What actually does an uncoupling membrane do?

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Jadnashua

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In testing the Dural uncoupling mat received a heavy Commercial rating in the TCNA Robison Floor test. What did the Ditra heat mat get Jim?

FWIW, the rating categories of the Robinson floor test are: residential, light, moderate, heavy, and extra heavy. The description of the test result describes what they deem each level to be suitable for.

Ditra heat, like any uncoupling membrane, will give different results based on the tile, the substrate, and some random factors based on the wood involved, and the fact that humans and nature aren't perfect, but look at test report TCNA-415-13, with OSB, 19.2"OC, and a 12x12" porcelain tile, it received an EXTRA HEAVY rating...the highest they give, (and better than the heavy you're so proud of) and also, Schluter pays for multiple tests, and only lists a rating that passes that level for EACH test sequence...some get one good rating, and use that, ignoring the others...nothing's exactly the same - Schluter wants it to work, when they say it will, regardless as long as you install it the way the say (something, you have a problem doing). They ran a bunch of tests using natural stone over Ditra with a single layer of plywood...the majority of the time, it passed the tests with a reasonable margin, but not 100%. As a result, they do not warrant natural stone over a single layer of ply...the result of being conservative and wanting to know the user can ALWAYS get it to work, backed up by testing, when installed as they say. They do not like 'ifs'...if it doesn't work, they either fix it during design, or don't sell it. That doesn't mean they don't make changes along the way based on feedback or technical advances or production methods, but the products have to continue to work as advertised WHEN INSTALLED ACCORDING TO THEIR INSTRUCTIONS (again, which John Whipple has a big problem with, thinking his way is better - sort of the NIH mindset some companies have (not invented here - if I didn't do it, it can't possibly be as good).

Maybe a little research, rather than the knee-jerk, typical of you, reaction may be worth considering.

For those of you who may have been following this since the beginning, John Whipple doesn't like me, dislikes anything I say, and tries to pick apart any bit of it. He now, also dislikes Schluter because they told he they were not pleased with his unscientific comparisons, incorrect installations, and various comments about their products...talk about vindictive. Schluter has been in business for decades, products sold around the world, has innovated many of the advances in materials and techniques for tile installations. That I admire them, is partly because I'm an engineer, retired, having worked in designing, testing, and teaching troops how to use various missile systems for over 30-years helps me to recognize and appreciate that innovation and professionalism Schluter has for their products and how they treat their customers. In my job, failure to do what we said could mean thousands of lives lost and billions of dollars in property damage - IOW, you have to get it right the first time. My experience is that Schluter has the same attitude, but like anything, you have to use it as it was designed. I have used products from other companies, and some are as good, some are lousy, and some have no overlap, so there is no choice. I have no agenda here, I do not get any commissions, or rebates, or financial incentives to post anywhere. John has an interest in making himself look good (and an obvious ego) and promote his business, and anyone that challenges something he says is an enemy...I think you get what I mean.

Uncoupling mats work. You may not always need one. To me, if your choice was a cbu or an uncoupling mat, the uncoupling mat would always win, even if it cost more. For a pro, because of the speed and ease of installation, more than a few pros I know will only install cbu if the customer insists - the difference in cost of materials is easily covered in the time savings (labor is often a significant portion of the job)...the customer is always right, even when they're wrong. When the probability of failure isn't a big issue, yes, either will work, and one may be overkill (but John LIKES overkill, if you follow any of his methods). There are times when an uncoupling mat will be the only sane solution, but in many cases, you can get by without one.
 
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MACEOD

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I hope someone is still out there. I have a FL slab home with several structural cracks discover after pulling up the carpet. The cracks range from between one-eighth and one-quarter inch, I am filling the cracks with a high-quality epoxy resin prior to having a professional level the floor. I want to isolate the slab from the tile to preclude the transition/formation of new cracks should the slab develop a new crack. The new tiles are large format so any movement will be problimatic. From all the reading I have struggled through, I require a crack isolation membrane.......yes/no? If so what are the top choice for my situation?
 

MACEOD

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OMG i am now posting a reply to contradict myself...............so maybe it is an uncoupling mat I need and possibly a beanie with a propeller to whisk me away. You guy talk pro to pro, I am on the other hand an wanna-be. Take pity, give me some good advice!
 

Jadnashua

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First, if those cracks have any vertical height difference, you should NOT tile the surface at all! If they are spreading cracks without any vertical height differences, you can tile it but, an uncoupling membrane is not going to isolate the tile from the cracks...for that, you need a crack isolation membrane. Uncoupling are different than crack isolation. In some situations, you might want both.

Industry standards call for 'honorning' the crack with a soft joint in tile above the crack. That can be an engineered joint or a grout joint filled with a caulk. Depending on the area's use, there are different 'caulk-like' materials that have different hardness, and thus service life. Some of them are available in matching grout colors, but not all.
 
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