Installing cement board behind my shower

[KatrinaK]

Hi Everyone,

I am remodeling my bathroom and am at the stage where I need to put the cement board up behind my shower. There is some vapor barrier there, but on the interior walls it only goes about half way down the wall. Does anyone have any thoughts on if I need to add more vapor barrier? There used to be drywall behind the shower, I'm not sure if having cement board now changes things?

Also, I am not sure how far down the cement board should go. The drywall that was there previously looked like it was just above the tub line, not touching it. This is one of those shower/tub combos.

Any thoughts on this would be greatly appreciated, I am very new to the do-it-yourself world!

Katrina

[jadnashua]

You do want a vapor barrier and bring it down lapped over the tub's tiling flange. You only need the cbu up to the height of the showerhead, but you can go further. To keep the cbu from bowing out, you can shim the studs, notch the studs (and recess the tub's flange so it is flush with the studs), or stop it slightly above the flange and make sure the tile is more than half supported on the cbu. The tile should not be touching the tub, but a slight gap that is caulked.

[KatrinaK]

Thank you Jim, this helps a lot !

[johnfrwhipple]

Katrina look into waterproofing products as well.

For another $70.00 you could make the entire tub surround waterproof.

Products from Mapei and Laticrete would be Aqua Defense, HPG and Hydro Ban.



The green product is Hydro Ban in this picture. You can see I used a waterproofing chalking to fill the tiny gap between the backer board and tub. This was done after I waterproofed the tub.

There are sheet membranes from many companies like Kerdi, Noble Seal TS, Noble Wall Seal, Jaeger, Wedi and on and on. The ones that allow modified thin-sets I think are best so avoid the Kerdi membrane if you can.

The Vapour barrier behind your interior walls is to provent moisture from wicking through the grout and the cement board. Why not stop it first before it even gets there?

Make sure the cement board does not flex when installed. Many home owners use under powered drills that do not set the board tight to the wall stud.

Tape the seams of the cement board and do not pin the cement board tight to the tub.



This is a free standing tub that sits into a corner. On the right side is an exterior wall and the left just a regular wall. On this project the entire home was spray foamed so no vapour barrier was required. The blue product is Mapei HPG a one step waterproofing system. I brought the waterproofing down the cement board and onto the tub deck. Later like the other project I used a little Kerdi Fix.

Good Luck.

JW

[galerie]

Can LATICRETE Hydro Ban be installed on Durock Backberboard?

[mtcummins]

Correct me if i'm wrong, but I believe you should NOT have both a vapor barrier behind CMU and waterproofing over it. Its one of the other, and the waterproofing over CMU is the better option by far.

Personally, I use Kerdi on walls and Ditra on floors with modified thinset (typically versabond), with no problems. I know that John Bridge over at his excellent tile forum (that JW above doesn't seem to like too much) does the same at least with Ditra, and he's been doing it a long time w/o problems. However, it will void the warranty if you're worried about such things, so its your call. The other options he suggested are also good ones, I just happen to like Schluter's products.

Can't tell you about hydroban on CMU, maybe someone else can, or read the specs on it. it should tell you the suitable applications.

With most waterproofing, CMU is overkill, though I like its stability and sometimes will use it. With Kerdi, I generally just apply directly to MR gyp board. Not sure what the other waterproofing methods require, but this is how Kerdi is specified to be installed.

[johnfrwhipple]

Can LATICRETE Hydro Ban be installed on Durock Backberboard?

Off Course.

Hydro Ban is an excellent product and if you go this route you will have many options in thin sets for the tile setting. With newer larger format tile it's nice to get the anti sag mortar (this is modified thin set) and with Hydro Ban you can use it.



Here is a look at more Hydro Ban installed in a walk in shower. Using a liquid waterproofing also aids in simple shower niche construction. Remember that a niche can not go on an exterior wall as it will not have any room for insulation.

It's true I don't care much for the Schluter's line of products. There is not much to like about them. For one it is the thinnest protection in waterproofing products at 8mil and one of the hardest to work with. When setting Kerdi over Durock you need un-modifed thin set and this dries very quickly when the Durock steals the moisture from the thin set. With modified thin sets you have a longer working time and a little more forgiveness. I could be wrong about Kerdi being the thinnest membrane - does anyone know of a thinner product? Noble Seal TS is 30 mil. Think about it. Your credit card or bank card is about 30 mil thick. Kerdi is roughly 1/4 that thickness. Hydro Ban is 20 - 30 mil when installed properly as are most liquid membranes. Each coat thicker than Kerdi.

You can use Noble Seal TS if you like sheet membranes and this like Hydro Ban allows for installation of all thin-sets without voiding the manufacture warranty.

Remember that your local building inspectors will require you to follow all the manufactures printed guidelines. This is my core beef with the Schluter product line.

Versa Bond is a cheap thin set and Kerdi the thinnest protection to my knowledge - for my clients and customers I demand more.

John Bridge is retired, he no longer sets tile for a living - John send me an email a couple years back saying just that. I believe John Bridge sends his refferals to a setter named Paul now. I believe John Bridge's income comes from selling products from his online tile store and selling Kerdi EBooks. I make my living installing showers and waterproofing showers. It has taken me a long time to learn all the different approaches and I don't think the Kerdi product is bad - just limiting and hard to work with. Each user should research these facts personally - Call Schluter and a thin set supplier and ask for the facts.

Often what you are told by tradesmen or by online posters is not what is best for your home but what is best for the tradesman or what is best for the schedule. we use what's best for the client and what offers up my company the best possible product with the least chance of failure.

Why break a manufactures guidelines and your local building department's guidelines? Makes no sense.

Installing drywall in a wet zone is a poor building practice - the worst. I understand that all old loop holes are closing on this method of construction and if you contact the NTCA (of which I'm a member) you will be hard pressed to find anyone endorsing this as an acceptable shower backer board.

Showers should be built to last not build with the cheapest, thinnest products. Shower backer boards should be strong and waterproofed after installing them properly. Waterproofing should be applied topically and all showers should be flood tested - every time. Demand it of your crew.

If you call Laticrete you will get excellent tech support and with the right selection of products build a bathroom with a 25 year warranty.

If you build it with Kerdi and modified thinset you will have no warranty unless you get prior approval - to date I have never seen nor heard of anyone getting an email or letter from Schluter allowing this.


Weighing all the facts it is a pretty easy decision.

JW

[jadnashua]

I welcome opinions, but everyone should consider that the people expressing them, myself included, are individuals, and we're all different. Re John Bridge's forum...John Bridge has probably tiled more years than John Whipple has been alive. The fact he is now retired is somewhat irrelevant...he has more time to look at new products. His site has numerous professionals that make their entire living doing tile projects, and has many more opinions, than this forum. They have Latticrete and Noble reps that can answer questions and, while John preferred Schluter products, he and others have and continue to use others when the situation dictates. So, regardless of whether he is retired or not, there are many others that are there, including a structural engineer, available to help. You, as an individual, have every right and the responsibility to look at your options and make your own decisions as to what is best for your situation. Just like Terry doesn't answer every question, on the John Bridge forum, you wouldn't expect him to answer all of yours...you'll get many opinions with enough pros to often get some relevant choices, backed up by years of experience.

[hj]

Vapor barrier is ONLY effective, or needed, when there is a temperature differential between both sides of a wall. An interior wall does NOT have that differential

[johnfrwhipple]

...John Bridge has probably tiled more years than John Whipple has been alive...

John Bridge only used Kerdi I believe for perhaps 8 years and then retired. I believe I flood tested more showers last month than John Bridge did in his entire career. I believe he commented on one of his Kerdi threads that he did it once or twice and then felt it was no longer necessary. I find it odd that such a well respected tile forum does not promote flood inspections. If you look into this Jim you will I believe find one example of a John Bridge flood test. It's that crazy shower built with a couple of 2"x6"'s for a curb.

I do not think I have built more shower's than Mr. Bridge. I do feel that his acceptance to installation guidelines that differ from the manufactures recommendations is wrong. I also feel that Schluter's position of not correcting it is wrong. I also think that most of the posters on the John Bridge forum are made by people who actually don't even build showers for a living.

I think people should build proper showers. I think people should install mortar and waterproofing products as directed by the manufactures. I think all drains should be installed by plumbers not tile men.

Like you said Jim we are all individuals and we all have our own opinions. I want to see a reduction in land fill waste. So many showers fail because of poor construction. failures do to installer error. This is why we flood test showers in permitted projects and all new construction.

Everyone online should research the facts.

I offer up only my expeirence and share my successes here in Vancouver. I would love to see a few Kerdi flood tests. Perhaps Jim you can post a few of yours?

I would also like to see Shark Bite fittings taken off the shelves and sold only to plumbers. I would like to see all residential water lines pressure tested. I would like to see all drain and vent lines flooded. But there is only so much time to type. So I monitor the waterproofing side of the internet.

Jim your good friend of Mr. Bridge I'm sure. Maybe you can ask him to promote flood test on his forum for me? Maybe you can start a thread and promote them. I have never read any post of yours where you recommend someone to preform them? I do read post after post - year after year your postings on how easy Kerdi is to install.

Help me out Jim. Get the boys on the John Bridge forum to recommend flood tests. Think about how much waste can be saved from these dump sites.

As far as tech support that is easy. If you want tech info from Noble call their 1 800 line ask for Richard or Eric - tell them John from Vancouver says Hi.

If you need help from Laticrete call Anita - she is a sweet heart and will get the right tech.

Mapei ask for Shawn.

No need to type just call. It's free and these people work for the manufactures and can advice you or anyone the proper install techniques.

Here is the contact numbers for my three favourite suppliers;

Mapei 1-800-361-9309 (Canada) or 1-800-992-6273 (U.S. and Puerto Rico)
Laticrete 1 (800) 243 - 4788
Noble Company : 1 (800) 878-5788

For proper Schluter System install instructions call;

USA 1 (800) 472-4588
Canada 1 (800) 667-8746 ask for Courtney

Online facts should always be confirmed by the manfacture. Check with your manufacture's local rep and always follow the printed instructions.


JW

[johnfrwhipple]

Vapor barrier is ONLY effective, or needed, when there is a temperature differential between both sides of a wall. An interior wall does NOT have that differential

Thanks for keeping on us track HJ.

The vapour barrier debate and moisture sandwich concern is a very difficult question to answer.

If you are building a traditional shower for example (one using a three piece clamping drain and pvc liner) it is very common for the plumber to install this drain and liner before the vapour barrier of the home is installed. Now the plumber can get his flood test inspection pasted, have his drain lines and vent lines flood tested and have his water lines pressure tested.

Once this is done and the local plumbing inspector is happy they will sign off on the Plumbing Rough In. Next the Electrical gets checked both the low voltage and regular voltage. The Gas lines need inspecting and approval. When all of these trades have completed their work the structural engineer will come and sign off on the homes framing and then you can call for a framing inspection from your local building inspector. Your building inspector will want to see all the copies of the other inspections.

So no you can insulate and vapour barrier.

A shower on an exterior wall may have a small piece of vapour barrier between the top two plates which the 6 mil poly (vapour barrier) gets tied into. Often it's not there and the insulating crew will bring the poly from the bottom plate up the wall and across the ceiling.

In the shower the poly will lap over the liner and be sealed to it with a little accoustical sealant.

So by the time you are ready to board a shower renovation this process should be done.

If you are skipping Hydro Ban, Kerdi, Aqau D and such it would be wise to add more poly to the remaining shower walls and lap them over the PVC membrane. Then use a cement board, tape your seams (Install as directed by the manufacture) and your good to go.

Hardi Board, Wonder Board or Super Panel all good options here in Vancouver.

If you do plan to waterproof your shower there is no need to waterproof the walls up to max ceiling height. Most times we stop ours at about 6' 6" above grade. If there where any moisture trapped in the walls it can migrate through the wall board and breath out the top 1.5' of wall space.

If your waterproofing with Kerdi - same thing.

[hj]

Another thing. The vapor barrier is installed on the "heated" side of the insulation and its purpose it to prevent that "moisture" from getting into the insulation, where it would condense into "real" water, NOT keep it out of the wallboard or "stud space".

[jadnashua]

In John Bridge's first book, he said he used Versabond, but later on, he came to agree with Schluter, that a good unmodified was more than adequate, and I think his second book shows that. While other good dryset mortars are available, the formulation of DitraSet swayed him, I think along with discussions with the manufacturer. The reason Versabond worked, is that is it only slightly modified, and drying isn't as critical for it as for some others...it's close to a reasonable quality dryset with a little kick, if you will.

Lots of people flood test their showers there. There are numerous pros that comment in the forum, and a lot of DIY'ers, too, just like here. The only time the thickness of the membrane might be an issue from a durability point is during construction where you may have it uncovered and say step on it with some debris (say a nail or screw). The beauty of the sheet membranes like that is that you can do the walls (almost to the pan), then do the pan so you don't have to walk all over it in the interim. Plus, because the stuff is thinner, you get less buildup in the corners and junctions. I have no problems with people preferring other materials. My limited experience and training is with Kerdi, and it's met my needs and desires. I do believe that if you are conscientious about getting good coverage with the thinset and the proper overlap, that a flood test with Kerdi is somewhat overkill, but certainly doesn't hurt. And, if the local code officer wants one, it should be done, regardless. They do highly recommend you get a permit and the subsequent inspections.

Once you've done a few, it's easy to tell visually if you've got a good bond, and bubbles and ripples are easy to spot (and shouldn't be there in the first place if you install it well). Painted or rolled on materials are absolutely required to have a flood test, as it's easy to have a pinhole leak, or insufficient coverage. A traditional liner would be foolish to not do a flood test, as it typically needs to be cut and patched for the curb, then you have a thin clamping drain that you may not have screwed down evenly or tight enough. On the Kerdi shower I built for my mother, the inspector came, looked it over, approved it without a flood test. He understood the material, and inspected the construction quality. I was trying to complete it over a brief Christmas holiday, in between entertaining, while 400-miles away from my own home, so time was important, as was the availability of the inspector to come without losing lots of time because of the holiday and having to wait potentially days in between his visits.

[johnfrwhipple]

Jim you kill me.

So if you use the thinnest membrane out there it's OK to skip a flood test, but if you use any other system then it is necessary. That's funny.

I frequent the John Bridge site weekly and no one recommends flood tests. Who are these posters you refer to?

It is quite the opposite in fact. If anyone suggests the use of a liquid the "Kerdi Boys" are quick to talk about pin holes and that a flood test is necessary. Flood tests are required and need to be preformed before tiling the walls.

Installing Kerdi properly is tough. You must get it just right and any bump or rock in the thin set can cause failure. Any stone in the dry pack can puncture the membrane. Any dropped tool. A screw in a work boot. A clients high heels at night while reviewing the days work. A dropped trowel..... and on and on. In about one out of every 10 shower we build a missed stone or such will puncture my sheet membrane from Nobel. I fix it with ease with a patch. Noble Seal TS is nearly 4 time thicker than Kerdi and I would think at least 3 times as puncture resistant. I feel every square inch after an install and then flood. When doing liquids I inspect by eye (for pin holes) and touch up. And then I flood.

The fact that the flood tests are skipped only serve to speed up a project for a tile setter. People want cheap and easy.



Here is a look at a job we did four months back. Guess what? They skipped the flood test and installed the Kerdi wrong. This was a "Handy Andy" doing waterproofing here in Vancouver. What a waste of material!



This is a Kerdi Test box I made. It held water fine and passed my flood test - but look at the wicking. Any seam not done properly will leak. This is why you need to check your work.

There are other sheet membranes that use modified thin sets for seaming and they work fine. In Europe Kerdi is installed this way.

You must flood out a shower. It's so wrong that you sell and push Kerdi so hard and in fact that you don't do this for a living and recommend poor building practices is horrible. Shame on you Jim.

I get it that John Bridge is your buddy and all your online buddies write and answer questions on that site. I think you help so many people and you do a good job but to mis lead online writers is shameful. Your comments and push to send people his site only confirms my suspicion that you might in fact be an employee of the John Bridge Tile Forum.

If you receive "Tips" in your Christmas Card for your help funnelling internet researchers to the Bridge Forum I hope you can sleep with your conscience.


The durability of the membrane is paramont in construction. All sorts of traffic is going on on construction sites. The very act of setting tile can stress the membrane.

Thanks for the laugh Jim.

Happy Thanksgiving.

JW

[jadnashua]

So if you use the thinnest membrane out there it's OK to skip a flood test, but if you use any other system then it is necessary. That's funny.

I frequent the John Bridge site weekly and no one recommends flood tests. Who are these posters you refer to?

Not what I said...a traditional pan liner, absolutely, a paint on membrane, absolutely, a properly installed sheet membrane, always a good idea, but kind of overkill. The beauty of a membrane, is you can even tile the walls before you even build the pan...so, you leave the bottom row off, install the pan and then seam that joint. You can water test then. Then, tile the floor. Much less chance of damaging the pan liner. If you happen to drop a trowel after your flood test, you'd be in the same situation.

Since most places require a water test, this discussion is kind of mute, and, the guys over there regularly tell people to get a permit and inspection. So, there's a flood test. When you tell your kids to get dressed, do you have to tell them to put their shoes on too? Hopefully not if they're older than say six.

A DIY'er could do a flood test and not tile for weeks...the test is kind of useless unless they are very conscientious about protecting the material. For that, a traditional pan is probably better, since the mortar bed protects it.