limestone shower benchI get a LOT of questions about how to build and waterproof a bench in your shower. I’ll touch on the easiest method here, but there are a couple of different methods you can use.

I will describe simple framing of a bench with your substrate over it. You can also use after-market, pre-fabricated benches. Better Benches (google it) attach directly to your wall substrate, the top gets filled with deck mud and it gets tile. There are also several different Styrofoam products available from companies like Schluter and Laticrete. They are made from the same type of foam used for their shower bases. Although they are ‘foam’, once tiled they are more than sturdy enough to support your tile.

While you ‘can’ build a bench in your shower after you form the shower floor with deck mud, it’s always easier to make your bench first. Your floor substrate is flat, your shower floor (should be) sloped. It’s difficult to build a level bench on a sloped floor.

But you can do it if you wanna.

Rectangular frame for shower bench

Rectangular frame for shower bench

As I said typed, the easiest way is to simply frame a bench and cover it with your substrate. The waterproofing is ALWAYS easier if you use a topical membrane. Either a liquid like Hydroban or redgard, a sheet membrane such as kerdi, or a topical board like kerdi-board.

If you are using traditional waterproofing in your shower with a membrane behind your substrate, I will cover that in a little bit.

Triangular frame for shower bench

Triangular frame for shower bench

The rules for benches and concrete are the same as curbs and concrete. If you are building on top of concrete rather than wood use bricks (cinder blocks) to build your bench. Just stack them up to the height you need and bond them to one another with regular thinset.

There is no hard and fast rule to framing your bench. Just build a square frame box out of 2×4’s and put your substrate (cement board, or drywall if you’re using kerdi) around it. It’s really that easy. If you want to build a corner bench then build a triangular frame, or arced frame, to place in the corner.

Arced shower bench

Arced shower bench

The first couple of photos are small bench frames I made for showers. The top one is only 2 ½ feet wide by 1 foot deep. It is 22” high. I normally build them 21 or 22 inches high, but that isn’t required either. The other two are corner benches.

 

 

 

 

 

Slope the top of your bench!

Slope the top of your bench!

Be sure you slope the top of your bench ¼” per foot toward the front of the bench! Water needs to drain off of it rather than collecting in the back of it.

So how do you decide how high to build it? Ask the woman in the house. I’ll let you guys in on a little secret. The bench she wants you to build in the shower? She’s not going to sit on it. She wants it so she can shave her legs. Really. Ask her.

So it really depends on how tall she is and where the comfortable height is for her. Ask her. Starting to see a theme here?

It usually looks better if you build the bench around the size of your tile. For instance, if you have 12” tiles, don’t build your bench 25” high because you’ll have a 1” strip at the bottom. It’s not imperative to get it exactly the size you need it, but keep the tile size in mind while building it.

Kerdi waterproofed bench

Kerdi waterproofed bench

Your bench doesn’t need to be huge. It can even be just a little triangle in the corner, like the one above. It’s for a foot, not a butt.

Once you get it framed and covered with your substrate just waterproof it with your choice of topical membrane. This one is kerdi.

 

 

Kerdi-board waterproofed bench

Kerdi-board waterproofed bench

And this one is kerdi-board.

I don’t have any photos of a cinder block bench, but it’s just as easy to build one. Stack your cinder blocks up however high you want them, minus 2”, with the open holes vertically.  Once you get them stacked up place cinder block ‘caps’ on top. The caps are solid 8 x 16 x 2 inch bricks that fit right over the top of the cinder blocks to give you a solid top.

Once again, make sure the top of your bench, in this case the caps, are sloped ¼” per foot toward the front of the bench.

Once the thinset cures just cover your cinder block bench with your topical waterproofing.

Now, if you are using a traditional waterproofing method it’s a bit different. You need to build your bench BEFORE you put your membrane up on the walls. I really don’t recommend this method, it’s a pain and if one thing is done incorrectly then your bench may leak. But it can be done.

And I don’t have pictures of that either, because I don’t build them like that anymore. But I will answer any questions you may have about them if you leave a comment below.

Frame your bench against your wall framing and put a solid piece of backerboard on the top, making sure it’s sloped. When you run your membrane down the walls, run it down and over the bench, down to the floor overlapping the front of the floor membrane.

Your regular substrate will be installed on the face of the bench (and the sides, should you have them) but you need to make the top of them 1” higher than the frame. The front of your bench is treated as any of the walls. The floor membrane runs up it and the wall membrane overlaps that with the substrate screwed to the front.

Your substrate will stick up 1” over the top of the frame to form a ‘box’ around the top of your bench. Your seat, the top of the bench, is formed from deck mud. The extra 1” will give you an edge for your top and the top is simply shaved flush with the top of the substrate. Tile is bonded directly to the cured deck mud on top of your bench.

You cannot use your wall substrate on top of your bench! It will drive fasteners through the membrane on a horizontal surface – it will create a problem. You need to use deck mud.

If you are going over concrete and using the traditional method you need to build and waterproof your entire shower, then build your bench INSIDE the shower, so the waterproofing is surrounding your bench. There is no waterproofing on the bench itself, it’s all under and around the bench.

If you build your bench inside the shower it needs to be built out of cinder blocks. You cannot frame a bench inside your shower using wood unless you are using a fully topical waterproofing method in your shower.

This is why it’s better, and easier, to use a topical membrane of some sort for your bench. It is, in my opinion, the only way to build a bench. If you want a bench, spend the money for some sort of topical membrane for it.

If you have a bench you cannot use a topical membrane only on the bench with traditional membrane on the walls. There is no way to channel the water from your membrane behind your wall substrate, over the membrane on the bench, then into the floor membrane (unless your bench is built inside your waterproofed shower).

As I said typed, there are many ways to build a bench for your shower. This is the easiest. I realize some of this may be confusing due to different types of waterproofing and lack of pictures. I only build my benches with topical waterproofing, so I just don’t have them.

The important keys are to ensure that your waterproofing on the wall is continuous from the wall, over the top of the bench, and down the face of it, and to ensure that the top of the bench is sloped toward the drain. Anything wooden needs to have waterproofing OVER it, and the waterproofing needs to tie into both the floor and the wall membranes.

I’m absolutely positive there will be questions, so leave a comment in the comment section below and I’ll answer it as best I can. Not necessarily about this method, either, if you have a question about any of the pre-formed benches, better benches, etc., I’ve used most of them and can answer those as well.

Below are a bunch of photos of different benches. Look through them first, you may discover an answer in there. You can click on any of them for a larger version.

{ 255 comments… add one }

Leave a Comment

  • Jaime

    Got your e-book. Absolutely love the tips. Just the idea of removing sheetrock and tile together saved me hours of work!

    My wife is wondering if the hole inthe bath will ever get fixed :bonk:

    So to keep her happy, (you are right on this one) :-o and give her a bench to shave her legs, I need help.

    Enlarged a 40x 40 shower by removing 12″ bench. (As an aside, the builder had put great tile materials, but whoever put the pan in had preslope uphill to the drain and nailed the pan membrane down – we call that ‘no bueno!’ :guedo: )

    Now I have a linear drain planned in a 52 x 40 shower. – the QUESTION for you : Can I put in a corner bench and have the underside slope back into the corner so that the floor is still square? I would use 2×4 lumber frame, plywood top with sheetrock over plywood and for the triangle face. Then Kerdi membrane. – Sound OK? Will it hold up?

    My marriage is riding on this!

    PS: Coors Light can is perfect for blocking the drain without going down the drain! :dance:

    Thanks!
    Jaime
    Frisco, TX

    Reply
    • Roger

      Hi Jaime,

      Yes, if I understand you correctly, that will work fine. What I would do, however, is actually build the bench as you’ve described then do the floor. Just treat the face of the bench as a fourth wall as far as the floor is concerned.

      Didn’t know that about coors light – I don’t drink that swill. :D

      Reply
  • Scott

    Finished pre slop for new shower. I can tell it did not stick to concrete floor. I did not know to use thin set. I used ore pitch plastic kit. Should I redo or can I add pan liner and final mud bed? Thanks for any help Scott

    Reply
  • Rich

    Roger –

    Have purchased a new home and the shower is complete with tiled walls and floor. What is the best way to go about adding a bench. Should I use instructions above for an unfinished shower ? Should I remove tiles ? What do you recommend ?

    Reply
    • Roger

      Hi Rich,

      You should remove the tile from where you want the bench, build the bench and waterproof it (tying the waterproofing into the existing), then replace the tile in and around the bench.

      Reply
  • Dale

    Roger your tips are great. I have a project in progress on a new house. I have already done the pre slope floor and planning on a small corner bench. Do I build the bench on pre slope and attach to wall then lay down membrane over bench and then pour top coat or do I do top coat then build bench? I am using hardibacker and red guard.

    Reply
    • Roger

      Hi Dale,

      Build the bench first.

      Reply
  • Hollie

    Love your site, working on our master bath….building a bench in the shower with a short wall and glass doors. Took a look at your site for advice for a shower seat. Great advice! Thank you!

    Hollie :evilb:

    Reply
  • Tom

    Hi,
    This continues to be my go to site for anything tile (I owe you many beers at this point).

    I’ve got Kerdi membrane on the walls, and will be using the kerdi pan and their triangle corner bench. Kerdi video shows cutting the pan corner and setting the bench on the floor (and then membrane over everything, as expected). Can I do this instead: build up the pan to wall membrane as if there is no bench, THEN place the foam triangle on top of the membrane? My thinking is that the bench sits on top of the barrier,as precaution against a leak at bench to wall interface. Guess I could also add membrane to bench, but then I’d probably go traditional route. Is this an advantage,or is it just a rookie trying to avoid the more complicated overlap joints?
    Thanks!

    Reply
    • Roger

      Hi Tom,

      Yes, you can, but you still need to cover it with the membrane.

      Reply
  • Nick

    Hey Roger,
    I am rebuilding my master shower and am wanting to build a bench.
    Here is the status.
    Concrete slab.
    Already did 1/4″ slope pre pitch bed
    Then did Oatey pan liner
    Next did moister barrier and Durock backer boards on walls
    I am at the final mud bed layer
    I was planning on doing cinder blocks for the bench, but just read your reasoning behind doing the bench before the slope.
    Unfortunately I’m past that.
    Since I will be installing on a slope, I know the top back of the blocks won’t be flush. What do you recommend for filling that void?
    Deck mud packed behind?

    Thanks
    Nick

    Reply
    • Roger

      Hi Nick,

      Yes, deck mud packed beneath the bottom course to level it, let that cure, then finish building your bench from there.

      Reply
  • Marty

    Hi Roger,
    I have built my shower and bench according to your manual for waterproofing with HydroBan and DuroRock, but have sheet rocked the rest of the bathroom and ceiling. I am planning to tile the full walls and floor. I am not sure how to allow for movement in the following.

    1) The transition between DuroRock and Mold Tough sheetrock
    2) The sheetrock corners of the bathroom
    3) Between the walls and the ceiling
    4) The walls and the floor. The floor has radiant heating thin setted in under the DuroRock.

    Does any sheetrock that is taped and plastered have to be primed before tiling?
    Thanks
    Marty

    Reply
  • rich

    HI I want to build a 2x4bench in a plastic shower base what is the correct steps for putting the wood on the plastic so there will be no give or stress on the plastic that could result in a crack

    Reply
    • Roger

      Hi Rich,

      There are no correct steps for that. You can not build a 2×4 bench inside an acrylic pan.

      Reply
      • Jeff Ward

        Hey…just my two cents…Roger is the REAL expert!!! :D

        You could fasten the bench to the wall…with angled 2×4’s above the pan…and run the cement board down the angled face to meet the pan edge…takes more time and you need to be sure your construction is “rock sturdy” :rockon: …I have done this in several showers…but have always used the Schluter pre-sloped base and membrane…then tile…I, personally, try not to use a pre-made pan unless the customer absolutely insists…Good Luck!

        Jeff

        Reply
  • Cindy

    I am trying to design a neo angle shower. I have a couple questions. Can I buy a prefab shower pan and build a bench on the end? If that’s not a good idea, then I need to make it with a membrane or Redgard. Is Redgard as good as a membrane? I am very much a rookie at all this so bear with me.

    Reply
    • Roger

      Hi Cindy,

      Yes, you can, but you need to ensure the front face of the bench substrate overlaps the flange in the same manner as the walls. Redgard is a membrane, and the correct one for your application.

      Reply
  • Don

    Traditional pan, with redgaurd on walls. Building bench from cement blocks. Do I need to completely fill in the area behind the bench?

    Reply
    • Roger

      Hi Don,

      No you don’t.

      Reply
  • Chris

    Hi Roger,

    I’m remodeling our bathroom and installing a new tiled shower. I plan on building a mud pan and having a bench in the shower. My preference is to use Desshield for the walls and to cover the bench with Hydroban for waterproofing. The side of the bench will not have a kneewall but rather have the glass sit directly on it leaving a couple inches of the bench on the outside of the glass. Here are my questions:

    1) Am I correct in following these basic steps: Repair subfloor and install new drain. Properly stud and block the walls and 2×4 curb. Install new shower valve. Build 2×4 bench. Install tar paper on floor and then mud preslope. Install rubber pan liner. Install top pan. Install Densshield to cover walls and entire bench. Apply Hydroban with fiberglass cloth to all joints, corners, screws and curb. Apply thinset on pan and tile floor. Apply thinset on Densshield and tile walls/curb.

    2) From a tile planning perspective what would you recommend I do when tiling the seat and outside side of my bench to not end up with exposed cut marble tile when looking at it from outside the shower where the seat tile sits on top of the outside wall tile? Bullnose, get a custom finished piece for the bench seat, something else?

    3) I plan on buying your ebooks. Given my plan above which ones do you recommend that I get?

    Great site and love how you mix in the humor!

    Best,
    Chris

    Reply
    • Roger

      Hi Chris,

      1. You didn’t mention it, but with the liner the curb needs to be made with mud, not covered with densshield. I’m sure you know that, but the one time I don’t specify it…. :D

      2. I prefer to bullnose the marble and begin with a full, bullnosed piece down both outside walls and along the outside of the bench. I would bullnose one full piece with two edges and begin with that piece on the top, outside corner of the bench.

      3. This one: Traditionally waterproofed shower floor with topically faced walls

      Reply
  • Amy

    Hi Roger,

    I framed my bench using 2×4’s. I covered it with my shower pan liner, I tried to put deck mud on the top but the liner is not taunt and it sags on the top of the bench. Could I leave the liner down and cover the bench with Kerdi board on the top, front and sides? Could another option be duralock top, front and sides then red guard?

    Reply
    • Roger

      Hi Amy,

      Either option will work just fine.

      Reply
  • Claude

    Roger , I have installed USG dura rock foam square bench with thinset now I want to waterproof it . I have Kerdi membrane on hand and red guard with fiberglass mesh (6″x75ft) which would you suggest for water tight seal. Thank you for help

    Reply
    • Roger

      Hi Claude,

      Redgard would be easier.

      Reply
  • Robert Juric

    When building a bench, or even the rest of the shower for the matter, and using a topical waterproofing method, how far down should I bring the backer board? Does it go to the floor and I put the deck mud against the backer board? Or should I build the deck first, then bring the backer board down to meet it before applying the topical water proof?

    Reply
    • Roger

      Hi Robert,

      When using a topical membrane the backer can go in first with the mud deck against it.

      Reply
  • Amy

    Hi Rodger!

    Love your site. Need help!

    I have built a bench out of 2×4’s on top of the pre sloped mud deck. I have covered the floor and wrapped the bench with the PVC shower floor liner. How do I put a substrate on the bench? I have read that the top of the bench should just be deck mud. What about the front and sides of the bench? Is hardi backer and red guard enough? Also just to be clear the top of the bench should be deck mud only over the shower pan liner?

    Reply
    • Roger

      Hi Amy,

      Yes, it should be deck mud only on the top. The front would be installed just like a regular wall, with backer over the face, then redgard.

      Reply
  • Scott

    Roger,

    First, nice work on the radiator in the photo: Kerdi waterproofed shower bench6372. Seriously though, this resource you have assembled is outrageous. I’m grateful for all of the insights and instructions; the humor is, eh, passable.

    I’m currently working on a new construction shower that was framed with a bench by the builder. The curb extends past the bench like you have in the pic I mentioned. My concern with this design is the potential for a difficult corner to clean if there is a glass panel installed on the curb. I imagine a damp corner that grows darker and danker as you look into it… I’m intending to rebuild the bench flush to the outside of the curb and have the glass come up and over the end of the bench. So the end of the bench will not be in the wet zone. Would you, at your convenience, share your thoughts here? Perhaps after a beer… or 4…

    Thanks,
    Scott

    Reply
    • Roger

      Hi Scott,

      That particular shower had sliding glass doors, so that spot wasn’t trapped behind glass. With fixed glass I would absolutely build it out flush with the outside of the curb and have the glass go over it.

      Passable humor is more than I usually get. Thanks. :D

      Reply
  • MicKay

    Help please! I have followed your advice on several of my own things and they are Great, thanks!
    My son, who lives far away from me, paid good dollars to have a shower in his ensuite. It has a pebble floor, and pebble bench, which look great. The big problem is the bench, not only is it not sloped, it goes down in the middle and a pool of water sits there! I have pictures but don’t see how to attach them? What should the contracted do, rip it out and start again? Or is there a way to repair/save it. Let me know how to send pictures,thanks. :wtf:

    Reply
    • Roger

      Hi MicKay,

      If it is pooling water it needs to be removed and rebuild with a proper slope. You can upload photos here.

      Reply
  • Garth

    On suggestion, I set my preslope before my bench. ( this is on a down to studs, and subfloor remodel) I had planned on doing treated 2×4 construction of my bench. I gather from reading that I need build my empty shower( liner, bed, and wallboard) first and then build the bench from the point I’m at. Do I let my bench base float at this point? Had I framed it before I did the preslope I would have secured the base to the subfloor. Driving nails through the pvc liner wouldn’t be good. Can I still do the framed construction without worry of potential flexing of the bench, because the base isn’t tied in?

    Reply
    • Roger

      Hi Garth,

      If you’re building it inside your shower liner you need to build it out of cinder blocks or bricks, you don’t want ANY wood inside your liner.

      Reply
  • Jeff

    Hi Roger, I have another question. I got the kerdi pan embedded in the mordor in the shower. 8 hours later when I step on the pan in some places I can feel it move. It’s not much movement but it makes me wonder what this cause problems?

    Reply
    • Roger

      Hi Jeff,

      You’re stepping on it before the thinset if fully cured. Or you don’t have complete coverage. Or both. Did you get complete coverage?

      Reply
  • Tara

    Hi Roger, I just want to make sure I understand. We have a concrete slab in our basement bathroom. So we should build up cinder blocks and use the topper. At that point should we still use the mud mix on top ? or is the thinset filling the seams good enough? If we don’t need the mud mix on top, what is the best way to slope the cinder block toppers? we have a topical water proofer but also the liner to put over the preslope, do we really need to use the liner if we have the paintable water proofer and if not do we still need to do a preslope and then another layer of mud mix to complete the shower pan?

    Thanks in advance for your help!!! I will have more questions about framing and using hardi backer (to which I think I know the answer)… but I don’t want to overwhelm you by posting all the questions here.

    Tara

    Reply
    • Roger

      Hi Tara,

      You need to decide on your waterproofing method for your shower floor before anything else. If you want to use a liner then yes, you need both slopes and mud on top of your curb (to cover the liner). If you want to use topical waterproofing you don’t need the mud on top of the curb and you only need a single slope, but you do need to either use a bonded waterproofing (topical) drain or use the divot method.

      Reply
    • Roger

      Hi Tara,

      You need to first decide how you’re going to waterproof your floor. If you use the liquid you only need one layer, but you do need a topical drain or the divot method. I don’t know what you mean by using mud mix on top (I know what that means) OR is the thinset filling the seams good enough? Do you mean the seams of the blocks? If so, it depends on your waterproofing method. You need to figure that out before anything else.

      Reply
  • Justin

    I already have my preslope in and want to build a shower bench.

    If I go the 2×4 route do I frame it in now and cover it with my PVC liner and then do my top pan?

    Or do I lay my PVC liner first and frame it in

    Reply
    • Roger

      Hi Justin,

      If you use 2×4’s you need to frame it first and put the liner over it.

      Reply
      • Justin

        thanks roger,

        so i put the liner over preslope and bench

        build top pan

        CBU walls and bench and then redgard walls and bench

        sound about right?

        Reply
  • Kelly

    Roger,

    I’m going to quote a couple paragraphs from this article and then ask what I hope does not turn out to be a stupid a question……

    “While you ‘can’ build a bench in your shower after you form the shower floor with deck mud, it’s always easier to make your bench first. Your floor substrate is flat, your shower floor (should be) sloped. It’s difficult to build a level bench on a sloped floor.”

    “Be sure you slope the top of your bench ¼” per foot toward the front of the bench! Water needs to drain off of it rather than collecting in the back of it.”

    So here is the question – if the bench top has to be sloped 1/4″ per foot and the floor has to be sloped the exact same amount, why would I want to build my bench on the level substrate and then go to the extra trouble of building a slope on the top? Why not just form the shower floor and then put the bench on top? The slope in the floor will provide the necessary slope for the bench top.

    Oh yeah, I almost forgot – I have another question. If I use the topical method of waterproofing the shower, do I still need to use the thick rubber liner on the floor before I lay in the deck mud and build the floor? Or can I just build the floor with deck mud and then waterproof it with something like Redgard? I’m actually using TEC Skill Set Waterproofing and Crack Prevention Membrane – its what Lowe’s sells (5 miles from my house) and is supposed to be the same thing as Redgard which is sold at Home Depot (30 miles from my house).

    By the way, I am building a shower on a concrete slab floor and using Hardiebacker boards on the walls and cinder blocks for the bench.

    Reply
    • Kelly

      Ummmm…..never mind. I just realized that if I do that, while the top will indeed have the correct slope, the whole thing would be canted forward and back of the bench will not be flush against the wall.

      Disregard last transmission, over.

      In fact, feel free to delete this entire post from your web page.

      Now I need more beer. :bonk:

      Reply
      • Roger

        Hi Kelly,

        Umm, okay. :D But you’re correct! Unfortunately all my questions show up in the order they were received – like a horrible tech support line. And we’re nearly as organized as that, too.

        Reply
    • Roger

      Hi Kelly,

      You would not do that because if your bench is 18″ high the back of your bench will be against the wall on the bottom and about 1/2″ away from the wall on the top. Think about putting a bookshelf against a wall then putting 1/4″ boards beneath the back of the shelf at the bottom, the top of the bookshelf will be away from the wall and it will not sit level or straight.

      You can just do a single deck mud and seal it with the tec.

      Reply
  • Ramon

    Roger,
    I am in the middle of a double bathroom project…one a shower stall and the other a full bath with tub. My question concerns the shower area. I will be using a pre-fab pan(NOT my decision) and subway tile with a direct set bullnose up both sides to the ceiling and frameless shower door / wall on two open sides. 1.) Should I bring my bullnose beyond the face of the pan and down the front of it and if so how would you blend that with the grey base bullnose that will be on the floor job? 2.) should I start my subway tile from both outer edges of the shower and work into the corner? Your advice will be GREATLY appreciated!!! Thanks…Ramon

    Reply
    • Roger

      Hi Ramon,

      Normally you would take the floor bullnose all the way to the curb of the pan, then stack the shower bullnose on top of it. The inside edge of the bullnose should line up with the outside edge of the curb, so your tile extends the width of the bullnose past your curb. Yes, you should start your subway tile at the outer edge of the shower and work into the corner.

      Reply
  • Bob

    Hi Roger,
    I am building a bench and I want the depth of the seat to be exactly the width of one 12″ tile. So for framing the seat I need to subtract the thickness of the layers on the vertical sides: backboard (1/2″ drywall) , the thinset for the Kerdi, the Kerdi membrane, the tile thinset and the tile depth. How thick will the 2 layers of thinset be? I don’t want to have to cut a small amount off of the tile and I really don’t want to be slightly wider than the tile – ideally it would be a perfect fit. How do you suggest that I calculate this?

    Reply
    • Steve in Denver

      Roger will undoubtedly have a better answer, but I figured I’d throw in my amateur 2 cents.

      1. If the front vertical surface (below and in front of the seat) will receive the same stuff (kerdi, tile, etc) as the back vertical surface (behind and above the seat) then the thickness of each will be appx the same and therefore cancel each other out. In other words, frame the seat for the size of your tile.

      2. When I have done similar things I tucked the seat tile under the wall tile giving a margin for error appx equal to the thickness of the tile. Also consider that the wall/seat joint will get caulk (100% silicone) which can conceal slight variations.

      3. Measure your 12 inch tile to see how wide it actually is. My 12″ tile is 11-3/4″, for example.

      4. Don’t forget to frame the bench so your seat slopes a minimum of 1/4″ per foot in the direction of the drain.

      Maybe that was more than 2 cents worth of input. :)

      Reply
      • Bob

        Thanks for the input. My bench is at the end of a corner shower so there is tile on both the front and back of the bench. So each side will be around 7/8″ with the drywall, thinset and tile. I want the tile on the top of the bench to cover the edges of the vertical tile, so the depth of the bench framing will need to be about 10 1/4″: 12″ tile – 7/8″ front – 7/8″ back. I just don’t want to miscalculate and end up slightly over or under 12″.

        Reply
      • Roger

        Actually, Steve’s answer is better than mine. :D (I need beer…)

        Reply
    • Roger

      Hi Bob,

      You do it exactly to the size of the tile without worrying about the kerdi and thinset. The amount that you’ll have building up the front of the bench will be the exact same amount on the wall behind the bench, so it’ll still be exactly the size of the tile. Kerdi with thinset will be about 1/16″ thick, the thinset behind the tile will depend on what size trowel you use.

      Reply