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Shower Waterproofing Crash Course

4 Shower Waterproofing systems for tile showers

Shower waterproofing systems
4 Different Shower Waterproofing Methods

Waterproofing a shower. This seems like common sense, doesn’t it? Well, a lot of showers that are built these days still have no shower waterproofing whatsoever. Or they have poor or improper waterproofing.


What! No Waterproofing!?

How can this be? Well, I think there are multiple parties to blame.

For starters, the companies that manufacturer tile backer board deserve some blame. Many times they are vague on whether shower waterproofing is required, or not.

Is Hardibacker and Durock cement board waterproof?

Also, home builders, remodelers, and homeowners that focus too intently on the price and go with whoever is the cheapest rather than paying for a properly built shower.

Tile installers lacking proper training and education would be another cause. They just do as they’ve been taught. Maybe sometimes they reason it out themselves and decide waterproofing a shower isn’t necessary. A common  line of thinking is: “I’ve been doing it this way for “X” amount of years and never had a problem.”

Lastly, a lack of enforcement by local inspectors. Most local building codes require some sort of moisture barrier and oftentimes this is overlooked.

The original five posts on my blog were combined into this one new, updated, and snazzy post. If you’ve been redirected here from another post then now you know why. 🙂

At any rate, you’re researching what kind of waterproofing your shower needs. Good! This post will cover 4 different shower waterproofing systems.

But first…

Is Shower Waterproofing required?

There’s a handbook, especially for tile installers. It’s called the Tile Council of North America Handbook (TCNA). It covers different ways to install tile in different applications.

There are certain sections that cover wet areas like showers. The book gives two different options for moisture membranes. Then it says “Membrane is required”. Now I can’t copy their material because of copyright restrictions but here’s my own drawing based on their information:

tile shower wall construction layers
The layers of a shower wall.

So you can see that, yes there are options for membranes. But a moisture membrane isn’t optional. It’s required.

Moisture barrier or Waterproofing membrane?

What I term a moisture barrier is a membrane that isn’t completely watertight. It can have penetrations and breath-ability.

Examples of moisture barriers would be a sheet of plastic or tar paper that is stapled to studs. It may be loosely overlapped and not sealed completely.

A lot of times these are used behind cement backer board and mortar “mud” walls. It’s a minimal waterproofing system and would be used in areas like vertical shower walls and areas that don’t require more heavy duty shower waterproofing systems.

A waterproofing membrane, however, is a more watertight option. If you have horizontal surfaces, more extreme conditions, or simply want a heavier duty system then you’ll want a complete waterproofing membrane for your bathtub or shower.

For more information on waterproofing the critical areas in a shower see my post:

No Waterproofing: Will this cause shower leaks?

Vapor Barrier vs Moisture Barrier

As far as I know, there is no official distinction between these two membranes in the world of tile. In fact, the term moisture barrier isn’t used in the TCNA handbook. They use the term vapor retarder instead.

But I want to make a distinction between these two terms because a residential shower doesn’t necessarily need a vapor barrier (retarder). But it does need a moisture membrane.

water vapor condensation
A vapor barrier will stop water vapor from passing through

When do you need a vapor retarder?

In the world of tile, you need a vapor retarder when you have extreme amounts of water vapor that need to be managed. If you have a steam shower with a steam generator then a vapor retarder is required.

But most residential showers don’t generate enough water vapor to be problematic. But they do generate enough water to need moisture management.

It can be confusing because even though they serve different purposes these membranes are often the same materials.

Perm Ratings

While this post really isn’t about vapor barriers and perm ratings I do want to touch on the basics.

Perm Ratings:

6 mil plastic sheeting: 0.3 perms

15-pound tar paper:  5 perms

Laticrete Hydroban liquid waterproofing:  1.247 perms (2 coats, each 15-22 mils thick)

Schluter Kerdi Waterproofing fabric:  0.75 perms

Schluter Kerdi-board 1/2″:  0.48 perms

Nobleseal TS sheet membrane: 0.15 perms

If you are building a steam shower then you should know there are very specific ways to build these types of shower enclosures to manage both the water and water vapor that these will be exposed to.

Vapor barriers have perm ratings. To qualify as a vapor barrier the perm rating has to be below 1.0 perms for residential use and below 0.5 perms for commercial use.

This chart has some different shower construction materials and the listed perm ratings.

So that’s the background. Now let’s get to the 4 types of shower waterproofing methods. Starting with

What are the 4 waterproofing systems for tile showers?

vapor barrier shower
Moisture barrier is behind cement board

1. Traditional Shower construction

What is a traditional shower? For years showers were built out of “mud” and a sort of metal chicken wire. The shower floor would have a copper or lead pan, a rubber liner, or a “hot mop” tar waterproofing underneath the tile. Tar paper was stapled to the walls underneath the mud.

While this method is still practiced today over the years those mud walls have more commonly been replaced with cement board and fiber cement backer board. Hardibacker is an example of fiber cement board.

So this is what I’m referring to when I think of traditional showers. These have a moisture barrier behind the walls. Typically the moisture barrier is 4 mil plastic or tar paper. The wall backing would either be mud walls, cement board, or fiber cement board.

Here’s a drawing of how these are built. I’m using cement board in this example.

traditional shower walls drawing
Membrane is behind the backer board

This is an adequate way to build most showers. However, if you have any horizontal surfaces or other critical areas this method won’t work.

No Waterproofing: Will this cause shower leaks?

You’ll need to use what’s called a bonded waterproof membrane. These come in both sheet membrane and liquid form.

Bonded Waterproof membranes

hydroban shower waterproofing system
Hydroban liquid waterproofing is installed over cement board

2. Liquid waterproofing membranes

You’ve probably heard of Redgard waterproofing. Also Hydroban and AquaDefense. These are the most popular liquid waterproofers although there are much more.

The concept of liquid waterproofing membranes is wonderful. You build your shower to any configuration that you want and then paint over it with a liquid membrane and *TADA* It’s completely waterproof!

Unfortunately, the reality isn’t quite like that. Although these liquids are excellent for shower waterproofing there are some details that need to be honored.

Mil Thickness

One of the tricks to applying these liquids is that you get the proper thickness of each coat. This is more difficult than it sounds. Each product will have a requirement for the number of coats and how many “mils” (thickness) is necessary.

wet film gauge
A wet film gauge is helpful to get the proper thickness

They make special tools called wet film gauges. These help to measure how many mils thick a liquid waterproofing is. A rule of thumb is that each coat needs to be “driver’s license” thick. Another rule of thumb is that if you can see the lettering on the backer board underneath then it’s not thick enough. These aren’t hard and fast rules but general guidelines.


Putting the liquids on too thin is a problem but you don’t want them too thick either. More isn’t necessarily better.

Cure times

Another drawback of liquid waterproofing membranes is the amount of time things take to dry. You’ll put one coat of waterproofing on a shower wall and have to wait for it to dry. Yes, it needs to dry completely. Generally, this takes a day for the first coat to dry. Then you’ll need to apply a second coat and allow that one to dry. The second coat tends to dry quicker.

Liquid waterproofing products are constantly improving and so are the dry times. In fact, Custom Building Products just came out with Redgard SpeedCoat which is urethane based and supposed to dry really fast.

Mud beds

We just talked about cure times while waiting for the liquid waterproofing products to dry. There’s also cure times involved with shower mud pans.

A mud pan for a shower is a custom shower base that is sloped to the drain using a cement and sand mixture. It’s still a very common practice today although prefabricated foam shower bases are gaining in popularity.

The traditional way of building a mud pan was to install a waterproof liner inside the mud bed. But when using bonded waterproofing membranes (Redgard, Hydroban, Aquadefense) the waterproofing layer would go on top of the mud pan. Then the tile sticks directly to the waterproofing.

redgard kerdi shower drawing
Waterproof membrane is bonded to the front of the backerboard

The reason I’m bringing this up is that before a liquid waterproofer can be applied to the mud bed the mud bed needs to cure for a minimum of 72 hours in “normal” conditions- so sometimes even longer.

So if you want to build, for example, a Redgard shower the cure times start to add up:  1 day to build a mud shower pan; 3 days wait for it to cure; 1 day to Redgard the shower and wait for it to dry completely; 1 day for a second coat and dry time, 1-3 days to flood test the shower pan.

Reinforcing fabric

One of the perks of using liquid waterproofing products is that they don’t need any special banding or reinforcement in the corners or anywhere else*.

However, my recommendation is that you do use fabric reinforcement in the corners of the shower pan and around the drain and any other critical area when using liquid waterproofing products.

I don’t care what they say on the instructions. It’s too critical of an area to take a chance on. I do know of some shower failures that have come from a separation in these critical corners. It’s very likely this separation would be prevented simply by adding reinforcing fabric or mesh in the corners.

This will add a minimal and probably unnoticeable amount of thickness to these areas but it’s worth it, in my opinion.

*Be sure to read the instructions on the products that you are using. The many liquid waterproofing products don’t require fabric reinforcement but there are still some on the market that do.

valueseal waterproofing membrane
ValueSeal waterproof sheet membrane is installed behind the tile

3. Sheet membranes

The third type of shower waterproofing system is the bonded sheet membranes. The most well-known example would be the Kerdi Shower system by Schluter Systems. But there are many other products- Laticrete has a Hydroban sheet membrane shower waterproofing system and there’s the USG Durock Shower system. Additionally, many others companies like Noble Company, Blanke, Prova, and others have waterproof shower sheet membranes.

What’s nice about these sheet membranes is that you don’t have to worry about the mil thickness of the sheet. Another advantage is that you don’t have to wait 72 hours for the mud pan to cure. Additionally, there’s no applying multiple coats and waiting for them to dry.

The overlaps

But they do have some drawbacks. The biggest one is how you waterproof the seams. Typically, waterproofing is achieved by overlapping one waterproof membrane over another.

kerdi shower preformed corners
The banding and pre-formed pieces add thickness to the corners

Most membrane manufacturers require the sheets to overlap one another by two inches. Alternatively, there’s a 4-5 inch banding material that also is made for this purpose along with preformed waterproof pieces for the corners.

Once you get into the corners you can have both a 4-inch banding material and a preformed corner over the top of the membrane. This adds up to three total layers of fabric. Consequently, this causes the corners to be built up and stick out further than the flat middle parts of a shower.

Other challenges include getting the membrane and the seams to be well bonded to one another and keeping wrinkles out of the membrane.


Wedi shower system
Wedi board is a waterproof tile backer board made out of foam

4. Waterproof foam backer board

foam tile backer board drawing
Foam backer board is waterproof so tile sticks directly to it

Lastly, the final method to be covered is foam backer board building panels. The most popular products are Wedi board and Kerdi board. However, there are a good number of competitors coming onto the market. Such products as Durock foam backer board, Hydroban Board, FinPan ProPanel, GoBoard, and Prova board to name a few. Not all of those may be currently on the market but they are coming soon.

The waterproofing concept is essentially the same as with the bonded waterproofing systems mentioned above. They are waterproof on the surface rather than letting moisture absorb through to the back of the board.

What are the advantages of these backer boards? Well, there are many. They are lighter and easier to carry. The board itself is waterproof so you don’t have the labor of installing cement board and then waterproofing on top of it.

The waterproofing is where they really have an advantage. Usually, they have a urethane glue that you stick the boards together with to waterproof the seams. Others, such as Kerdi-Board, require a banding material that they want you to use like you would with Kerdi fabric.

Basically, once you install the board and glue everything together the shower is waterproofed and ready for tile.

goboard shower backer board
Lightweight, waterproof, and user-friendly comes at an increased cost


As you can imagine the costs are much higher than other options. In addition to the foam board panels, there’s usually stainless screws and washers to buy. Don’t forget the urethane glue either.

Some of the newer boards such as GoBoard, Hydroban board, and Durock board can be installed with cement board screws.

Additionally, there’s more flex in these foam board panels and tile doesn’t like flexing. Some are worse than others. In my unscientific opinion, Wedi makes the stiffest foam panels. As you can imagine they aren’t cheapest either.

Tile Backer Board Breakdown

Well, that’s the breakdown on 4 waterproofing methods for tile showers: traditional, liquid, sheets, and foam. My hope is that this will give you enough information to make a choice on how to waterproof your own shower or tub walls.

Alternatively, it could arm you with information needed for selecting a contractor. Do they intend to use waterproofing? Which method do they prefer? Which method would you prefer?

Let me know which shower waterproofing systems you guys choose to install and why in the comments below.



  1. Hi there, I am concerned with my handyman’s methods and wanted to run it by you. He stapled plastic over the insulation on to the wood framing. Then he hung Durock sheets that had hairline cracks all over it (bc they were installed, taken down and then reinstalled again. Glass blocks dropped on our new tub and damaged the surface, so he had to take Durock down in order to rip the new damaged tub out.) So, my first concern was that he put the same Durock up that appeared to have cracks running through it and didn’t tape or mud it to repair the cracks. Not to mention, screw holes being reused. Then he did not use fiber tape and mud for the seams. Instead he ran a bead of silicone inside the seams. He proceeded to put tile directly on top of this masterpiece. I asked him about putting a waterproof membrane over the Durock and he looked at me like he had never heard of such a thing and didn’t know what Redgard was. He replied saying silicone was enough. All of the information I’ve read and videos I’ve watched state that Durock is not waterproof and that you should put a membrane of choice over it before tiling. I am especially concerned because he did not even tape and mud the seams as directed. I don’t understand how sheets of plastic stapled to the framing is going to keep water from penetrating behind it. Even if moisture was stopped and didn’t find a staple hole or opening in the overlapping seams, wouldn’t it run down the plastic and eventually drop into the wall cavity. The plastic doesn’t go overtop of the tub lip, so where else would it go? Am I overly concerned or am I more educated than my handyman? He’s supposed to do our master bath too, but I’m super worried and don’t want him to move forward with it any more. Also, he’s an acquaintance of my husband so it’s awkward to speak up. HELP!

    • It’s not unusual for people to think that cement board is waterproof but it does, and will, wick water. If you call the Durock people then they’ll tell you that a waterproofing membrane is a good idea and they will recommend their own brand of Durock waterproofing membrane.

      If a sheet of plastic is installed behind the backer board then Durock can still absorb water. However, the water will be protected from getting into the wall cavity. You are correct that it could penetrate through a staple hole, or something, and that’s one of the drawbacks of this type of membrane. But it would take a tremendous amount of water concentrated at this point to be able to do lasting damage. Something that just isn’t going to happen with a properly built shower.

      If plastic is used the plastic should overlap the tub flange so that water would drain into the tub as opposed to the wall. It’s not a bad idea to seal the underside of the plastic to the tub flange either.

      Hairline cracks in the face of cement board are not something to be concerned about. If the cracks penetrate the mesh underneath the cement coating then that’s a problem. When someone cuts a sheet of Durock by scoring and snapping this is what they are doing: cutting through the mesh on one side of the backer board. But a simple hairline crack is usually from flexing and it cracks the cement coating and isn’t something to be concerned about.

      So besides the plastic and waterproofing issues, the other concerns with the way that the board is installed is just the things that you are worried about: Not using mesh tape and reusing the same holes to attach it. Hopefully proper screws are being used but the only way that they work is by grabbing the board. They will lose all their gripping strength if they are installed in the same holes again.

      Additionally, using mesh tape is right in the instructions for Durock, which it sounds like this contractor isn’t familiar with.

      In conclusion, you’re right to be concerned and it’s probably advisable to halt the project until the issues can be addressed. Yes, this may put a strain on the relationship but that’s always a risk when hiring friends.

      • Thank you so much for the quick and informative response. I truly appreciate it!

        • Your story sounds just like mine. We hired a contractor just to install a 4 x 8 tile shower in a home we are trying to move into. He claimed to be the very best and tile showers and did everything wrong from the start, The second contractor ripped it all apart and have got it to the point where he thought it was time to tile but after Reading this post and also showing photos of our job to an actual tile expert it all has to be ripped out again. This information has been very helpful but has left Me in tears once again with no shower no new contractor and no way of moving in to our home

  2. Hi, Jim. Excellent blog — thank you for keeping it up for us DIYers. I’d value your input on my thoughts below.

    I’m beginning a bathroom remodel and have demo’ed down to the floor joists, stud walls and rafters. I’ve contemplated my walls system/waterproofing and done tons of reading. My bathroom is rather small at 5.5′ x 8′.
    We’re putting in a tiled walk-in shower with no curb. This is for ease with the kids and my wife wants to be able to squeegee water from the rest of the bathroom floor into the shower when the kids are messy or she is cleaning the floor. The shower will have a 60″ linear drain at the end (far 5.5′ wall of the bathroom). And one thing you should know: I am very particular about the details, from engineering the structure correctly to the appearance of grout lines and how they interact with the planes of the room.

    1. Although the non-shower portion of the bathroom floor will not really see long-term standing water, should I waterproof it nonetheless? I was considering the 1/8″ Ditra membrane for this.

    2. I hate the crumbliness of cement board and can’t stomach the cost of the waterproof foam boards, so I’m using 1/2″ fiber cement board for the shower floor, walls and ceiling. To achieve the sloped shower floor, I’ll be creatively framing/cleating between my floor joists and recessing my 3/4″ plywood subfloor so that it ends flush with the top of the floor joists at the drain side of the shower; I’ll apply the fiber cement board over that. To achieve the slope I require, can I use 1/4″ board for the shower floor or should I stick with 1/2″ for the added strength? I will be confident in my subfloor strength but don’t know if any real strength/load spreading is gained from a thicker backer board.

    3. After I have my plywood/cement board substrate in place, is it just a matter of applying the Kerdi membrane to that? I planned to go up the backer board walls about 6″ or so, but should I be applying my membrane over the entire wall/ceiling? Articles on this seem to be vague, focusing only on the horizontal surfaces like floors and niches. For my niches, I plan to use the liquid membrane for ease and to avoid the multiple layers of Kerdi membrane.

    4. For the linear drain, I’ll be using a non-Schuter drain so do I need to simply run my shower floor membrane directly into the drain body? I don’t know how else to configure that so that I maintain my waterproof barrier.

    Very much appreciate your feedback.


    • So I’m assuming that you have some sort of enclosure, or barrier between the shower area and the rest of the bathroom. Even a shower curtain will do.

      1. If so, you need to waterproof the transition area where the shower turns into the bathroom floor. So Ditra is ok outside the shower but make sure that you overlap the Kerdi membrane onto the Ditra membrane so that you are waterproof for a couple of feet outside the shower. You’ll also want to use Kerdi band to flash up a couple of inches up the walls outside the shower in this same area. At least 2 feet is what I would say.

      2. If you want to do it this way then it should be ok. 1/4 inch board is fine but make sure that you apply thinset underneath it in addition to fasteners. You’ll need to make sure that you have enough room for the drain to sit at the end. The 1/4 inch fiber cement board should be flush, or slightly higher, that the drain.

      3. Once this is set then Kerdi can be installed over it and up the walls. Schluter wants Kerdi to go all the way up to the shower head at a minimum. I would rather see you use Kerdi for the niches also as I’m not a fan of mixing the two types of waterproofing. Fiber Cement board isn’t waterproof so that’s why waterproofing should go up the walls a ways. Schluter has a Kerdi Handbook on their website that has excellent instructions and it’s worth a look.

      4. It depends on the drain. You should get a drain that works with a bonded waterproof membrane like Kerdi. You don’t want a drain where the waterproofing membrane clamps down below the drain. Most linear drains will have a membrane attached, like the Kerdi drain, or they have a flange that you can bond a membrane to.

      But there are two different kinds of linear drains and you need to make sure you get one that is compatible with surface bonded waterproofing membranes.

      Good technical questions. You’re thinking everything through before you start!

      • Good advice. Thank you again, Jim.

        My last sticking point is selection of the linear drain. I’m realizing that with the design of my shower, everything will really be dimensioned around the drain. I’ll be making an order today. I was hoping to find an affordable flanged drain, but it seems the flange doubles the price of these things. Looks like I can’t escape a $400+ drain!

        I’ll keep you posted on my progress. Don’t be surprised to see a few more questions come down the pike.

        All the best,

        • Jim —

          An interesting update. I just got off the phone with USG asking what adhesive they recommend to adhere their membrane to a linear drain flange. Aside from refusing to recommend anything since I wasn’t using their drain (and I totally understand his hesitation), he was adamant in insisting that I could not use a fiber cement board over the subfloor as my base. He said the industry — not just USG — was unified in this position and that I must either use a foam base product or pour a mud base.

          Any idea on this?

          • The textbook way of building a shower pan is with mud or foam trays. The way that you want to do it isn’t textbook but as long as it’s structurally sound and slopes to the drain it will be fine. The tech people can’t make recommendations outside of the book which is understandable.

            For an adhesive, I would use Kerdi fix, Wedi glue, or whatever you have that is along those lines. Maybe the drain manufacturer has a recommendation?

          • Good to hear that — thank you.

            The drain manufacturer has their own adhesive, but it is not nearly as tried and true as Kerdi Fix, so I’m going with Kerdi Fix. I’ll keep you posted.

            Thanks again.

  3. This is by far the best tiling blog on the web!

    I have the shower down to studs and am going with Rockwool R30 insolation, 6mil plastic sheeting, metal flashing around the 1 inch tub lib, and then 1/2 inch wall hardie backer with appropriate fasteners. Then of course the tile and mortar and sealer.

    My question is that since I am the homeowner, is it advised to use mold inhibiting primer on the studs just in case? Or just leave the studs bare.

    • The primer I don’t think would hurt anything but it’s not necessary. It would be similar if one were to prime the rafters underneath the roof. That sort of moisture shouldn’t be in the wall cavity.

      I would say to put your efforts into building your shower as well as you can. ☺

      I appreciate your comments. Thanks

  4. Hi Jim, thanks so much for the informative blog even for a complete beginner like me who have 0 knowledge on this stuff. What drove me to this blog is to figure out the best way to water proof my bathroom. In the process of getting the estimate to demolish and rebuild the bathroom I came to know the different approaches from different contractors. Your blog mostly covered water proofing the shower wall, not much on the shower pan and I don’t see any diagram on water proofing the mud bed. My question is what are the different methods to build and water proof the shower pan and which way is the best. Thanks so much for your feedback.

    • This is good feedback and I appreciate your bringing it to my attention.

      As you’ve mentioned, there’s different methods for building shower pans and each method has its own quirks and variables.

      In general, I think bonded membranes, like the Kerdi system, and foam pans, like Wedi, are the safest way to build a shower.

      If you are going to hire it out then a competent contractor can build a traditional “water in, water out” mud pan and have it work just fine.

      You make a good point about shower pan information and I’ll work on this for the future.

  5. Do you have any opinions or experience on vapor barriers and insulation in the drywall ceilings and walls in the bathroom? I’m planning on cement boards and RedGard behind tile but the ceiling (including over tub) and the bare walls are going to be GP DensArmor Plus paper-free gypsum board. All the walls with drywall on them are interior but there’s attic and under-heated upstairs space above the ceiling. I’m looking at vapor barrier primers. Does mineral wool insulation with fiberglass-backed gypsum then vapor-barrier primer and mildew-resistant paint sound like a solid plan?

    I see a lot of videos where people put cement board on the ceiling above a shower with liquid membrane on the walls but not on the ceiling. I got the impression the ceiling wouldn’t be tiled. What’s the whole story there? Is there plastic above the cement ceiling and a skim coat of joint compound on the outside in the end (as a guess, I’m not trying to hold you accountable for other people’s work)?

    Sorry for the long question. Thanks!

    • If someone has installed cement board and Redgard on a ceiling I can’t imagine the ceiling not being tiled. There’s no way to paint it, at that point, and the only good way to finish it would be with tile.

      But you never know, and I’m not saying that someone can’t come up with a different way of finishing it but it would definitely be outside the box of it on anything but tile.

      I’m afraid I don’t have good input on the first part of your question but I’m just not that knowledgeable on insulation and vapor primers.

      • Sorry, poor wording again. The situation I was trying to describe is cement board on walls and ceiling but the redgard only goes on the walls. The ceiling is cement board without redgard. This was a Sal DiBlasi youtube video but I’ve seen it elsewhere as well. Do people put cement board on the ceiling and finish it smooth with a skim coat or something to avoid putting gypsum above the shower?

        • I doubt it. There are other products for ceilings if they want to paint up there. Denshield would be one and even moisture resistant drywall would be another.

          Waterproofing is only required to go as high as the shower head so waterproofing on walls and not the ceiling is fulfilling the requirements.

          I’m not saying that cement board can’t be finished, because it can, but it’s my understanding that most drywall finishers would rather see other products for that purpose.

          Sal’s got some good videos though. There’s a lot of bad info on YouTube but Sal’s one of the good guys.

  6. Okay, our house was built in 1992 and I decided to do a DIY remodel of a guest bath shower that had 4″x4″ white tile and is just dated. I ripped out the tile on the walls and noticed it was on green board so I ripped out the green board down to the studs. Then I attacked the shower curb. It was made of the the 2×4’s but with just drywall over it and gaps everywhere. I do not see any liner going over the curb.

    Luckily, or surprisingly, I did not find mold anywhere. Probably because it’s only been used a handful of times.

    I’m a planner and perfectionist and want to do this DIY project correctly. I have time on my hands and don’t have to have this done quickly so I was going to go with the less expensive route of cement backer board and waterproofing membrane than the more expensive foam board options.

    My main dilemma is this…

    I have not ripped out the white ceramic tiles on the shower floor yet but I’m assuming since, I don’t see any liner going over the curb that there is not a liner in the mud floor. Which of the following options can I or should I do? Or do you have another suggestion?

    Option 1: Chip away at the white ceramic tiles and thinset to get to the mud floor. Put up my cement board on the walls meeting the shower floor and redo my curb correctly. Then do 2 coats of the waterproofer (RedGard, etc) everywhere… shower walls, floor, curb.

    Option 2: Remove curbing wood and hammer drill out the white ceramic tile and mud floor down to the cement sub floor. Then rebuild the mud floor with the pre slope, liner and then final mud. Walls would still be cement board with waterproofer.

    Option 3: Remove curbing wood and hammer drill out the white ceramic tile and mud floor down to the cement sub floor. Then rebuild the mud floor with the slope but no liner and just waterproof the floors. Walls would still be cement board with waterproofer.

    Any other thoughts/options?

    Thank you!

    • You’ll want to remove all tile, backer board (in this case- drywall), and tile mud pan. That way, you’ll be down to wood in all directions.

      Now I do understand the appeal of installing a mud bed/liner system, especially if you have time and would prefer to save money. But there’s a lot of steps that have to be done just right to get them to work properly. But if you do choose this route then keep in mind that it should have a preslope under the liner and the curb should be made out of “mud” with no penetrations on top of, or on the inside, of the shower. In other words, cement board should not be used for the curb.

      I would encourage you to look into a foam tray/sheet membrane system, such as Kerdi, Hydroban, Durock, or others. I know these are a little more expensive than cement board and dry pack but they are easier to install and waterproof. With the Hydroban system, I believe Laticrete will warranty the use of their liquid waterproofing with the sheet membrane used on the shower floor so there’s a little bit of flexibility that way.

      Finally, another option would be to use a liquid, such as Redgard, and use that on top of the shower floor, curb, and walls. It does need to be tied into the drain properly but it would allow you to install cement board on the curb and use a dry pack for the shower floor. Make sure that it’s the proper thickness and I highly recommend flood testing any shower that you build, but especially this system. Maybe Custom Building Products has a video for this application?

      But these are good questions to ask and I’m glad that you are researching your options before jumping in.

      • Yes CBP does have a video of how to use red gard in the shower and how to tie it into the drain. I watched it earlier in the week and it was well done. If I do a mud shower pan… I was going to use the Goof Proof pre pitch, and quick pitch system with their curb system and weep protector. The curb would be 2×4 with either liner then their curb system over liner and then mudded. Or if I go red gard route…. 2×4 with felt then the goof proof curb over felt, mudded and then red Gard. Definitely no cement board on curb. Goof Proof shower pan kit had good how to videos too.

        Thank you for taking the time to offer advice.

  7. Here’s a random question: how do you mark guide lines and such over applied liquid membrane? Any problems with chalk lines or pencil marks? Thanks!

    • It depends on the brand and this is where the light green of Laticrete Hydroban works so well.

      But if you are using Redgard or the dark green AquaDefense then you’re going to have a dark shower until it gets tiled. A black sharpie is usually what I use for those brands.

      Believe it or not, this is one of the reasons I will spend more for liquid Hydroban.

  8. I am working on redoing the walls around our kids’ bathroom tub. We pulled the tile and backer board down to the studs. There is a plastic lining already stapled to the studs. The plastic lining is loose and goes down behind the tub and is only on the long wall of the shower (not the faucet or opposite ends). I like the idea of putting up cement board and putting the liquid waterproofing membrane over that before we either re-tile or put up a shower insert. I have two questions:
    1. If I intend to use cement board and waterproofing membrane, should I pull down the plastic sheeting that is attached to the studs first? I read somewhere that we should do one or the other, not both.
    2. Is it wise to do the cement board and waterproofing if we are going to install a shower insert rather than tile?

    • This is a question that comes up from time-to-time and I’ll try to consult some people smarter than me and get their input on this. The plastic sheeting that you see is likely on the exterior wall and is part of the moisture management of your home.

      I know that doubling up on shower waterproofing barriers isn’t recommended but I am not comfortable recommending removing part of your homes insulation system (the vapor part of it) without having a complete understanding of what you are doing and the consequences of it.

      So I would patch the plastic and leave it intact. Then build a waterproof shower as if it weren’t there.

      For the second question, I would think that cement board backing is fine but I don’t know how much sense it makes to redgard over that. While I can’t imagine that it would hurt anything, a plastic shower insert should account for the water management and it’s probably wise to follow the manufacturer’s instructions for it.

  9. Hi, can I install cement board or Hardie Backer to plaster walls? If so, do I need a vapor barrier and should I use some sort of adhesive on the back of cement board befor screwing to studs, Lastly, should I waterproof as well?


    • I don’t know what manufacturers would recommend in this situation and I believe at least one of them doesn’t want their board installed over existing wallboard.

      But the question is: can you? Which I would think is more of a “would it work” question. So it would probably work except you’ll have to locate the studs so that you can screw extra long cement board screws into. Thinsetting the back is probably a good idea. But, in my experience, plaster walls are usually uneven and this can cause problems.

      Rather than adhering cement board to plaster, why not put Kerdi waterproofing over the plaster walls? It’s adds waterproofing and saves a step unless you need to shim the walls out for some reason. An added bonus is that it may even be a warrantied situation.

      It’s worth looking into.

  10. Hi,
    Well, Im nearing the end of tiling my first shower. I’ve used the Schluter Kerdi system and followed the directions to a T, including the water test etc. However, nearing the end of tiling the walls I pulled off the 1″x2″ boards near the bottom that I started tiling on. Then I proceeded to install that very bottom row of tile. Now it’s been two days and I remembered I didn’t seal the brad nail holes that I used to nail the boards up with!!! These holes were hardly visible. They were about 5 inches above the floor.

    I think I know the answer, but do i need to remove those tiles and thin set to seal those holes? Whats the best way? Smash tiles with hammer and chisel thin set off? Uhgg.

    Jeff (not looking forward 🙁 to it ) M.

  11. Hi Tile Guy
    My house is on a concrete slab and the shower was constructed with a mortar bed, smooth river rock was used for the shower floor and cement board with a vapor barrier was used on the walls. I recently noticed some wet drywall at the base of the shower on the outside corners of the enclosure. I removed all the wet drywall inside the bathroom and cut “viewing” holes in the drywall on the back side of the tile walls in the adjacent room and checked for moisture with a moisture meter. There was no water or moisture on the backside of the walls. I also did a water test and found that I do indeed have a leak and can see water coming out on top of the slab. I think its safe to assume there is some type of leak in the liner.

    Is it possible to remove the floor tile and mortar bed to replace/ repair the liner, install a new mortar bed, and new floor tile without removing the wall tile. The wall are large 12 X 24″ tiles in a staggered pattern and am confident that they will be damaged if removed. I don’t have any spare or replacement wall tiles and hoping to avoid installing an entirely new shower.

    Thanks for your advice-

    • In order to properly replace a mortar bed shower pan you will need to go up the wall about 12 inches at least. If you don’t have replacement tiles then you might consider going with a complimenting tile at the bottom 2-3 feet so that it won’t look like a patch but rather like it was part of the design.

  12. Hi Tile Guy,

    I am tiling a large shower with a 10 foot ceiling. Cement board with Kerdi membrane will be used for the shower walls all the way up above the shower head. We are using a Kerdi shower pan with a dry pack mortar extension, of course covered and finished with Kerdi membrane as well. It will be water tested before tiling.

    We are considering using pebble tile for the shower floor. In researching this, a video that I watched said that 1/4′ backer board should be placed over the foam Shower Presloped Floor to prevent the “high heel effect” of the pebbles into the foam shower floor. I had never heard of that. Do you have any advise that you can give, BEFORE I ruin our shower project.

    Thank you in advance,
    Raye A

    • What’s being talked about is called point load where there’s too much weight concentrated in one small spot. This can be a concern with foam pans and small tile.

      I don’t know anything about covering the pan with 1/4 inch backer. I think you’ll have to call Schluter’s tech line and see what they say.

      If it’s a linear drain and one flat slope then I can see how that might work but I’m not as optimistic if it’s a center drain.

      If Schluter says “no” then your options would be to reselect the tile, do a “mud” shower floor with Kerdi membrane on top, or chance using pebbles and hope it’s ok.

      Just because point load can be an issue doesn’t mean that it will. It would be up to you to factor your situation with the risk and decide if you want to take the chance, or not.

  13. Hi Jim, I have an upstairs bathtub / shower I plan on tiling. The walls are made of plasterboard and plaster. The area was tiled previously, but I made some changes to the shower fixture and noticed the wall behind the tile had years of water damage. I removed all the old tile (which looks like it was glued on, a glue resin remains in the pattern in which it was applied). And I removed the areas of the wall which were damaged by water. I had planned on leaving my plaster walls that are in good condition and just replacing the cut out sections with hardibacker. I was then going to Redgard the whole space, over the resin, over the hardibacker and also I will be installing a premade niche if this is not enough ha! I didn’t want to cut out all the walls since they are in good shape, but I wasn’t sure if covering them in Redgard is enough. I’ll be using small, 6×3″ subway tile. Thank you in advance!

    • Also, the previous tile went from the tub to about 6 feet up the wall. I would like to continue my tile to the ceiling, so I will be tiling over resin and smooth plaster. Could I thinset over the resin to make it workable? This is not a project I was planning on doing and if I didn’t have to rip out the entire wall, that would be ideal.

      • I’m not sure what the resin is. Is it glue residue? If so, I doubt that it’s porous enough for thinset to stick to it. You might be able to install a product like Multi Bonding Primer and tile over that but you’ll want to make sure that your situation works as I’m not sure how that product works in a wet area.


        • It’s glue resin, yes. That’s how the previous tiles were installed. The plaster surrounding the tub is 3/4” thick. If I tore it out I would need to match the thickness for the wall transition. Would you recommend putting a 1/2” hardibacker with a 1/4” hardibacker over it or is there a less expensive material I can use? Could I put up sheets of pressboard and cover those in 1/4” hardibacker and Redgard or does it all need to be Hardibacker?

    • I think it’s best to cut out the area that is considered to be the shower and rebuild with the Hardibacker board and Redgard as you had mentioned.

      Plaster walls tend not to be flat and tying into the Hardibacker is sure to cause additional bumps in the wall. Also, I don’t think Custom Building Products wants their Redgard product installed over plaster.

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