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cement board as shower pan

48741 Views 121 Replies 22 Participants Last post by  Mike Finley
I am new to this forum and new to the tile trade 39 years ago. I know that this is not the place for advertising. I have figured out a way to use cement board as the shower pan. I will be attending the "Total Solutions" conference in San Antonio in Sept. given by the NCTA and after that I will be using this sight to PURCHASE advertising space and with that display the website link so anyone can check it out.

My question is :

I wanted to know if anyone has seen a post that discusses the use of CBU INSIDE the shower AS the pan.
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The technique does use a waterproofing in it. No it's not Fin panel. The reason I have come up with it
is that I see the "old school" mud sets not being taught properly. The dinosaurs like myself are dying off and the younger tradesmen are not learning from qualified teachers.
I checked the search box and can't seam to find any threads that talk about it. I just was fishing to see if there was any interest in using stock off the rack cement board ( PermaBase - Durock) to build a 100%
waterproof shower pan.
Please don't take it wrong that I meant the younger tradesmen are not as "skilled. The technique I have
come up with would allow a homeowner with a skill level of say 4 out of 10 do this. No hot mop! The base
is waterproof. Old school mud set used pre-pitch mortar and vinyl liner because they knew that the tile
and grout were NOT waterproof so they expected them to allow water through to the liner and then (in a perfect world) to the weep holes. Since my method is 100% waterproof BEFORE tile it works the same way with much less skill required to get a preferred pitch towards the drain. In all due respect Mel, allow
the possibility to re-think "the way it's done"
ChrWright , You say that using CBU as a pre-slope is not a new idea. How is it used like this?
Kevjob , We are still in the launch stage and have already been contacted by the TCNA for the process to get it into the handbook. That takes time. Your building Dept.will see specs when it makes the handbook
ChrWright , I hear you. That's what I'm talking about.Atleast you are thinking outside the box.
Many people steer me to the Schluter website. I can build a 48x34 shower pan complete for about $200.00
I don't have to order the materials and can pick them up at any "big box" store. Schluter makes great products, but they cost alot more. Next , someone will tell me "you get what you pay for." If you can do the same job for less money that makes sense to me
Ray D , Do you have anything to add?
Good Night Everyone, Thank-you for your comments. Unless a man is willing to listen to other views he will not be able to learn from others wisdom. I do appreciate the wisdom that this forum will bring. I will check back often.
I see your website links to Schluter. I said before it's a good product. There is room for both of us out there
I need to stay fuzzy on this until after the Total Solutions conference on Sept. 17-18. I'm sorry. I have a non-disclosure agreement with a couple of entities and I will be able to give the details after that. I am a professional of 39 years in the trade a can appreciate your frustration when someone says he has a better mousetrap and then won't show it. No we don't cut the board into pie shapes, PermaBase and Durock are the two boards that will work. A vinyl liner gets clamped into the clamping ring of a standard two part drain ( oatey , Sioux Chief). Liquid water proofing like Mapei Aqua defense or LATICRETE 9235, hydro ban are used at different intervals to actually "waterproof" the cement board, fiber mesh is used to "tape" all corners and wall to floor, verticle wall corners and threshold. AND a SECRET as to how the board is pitched with FULL support under. Again I'm sorry for the need to be so vague at this time. I will try the JohnBridge site and continue to post on this site after I am legally able to. Please be patient.
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Again I can take all of these responses as valid concerns. Not all people ( Harry Homeowner ) would try
to do this type of work anyway. The trade pro's will be the guys that I will need to convince and I KNOW
that this will be a large task. As for 9235 being a mesh based anti/fracture, it's a liquid waterproofer.
Brushes or rolls on. In our market, outside of Chicago, fabric is available at the Home Depots and Menards
I'm impressed with the job that Christopher posted. That is GREAT work! We agree that 9235 is difficult to work with. I use Aqua Defense and Hydro ban more. I still use a fabric with it to "tape" ALL the corners. For a test, I did my process and then flood tested
a shower pan and left the water in it , unprotected with tile/grout, for SIX WEEKS. Not a drop. If my process can keep a pan waterproof for 6 weeks , it can hold up to a 15 min. shower. To answer the $200 question. NO that's not M-n-L. Materials only
using $90 cost for liquid waterproofing. In my market I get an additional $400 labor for about 2 hours work. Maybe some guys can't work that cheap but I'm ok with it. The tile install is above and beyond this cost. I am promoting the construction of a shower pan,
tile ready, using cement board and my technique. AGAIN I AM VERY GRATEFUL FOR ANY NEGATIVE COMMENTS. Unless I get the other side, I may of overlooked it and you guys are my piers and experts on this subject. I will be able to "Unleash this Revelation"
by the middle of Sept. But I am encouraged that there has been this much interest and debate on it. It shows me that maybe mud set bases may be going out and the newer products that are different may be the new standard .
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Welcome back gentlemen, Hydro ban literature says fabric is required only "at all joint, coves and corners" I'm reading that from the literature I have in front of me.So, I'm not suggesting anyone should use a product for something it was not intended for.A mini unit has about 50 sq.ft coverage. Enough to do a standard (48x34) pan with multiple coats. The pros like yourselves buy in quantity. The $200 number I've used would be an average cost if you purchase only enough for one pan.The costs go down per pan since your buying in a larger quantity you will have enough material to do multiple pans after the initial investment. A commercial unit ( 5 gal.- 250 sq.ft. is not 5 times the price) I have talked with LATICRETE about the possibility of including fabric with the mini units and rightfully so, they will wait to see the response and acceptance of my technique first.

The quote "and it's acceptable by the TCNA" comes from Mike's question. I didn't say it was endorsed yet at this point. I said early in the thread that I have been contacted by the TCNA as to the process to have it considered for the handbook. That takes at least 2 years. They are accepting requests now for the 2011 book.

Let me ask a question first. Is it true that the traditional method of mortar base pre-slope EXPECTS that the water WILL penetrate the tile and grout AND the mortar.So, water transferring and being trapped into the mortar
is just part of what is to be expected. Weep holes are designed to allow the water an escape but I'm sure you know that they can't be 100% effective in doing so. I'm trying to waterproof the pan above the substrate ( mortar in the traditional case) My liquid waterproofing is in theory doing the same thing as the liner except that the water isn't trapped below.Any water that penetrates the tile and grout(this will be a very, very small amount) will evaporate up and out. Not down and out only.

Am I thinking so wrong here? EVERY mortar base I have taken out had standing water trapped in the liner.No one has been able to actually prove to me that weep hole/pre-slope combination will work all the time. You will say that the pan was improperly built. Then EVERY pan I have seen HAS been improperly built and I go back to my statement that some of the problem is that we are not training the younger guys the proper technique. So, this technique I have come up with replaces mud set pans,does it well,and does it for less that the higher priced alternatives on the market. I wait for comments and again welcome critique.
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The liner is not under the complete base, but does clamp into the drain and leaves the weep holes free
and clear.I do this not because I expect the waterproofer to fail but if ANY water should penetrate I feel it will be around the drain/grout and this will allow the water to fall straight down and escape.

Again, The product "Custom's WONDERBOARD" is not one that I recommend. It is too rigid. Yes there is a step where the cement board is somewhat "Flexed" . Are you familiar with Perma Base? Everyone knows USG Durock. The process allows the bases to be formed in any shape and size. I did a 30"x30" and a shower that had a floor sq.footage of 42 ft. ( 6x7 inside)
I am sorry but I will be unavailalbe for the rest of today ( Sunday ) to answer
questions. I will check back tomorrow and address any more concerns. Thank-you again for your interest.

"Let me ask a question first.Is it true that the traditional method of mortar base pre-slope EXPECTS that the water WILL penetrate the tile and grout AND the mortar.So, water transfering and being trapped into the mortar
is just part of what is to be expected. Weep holes are designed to allow the water an escape but I'm sure you know that they can't be 100% effective in doing so.
Sorry for the confusing use of "vapor". I'm sure you know that I mean "Water"
We have seamed to of got off point. I still contend that mortar bases are not
"waterproof". They do allow WATER to be transferred through into the mortar base and we should agree that it would be best if it didn't. Kerdi waterproofs the base from above. Check this thread. I have not once said anything bad about Schluter. It seams a lot of guys on this site bleed orange.I'm not trying to convert you.At a point in time Schluter was new and no one was familiar with their process.That is where I am right now. I present the option to bulid the slope to the drain with a special use of cement board.Water proof it with the best products available today, and then it may be tiled.

Please re-read my post #44 sent yesterday 10:27 am. Particularly the last paraghraph. Does anyone disagree with my statement?
I will try to upload a picture of what I mean.
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