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-   -   2015 TCNA Handbook adjustments (https://www.johnbridge.com/vbulletin/showthread.php?t=116576)

Tiger Mountain Tile Inc 05-31-2015 11:24 AM

2015 TCNA Handbook adjustments
 
Got my new 2015 book the other day and I went in to see what's different for this year. There's two things I wanted to get some other points of view on:

Large & Heavy Tile Mortar:


This was hashed out already in this thread and, of course, there's multiple opinions on the subject.

It's my understanding that the new definition is to help the predominately commercial contractors from architects specifying a "medium bed method" and getting around proper prep practices.

I understand that this is an issue and I support the new definition and term. But here's what I want to pick at a little bit:

"where substrate variation exceeds allowances [1/8" in 10ft], LHT mortar (formerly medium bed mortar) cannot be used to remedy such, because the application would exceed the limitations of the mortar."

If LHT mortar can be applied from 3/32" to 1/2" (according to TCNA LHT definitions) the statement above isn't necessarily true.

example: A small bathroom floor, say 7ft long, can have a 1/4" variation. Not unusual at all. Let's say that you install the tile with a LHT mortar and don't flatten it out ahead of time. You'd be within the limits of the mortar but going against TCNA standards.

Edit: I didn't really get at what I meant to get at: With a small floor it's often easier and quicker to forego the flattening process and just install it. This assumes that you are within the limits of the mortar.

I'm wondering if it makes sense to put some sort of exemption in for small floors? Above standard only applies to 100 sq. ft. and above maybe?

What do you guys think of this?

Curbless shower specs


It never occurred to me that there wasn't a curbless shower spec in the book but I'm glad to see one now.

The curbless shower dwg's both show that a reinforced mud bed isn't required under 60 sq. ft. But a reinforced mud bed is required in every other shower spec.

Question: What's so different with the curbless spec that it's different than the others? :scratch:

Tiger Mountain Tile Inc 05-31-2015 11:42 AM

2 Attachment(s)
One more thing that I forgot: Look at the top right photo. A $2 Home Depot trowel with the notches going the wrong way? :stick:

:D

Attachment 176498

Attachment 176499

eurob 05-31-2015 02:52 PM

I am still waiting to receive the new 2015 handbook -- ordered last week -- , Jim .


Quote:

Originally Posted by Jim
"where substrate variation exceeds allowances [1/8" in 10ft], LHT mortar (formerly medium bed mortar) cannot be used to remedy such, because the application would exceed the limitations of the mortar."

If LHT mortar can be applied from 3/32" to 1/2" (according to TCNA LHT definitions) the statement above isn't necessarily true.


That's a very good point there you are making , Jim . I think the LFT is allowing the use up to 3/4 inch and the limitations are not specifying the non use of it for '' minor '' corrections during the installation process .


Quote:

Originally Posted by Jim
I'm wondering if it makes sense to put some sort of exemption in for small floors? Above standard only applies to 100 sq. ft. and above maybe?

What do you guys think of this?

Choosing to not properly prepare the surface of 100 sf. or above , even when non LHT mortars are used , is still present and I don't think it will change any time soon , despite the written recommendations , specific annotations , or basic principles of mechanical engineering .

Caring too much about a tiled installation is not a quality anymore but a sin . Should I hope for better ?

e3 05-31-2015 08:15 PM

You don't need the reinforcing in showers 65 ft.² or less unless specified by architect for project manager ..

Tiger Mountain Tile Inc 05-31-2015 11:52 PM

Thanks for the clarification, Eric.

Btw, I appreciate the people on the committees that are trying to make our trade and industry better. That probably didn't come through in my post above. :)

Dave Gobis 06-01-2015 06:06 AM

If you don't exceed the allowed thickness on the thinset using it it on a flatten and install as you go basis don't worry about it. The change was to further define and elminate using thinset as a floor flattening material followed by another layer of thinset. It is designed for bonding, not flattening.

John Bridge 06-01-2015 06:46 AM

I'm going to join Jim, though. Quit putting statements in the handbook that are not well thought out. Instead of clarifying they are confusing. Just say, for example, that medium bed mortar should not be used as a floor flattener.

e3 06-01-2015 09:31 AM

it does say..."is not intended for truing or leveling substrates or the work of others"
"where substrate variations exceeds allowances, LHT mortar cannot be used to remedy such""

Brad Denny 06-01-2015 12:24 PM

I think much of what we see in the Handbook are changes to help the architect and design community properly specify methods. If you are doing smaller installations designed by yourself, I don't see this as an issue. Use your best judgment to use a mortar within its capabilities.

However, if an architect specifies a "medium" bed rather than a "thick or thin" bed for a huge hotel lobby with a horrible concrete floor, with the expectation you're going to flatten it with thinset rather than get paid for proper floor prep...now we got problems. The nomenclature from the manufacturers put us in a pickle seveal years ago (or maybe the TCNA coined it?)...the new language could be a good defense for tile contractors going toe to toe with someone about the cost of an industry approved method with a little more clarity.

e3 06-01-2015 12:33 PM

Bingo!

Brad Denny 06-01-2015 12:34 PM

Seems like the B421C-15 is also addressing a more commercial scenario. We see this too often...you walk into a job and they want a curbless shower, but the drain is only 1" below floor level and has a 1' birdbath around it. New pour...could've easily blocked out and recessed, but seems like that's gone by the wayside for some reason.

At least now there's a glaring huge picture to catch a specifier's eye. I've already referenced it in writing, good detail IMO.

Dave Gobis 06-01-2015 02:09 PM

Brad your thought process on the thinset change is correct. I made the original submission for those very reasons. What we have now is how it looks after going through several committees. I don't see the handbook referenced in very many residential projects, however I see it on nearly every commercial one. The old term was becoming a huge and costly problem. It was not coined in either instance by TCNA but rather MMSA.

cx 06-01-2015 04:30 PM

Kinda makes ya wish ol' Brad would come to the technical committee meetings, non?

tileaz 06-01-2015 05:24 PM

I would love to see Brad at the technical committee meetings. It needs to be said that the whole "medium bed" issue was getting out of control. I have run into 20-25 specs in the last year that dropped the slab one inch and that the tile needs to be set in a medium bed method. This specification destroys the chances of a responsible tile contractor because he/she will bid by the rules. I am on my soap box, but the whole "anti-fracture" nomenclature is as dangerous as owners are expecting that no cracks occur even in the grout joint. Remember the term crack isolation, and the ANSI standard is crack isolation, there is no industry recognized standard for anti-fracture membrane. Eric will agree that crack isolation is the theory of moving the crack in the substrate to the weakest part of the tile installation which is usually the grout joint. The allied manufacturers have to do a better job of educating the owner, architect and builder. As Dave will attest, it has taken 7 long years to try to fix the medium bed issue, because the product was sold in such a haphazard way.

dhagin 06-01-2015 05:50 PM

Can one attend those tech committee meetings remotely, or does a body have to be there? :)


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