silicone mold free) 2. Which I'm confused,do shall I use the mesh tape over the seams and put then set on it and after that to paint 2 coats of Redgard? Or just put the tape and then pain it the redgard on top of it (without using the thin set)? Please advise.
    – Chad
    May 27, 2020 at 18:51
  • The silicone on the but joints is overkill, you can omit it if you use the redguard on the seams. In the corner the 100% silicone is doing the waterproofing, now i think about it the redguard will not adhere to it, use one or the other. The GE caulk is correct. I use the redguard for the seams, no thin-set. Mesh tape then redguard. Yes ALL seams get mesh tape and redguard. I put silicone on the edge of all panels that but together and wipe off the squeeze out with a rag and denatured alcohol but like i said it is overkill. As long as ALL seams are taped and redguarded you will be good.
    – Alaska Man
    May 27, 2020 at 19:30
  • Can you explain please how is the but joints is overkill,I'm confused and worried now, as the but joints should be at the same level and if I put silicon and used my finger it will be pushed inside the seam and it will be leveled as if it's one sheet.what I'm missing in here?
    – Chad
    May 28, 2020 at 2:32
  • Last question please regarding the sealant and waterproof membrane. Would it be Ok just to use the 100% waterproof silicone caulk between the seems and using the mesh tape on top and use again the silicon instead of the waterproof membrane (ex redgaurd), since the silicone is 100% waterproof.would this be Ok (why I'm asking and wondering) is beacuse the redgard is too expensive.
    – Chad
    Jun 5, 2020 at 14:09

Waterproofing a shower is for naught. Shower pans/floors need to be waterproof, not walls. STANDING/POOLING WATER is what causes problems. Water does not stay on horizontal walls. A topical membrane on the shower pan and running up the walls about 6 inches or so is all your ever need. I'm an old timer, we never had any kind of waterproofing membrane in my day... just concrete board and Hardiebacker, nailed to studs, taped and tiled. That's it for walls. The shower walls in my house were done almost 20 years ago. I just gutted the whole bathroom, the wife wants to remodel. Nothing but backer board on the walls and not so much of a hint of moisture behind the showers walls I just ripped out a few days ago. No water under the mud pan at the shower liner either.

  • Did you mean to say "vertical walls"? Jul 28, 2020 at 1:46
  • Just because your shower was not done with walls that have a waterproof barrier does not mean that it is not good practice. I have seen plenty of showers built like yours that did have water damage in the structure behind the non waterproof grout,cement board. It is worth the added expense to insure if there is a problem with the tile/grout that water will not get into wall cavity.
    – Alaska Man
    Jul 28, 2020 at 18:57

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