Traditional shower pan - can anyone point me to more info?

Users who are viewing this thread

Awake

New Member
Messages
13
Reaction score
1
Points
3
I've been perusing the posts on this forum, but haven't yet fully understood the way a traditional shower pan (with a preslope, PVC liner, and upper layer of mortar over top) goes together and works. Several questions, or perhaps someone can point me to more information:

1) What binds the upper layer of mortar to the lower layer and/or to the floor? It seems to me that the pvc liner creates a complete separation between the layers. Is that correct?

2) How is the wall tied into the pan -- as I understand it thus far, the preslope is made and dried, then the liner is installed in the pan, over the curb, and up the walls the requisite amount. Is the second layer of mortar then applied before the cbu is put on the walls, or the other way around?

3) moisture barrier on walls -- I think I am seeing two different approaches; one is to apply a moisture barrier behind the cbu (consisting of basic plastic sheeting?); the second is to apply a moisture barrier on top of the cbu, either in the form of a liquid membrane such as RedGard, or a sheet membrane such as Kerdi. What are the advantages/disadvantages of these two approaches?

4) final question -- if a liquid membrane such as RedGard is used, can or should there be a second mortar bed over it, or can (or should) thin set and tile be applied directly?

Thanks for any help!
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
Your questions require loads of time to answer.

Why not start at the beginning. Call Noble Company.

Decide on your tile and grout. Then choose the best approach.

Avoid at all cost cheap unmodified thin-sets. That would be my single biggest recommendation for you.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
The TCNA has two slightly different techniques for building a conventional shower - it depends on the type of cbu you use. There are essentially two classes of the stuff: fiber-cement (like Hardibacker), and an all-cement board.

1. The bottom layer is either bonded to the slab, or if a subfloor, you'd use something like tar paper and lath nailed to it. The top, setting bed is not anchored or bonded in place...it is held together by the walls/curb, it's depth, and it's weight.

2. If you use a fiber cement board...it gets harder to anchor the bottom of it in place because you must leave a gap from the bottom of it to the setting bed and can't put nails or screws through the liner until you are at least 3" above the top of the curb. But, if you use an all-cement board, you can run it down to just above your horizontal liner, then when you install the setting bed, assuming you did your blocking correctly, it will be anchored by the setting bed.

3. This is a huge topic with many opinions and some facts. A properly done surface membrane keeps moisture out of the walls entirely. Keep in mind that cbu is not waterproof, but is not damaged by being wet (well, a fiber-cement board might be, but they are still pretty robust). I prefer a sheet membrane rather than a liquid one, but either can work.

4. Generally, (you should read the respective company's shower instructions for details), you set your tile directly on top of the surface membrane. If it is installed properly (and with a liquid, that includes the two layers being properly applied and between the min/max in thickness), it works.

Check out the 'Liberry' (sic) at www.johnbridge.com, where you can find all of this discussed in some detail.
 

Eurob

master tile and stone installer
Messages
824
Reaction score
53
Points
28
Location
Montreal
Website
www.houzz.com
More of the sending to the other site ..... '' act like you know '' ....... my faith is gone now .


Just before I go ....
 

Eurob

master tile and stone installer
Messages
824
Reaction score
53
Points
28
Location
Montreal
Website
www.houzz.com
I've been perusing the posts on this forum, but haven't yet fully understood the way a traditional shower pan (with a preslope, PVC liner, and upper layer of mortar over top) goes together and works. Several questions, or perhaps someone can point me to more information:

1) What binds the upper layer of mortar to the lower layer and/or to the floor? It seems to me that the pvc liner creates a complete separation between the layers. Is that correct?

2) How is the wall tied into the pan -- as I understand it thus far, the preslope is made and dried, then the liner is installed in the pan, over the curb, and up the walls the requisite amount. Is the second layer of mortar then applied before the cbu is put on the walls, or the other way around?

3) moisture barrier on walls -- I think I am seeing two different approaches; one is to apply a moisture barrier behind the cbu (consisting of basic plastic sheeting?); the second is to apply a moisture barrier on top of the cbu, either in the form of a liquid membrane such as RedGard, or a sheet membrane such as Kerdi. What are the advantages/disadvantages of these two approaches?

4) final question -- if a liquid membrane such as RedGard is used, can or should there be a second mortar bed over it, or can (or should) thin set and tile be applied directly?

Thanks for any help!


1) Yes . It is an unbonded method .

2) The second layer is applied before the CBU with a small gap in between . No water -- capillary action -- need to go further up the wall , if the CBU is in contact with the mud -- second layer of mortar -- .

3) MB behind the CBU for a traditional shower pan , liquid or sheet membrane on top of the CBU and the mud (mortar ) layer -- no preslope and PVC linear needed . Soaking wet and slow drying times -- first option -- , minimum accumulation and fast drying time-- second option -- . There are other factors which need to be in to have it right -- coverage of the bonding agent ( mortar adhesive ) , sealer for stone applications , capillary barrier from floor to walls , etc. --

4) No second mortar bed over it . But there are installations out there in which it can work -- hybrids -- , but not for a DIYer to try or risk . Too much can go wrong if misunderstood .

Just a small fraction of what it takes to do it right . Far from the whole picture or a true understanding .

Good luck .
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
....Just a small fraction of what it takes to do it right . Far from the whole picture or a true understanding .

Good luck .

I wonder about the dry out times Roberto. I have some strong thoughts on this and wish I had more time to test out some theories. A properly designed traditional shower with a "Whipple Style" weep system just might be the fasted drying shower system to date.

A topical shower with modified thin-set might absorb less and dry out faster - or not.

A topical shower with cheap ass non-modified thin set might absorb the most and dry out slower than my design.

Problem is no one tests this data - it's all speculation.

The NTCA has no studies or data for Vapour Sandwiches or Weep Hole Preformance. All speculation or stats online are just word of mouth rumours backed up with no NTCA or TCNA facts.

As yet there is not one official study on either. Lots of Bull Shit and speculations talked about by men who don't know their ass from a hole in the ground - but nothing official from any group I would look up to.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,771
Reaction score
1,191
Points
113
Location
New England
The TCNA outlines numerous ways to build a reliable shower. Each has their benefits and detractions. Once you decide on a method, then you have to decide on whose materials you want to use, and again, each of those has benefits and detractions.

For a class of installations, I prefer a surface applied waterproofing. There are numerous companies that make materials that can provide that type of install. Each has their own details. Laticrete, Noble, Schluter, Custom, and others all make one or more types of surface applied membranes, either in sheet goods or liquids, and some make both. The showers I've built, I used Kerdi. I've used RedGard to repair a professionally built shower that failed (the builder broke lots of industry guidelines and workmanship criteria) because my sister didn't want to do a full tearout and rebuild at the time. What we did was sufficient to keep things from failing for a bit. None of the showers I've built (the oldest now about 10-years) shows any signs of leaking or failing in any way.

What is critical, is that you abide by the manufacturer's instructions and have reasonable workmanship. It's not particularly hard, but it is very detail oriented. The tile is just the pretty wear surface...the shower should be built to be reliable before that layer is installed. IOW, no caulk or grout or tile applied really waterproofs the structure - it must be built correctly prior to those finishing steps. A pro may be able to make that outer, wear surface (tile) look nicer than a DIY'er, but that isn't a certainty. The TCNA says that 70-80% of the tiled showers built are not done correctly and that includes new homes, hotels, etc. that were done by 'pros', or at least someone who was paid to perform the work. There are good installers out there, but not all in the business are good. 'Look's are only part of the overall job of building a reliable shower.

As to www.johnbridge.com, lots of 'traffic', a big pool of professional people and talented non-pros to answer tiling questions along with a useful reference library of industry specs, and helpful guidelines. A few people here also post on that site...try both sites and see what you get.
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
Boys - once you activate the "Block Jadnasha Feature" this is all you see....

Screen+Shot+2014-07-05+at+8.03.55+AM.png

The best new feature on Terry Love's new platform !!!
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
Are you joking? Jim does not even work in the business. Nor does he tile for a living. I doubt he has even built a shower since not once has he showed anything he has created.

He builds links.

He sells Kerdi.

He is a salesman - not a tile man.

I'm surprised you would say that....
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
OK - I get it. Sarcasm....

To be fair I've been drinking today! I missed the little smiley face and its meaning.

When in Mexico.....

OMG - did you see the one timer goal from Argentina today? Or are you at work?

Freakin Amazing.

My beloved team is still in it...... HELL YA
 

Eurob

master tile and stone installer
Messages
824
Reaction score
53
Points
28
Location
Montreal
Website
www.houzz.com
I did see it John . It was a very well placed one timer .

Argentina has a great team . Lots of player can score at any time . The Belgium goalie is Messi's Kryptonite . ;)
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
.... The Belgium goalie is Messi's Kryptonite . ;)

Messi was off today.

Me and the kids painted some pottery the other day. I painted an old style taxi cab (piggy bank). Painted it out to be the MESSI MOBILE in Argentina colours accented with Green and Yellow.

Picked it up today after they glazed it and it looks so cool. Stand by for a new AVATAR Photo. My little one is asleep right now. She's got swimmers ear. My fingers are crossed the doctor says she can not fly tomorrow!!!

Another few days in Mexico would be welcome.
 

Eurob

master tile and stone installer
Messages
824
Reaction score
53
Points
28
Location
Montreal
Website
www.houzz.com
Sorry to hear that John . I hope she gets better soon .

On the other hand ...... just take more time off ........ even if the doctor is saying good to go .

Messi was off for the last 8 games against the Begium's goalie .
 

ShowerDude

Showers
Messages
710
Reaction score
66
Points
28
Location
Minnesota
John, based on your last or current project price quote you shared with us, id say a vacation is in order!! And a few extra days afforded! I have just raised my prices !!!!


Be safe in the 3rd world. ....Any cool tile down there?
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
John, based on your last or current project price quote you shared with us, id say a vacation is in order!! And a few extra days afforded! I have just raised my prices !!!!


Be safe in the 3rd world. ....Any cool tile down there?

What where you charging before?

Check out the new AVATAR.... The Messi Mobile. Hand painted no less! Who says I can only built kick ass showers? I got a future in Piggy Bank Design I think.
 

JohnfrWhipple

BATHROOM DESIGN & BUILD
Messages
3,225
Reaction score
102
Points
48
Location
North Vancouver, BC
No cool tile. Lots of 2'x2' porcelain. Some cool blue and white glass pool tile. Nothing exceptional.

I like the gravity trench drains they have in the breeze ways. I'll snap a picture later when my little one wakes up.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks