What actually does an uncoupling membrane do?

Users who are viewing this thread

Vegas_sparky

Digital Billy
Messages
486
Reaction score
42
Points
28
Location
LV,NV/ Nowhere,UT
John, I've been spending too much time doing temperature controls for things like jet fired power plants, and 20,000 HP central plants. LOL
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
John, I've been spending too much time doing temperature controls for things like jet fired power plants, and 20,000 HP central plants. LOL

And, I'll bet systems designed today with today's state of the art, while similar, have introduced new technology for bot the construction, control, and monitoring of those plants. Does that make the old ones bad? At some point you need to assess the new and decide if it fits your needs better than the old stuff. But, some people are abjectly resistance to change, and in John's case, anything Schluter, or me! The man carries a grudge a very long way and holds nothing back, whether founded or unfounded. One of the reasons he's been banned from a few sites dealing with similar topics and responses. Check out the materials themselves, any one of us may make a mistake, our minds aren't perfect. Do some independent research, don't listen to just one person, myself included, before you make a decision. John's just got a chip on his shoulder...take it for what it's worth.
 

Vegas_sparky

Digital Billy
Messages
486
Reaction score
42
Points
28
Location
LV,NV/ Nowhere,UT
John, do you think the profile of the mat would change at all with finish materials installed? You know I have no dog in this fight, but I can't believe there's no way for anything to bite into that stuff.
 

Vegas_sparky

Digital Billy
Messages
486
Reaction score
42
Points
28
Location
LV,NV/ Nowhere,UT
My man card's secure. I carry it with me wherever I go. LOL

I test whatever, but that'll be about as irrelevant as can be. After all this talk, I don't even know what you're testing for.
 

Eurob

master tile and stone installer
Messages
824
Reaction score
53
Points
28
Location
Montreal
Website
www.houzz.com
JW said:
You guys check your numbers with mine.

Just send them to me -- your numbers -- . I will post the same saying '' as per my test , the numbers are ....." LOL ;)
 

Eurob

master tile and stone installer
Messages
824
Reaction score
53
Points
28
Location
Montreal
Website
www.houzz.com
John , just reversing the thinking of the application is raising questions . The theory of uncoupling and protecting it from thermal stress is just send to the back door .

On the other hand , the exterior installation face the thermal stress from an opposite -- outside to inside -- perspective than the heated interior floors -- inside to outside -- and uncoupling is still recommended .

And then there are the different and variable temperatures of the materials in the assembly -- concrete slab ( on grade and suspended ) , plywood substrates , mortar beds , thin set , uncoupling membrane , tiles , etc. -- , summed to real life situation -- sun exposed , shade , humidity , cold or hot temperatures , etc . --


Usually time testing is the most relevant but for now is almost impossible to get the failures in written literature -- easily accessed -- , besides the usual '' installer error .''

Have fun with the testing :)
 

Eurob

master tile and stone installer
Messages
824
Reaction score
53
Points
28
Location
Montreal
Website
www.houzz.com
Sparky said:
Coverage of the SLU can't be controlled(floating cables). That's unpredictable. Neither can coverage of thinset if its on top, unless you burn a layer in before you set. Those materials act as heats sinks for the wire, and their characteristics are engineered into the performance. Without those materials hot spots in the cable will develop, which affect there service life.


Will , Now the wire is in direct contact -- more of the unpredictable ? -- with the uncoupling membrane , SO there is no constant -- variable wrapping -- heat sink for the entire length of the heating cable . Much worse than the embedding of the wires with SLU and cover it with the adhered -- thin setting it -- uncoupling membrane .

But then again , it is negligible , right?
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
The steps have no back bevel on them. This is easy to check.

What do you think holds the cable in place? It encircles EACH tower - it snaps into place because there's a back bevel. The most any single tower could have a cable in that slot is over 90-degrees when making a corner since you cannot just run it around the post...you cannot put the heating element closer than every third slot. That slot along with the shape of the whole mat, lock the thinset and tile in place. That you don't have an open mind and can see that for yourself and have to bash others says something about your character.

The thinset is mechanically locked in place on Ditra Heat, which holds the tile in place.

As to overheating...you do not want any significant air space around the heating elements or they can overheat...they must be (at least for the majority) covered in thinset. Try turning on your electric water heater without filling it up first...a very dramatic example of the need to be able to conduct the heat away...works fine when covered, burns up very quickly without. You need some mass there and the plastic mat doesn't have any by design.

Ditra, and many other decoupling membranes have those raised ridges with air space underneath them and, consider, a heating element could easily be running straight along the top of one, at least somewhere in the installation. If you put the heating mat or elements on top of the mat, you'd have the heating elements crossing or following those air spaces...a great situation for a hot spot over each one. Ditra Heat is designed with minimal direct contact of the wire and the majority of it being encased in thinset and, those spots where it might touch the mat are relatively far apart compared to the structure of other uncoupling membranes, minimizing any heat buildup at that point. It's a matter of reliability. You MIGHT be able to make it work otherwise, but it wouldn't have the reliability of an engineered solution where they take into account the heat rise and the material properties. You can do that when you produce both the heating cable and the mat so you know how it works...that is a big unknown when you try to mix and match things from various suppliers. Another reason why these things are called systems, and not just components. And, Schluter is very conservative - if you install things like they say, you have as close to 100% probability it will work as designed as humanly possible.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
I'm glad he changed his screen profile picture. Any Red shoe image makes me a little sick these days.
FWIW, I never selected that picture...one day, it appeared. Since it didn't really matter to me, I never changed it. Terry tends to add one if the user doesn't pick one.
 

Vegas_sparky

Digital Billy
Messages
486
Reaction score
42
Points
28
Location
LV,NV/ Nowhere,UT
I'm sure this product went through extensive testing, but IF that mat was on a ceiling, would you stand under an 18"x18" piece of tile/stone set to it? Just out of speculation.

I have to say, any mechanical bond to that profile looks like it'd be pretty weak. The lip has nothing to leverage against. The ridges on rebar aren't very big either, but they don't pull. Set a mat/tile on a temp board, hang it upside down, attach a suction cup and weights until it drops.

Double or nothing a 12"x12" with any properly mixed/cured thinset will pass a garage test with a suction cup and 20lbs hanging straight down off it.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
It IS specific as a FLOOR warming system. Using it elsewhere would not conform to the intended use. A good uncoupling membrane makes the tile/thinset layer much closer to a floating floor than any bonded system, minimizing any shear stresses, which is one reason why a good unmodified way exceeds the requirements to hold anything in place (an unmodified's minimum bond strength is 150psi, and a good one can double that putting it at over 5x the bond strength of the membrane), and that's what gives it the benefits...gravity does much of keeping things where you want, with the shape of the mat taking care of the rest, isolating it from the subfloor. The industry spec for this type of thing is a minimum of 50psi - it doesn't matter what the size of the tile is. I haven't seen test results for this mat, but feel very confident that it exceeds the industry standards.
 

Jadnashua

Retired Defense Industry Engineer xxx
Messages
32,770
Reaction score
1,190
Points
113
Location
New England
It's made out of the same plastic as the other Ditra uncoupling mats, if that helps. Once installed, and you've filled it up with the thinset and set the tiles, the actual flexibility of the mat is what provides the stress-relief in the lateral plane. The air space in the towers is what allows it to move horizontally without cracking the thinset or breaking a tile(not vertically)- IOW, it MUST be flexible to obtain the uncoupling. Keep in mind, you still have the rigid tile bonded to the thinset that keep the towers in place, only deflected as a whole assembly (tile/thinset). The areas where the thinset goes to the base of the mat are what provide the vertical support, and their spacing is the reason why there is a minimum tile size requirement - the tile needs to be supported by a minimum number of thinset towers to provide adequate compressive strength, only limited by the compressive strength of the mortar used. If you don't wear kneepads when working on your knees, you might want to use a kneeling pad, but you won't hurt the mat in the process - it will be more comfortable for you. That's pretty much true for any uncoupling mat.

That is one reason why, as opposed to say a crack isolation membrane which needs to span a ways over a crack to have enough flexibility to actually isolate it, an uncoupling membrane does that from its inherent structure over the entire mat, regardless of its size - things can move any direction laterally, independent of the subfloor or slab and the width (contrary to what John thinks) has no impact on its decoupling capabilities.

Any test trying to exceed the industry standards with any mat are misleading and mostly useless...all membranes of this type must meet a minimum of 50psi to pull it off the substrate (the fleece attachment layer will fail first), and that will be the weakest link in the system. The only way to determine how well it works for uncoupling would be to install multiple strain gauges in the sandwich, and measure how much stress can be applied before either a tile or a grout joint fails or breaks. No backyard test is going to do that, and with crude measurement tools, is mostly a joke and pointless. These things are designed for use on a floor, and you're not going to have something yanking the tile up (gravity doesn't work that way) or pull it sideways. Yes, the tile and the substrate move separately, but that's the whole reason for an uncoupling membrane, to isolate them. For any practical installation, it far exceeds anything needed. It does NOT reduce the need for expansion joints IN the tile - it only works between the substrate and the tile - the tile's expansion can exceed the strength of thinset regardless of whether it is attached via bonding directly or whether it is placed on an uncoupling membrane. The beauty of the uncoupling membrane is that thinset does NOT stick to it (at least on Ditra - why one would want fibers as part of the tile bond is beyond me, and probably mostly to avoid patent issues - they state that they tear in the process, anyways, so why have them!).

The whole concept of you must use a modified thinset for attaching porcelain or glass IS true, IF you direct bond them in many cases. When using an uncoupling mat (and the installations from centuries ago used their version of an uncoupling mat - a packed sand bed - no cement, just sand and their glass and porcelain installs work just fine), you have probably at least a 300% stronger bond to the tile than any lateral stress that can be applied to it. IOW, it isn't going to come off unless you try to destroy it!
 
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