bad mortar?

[LarryT]

I installed a schluter shower kit yesterday, polystyrene pan with hardie backer walls and kerdi membrane.

I'm prepared to get beat up for this, but I typically buy Custom thin set from Home Depot. They were out of stock of Custom Blend unmodified, I went to Lowes and bought what appeared to be the Laticrete equivalent (Laticrete Floor Adhesive, unmodified, meets ANSI 118.1).

I waited 20 hours or so, occupied house with heat, and water tested the pan. The kerdi started to bubble up and within a minute was nearly floating off of the floor. It pulled away without resistance. The mortar is soft to touch, particularly where it got wet.

I called Schluter, they said that they've never heard of a failure like this. We reviewed trowel notch size, etc. and they concluded that it sounds like thin set failure.

Laticrete's tech support was less helpful. The guy was in denial of any possible thin set problem from the beginning. "why did you buy the cheap stuff? What did you expect?" Apparently Laticrete offers two grades of unmodified thin set, this was the only one that I saw in Lowes. He offered absolutely no technical advice, potential solutions, concern for the problem with the Laticrete product in the field. He was quick to explain that their only obligation is the purchase price of the mortar and that I should look for their better grade of unmodified. I was seeing red at this point, don't recall the product number of the "good stuff" as I had already sworn to never purchase any Laticrete products in my lifetime.

I called Schluter back, they recommended that I pull off all of the kerdi, hose it off and reuse it over a different thin set. They suggested a laticrete product or mapei. I asked about Custom Blend and he said he preferred the others without offering any reason.

I have used Custom before with good results. now I'm really confused. Laticrete admitted to making a product that is cheap and apparently unfit for its intended purpose to be marketed against the good stuff, does Custom also have a premium line that I'm unaware of? I called Custom tech support, got much more advice about the situation than laticrete offered, but it ended with a discussion about Custom disagreeing with Schluter about using modified or unmodified under the kerdi. Custom only makes one grade of unmodified, again it has worked for me in the past.

I have scraped down the hardie backer, the thin set was very sandy in texture. Tomorrow I would like to reinstall the kerdi, but I'm not sure with what and I a little worried about bond over the residual Laticrete "cheap stuff".

Any ideas?

Larry

[mbyrne]

Re: bad mortar?

LarryT,
I was hoping to see your profile filled out, but there was nothing there. Members here like to ignore new members whose profile is blank because profiles sometimes hint at a poster's level of experience. I am going to guess that you are new to tile installation or are not too concerned about the quality of mortar. I have no intention of beating you up about your choice of thinset mortar, but I'm pretty sure that if one of your kids (if you have any) brought home a D report card, you would be furious.

I am curious about the water test, and your statement: "The mortar is soft to touch, particularly where it got wet". Did you try to peel back one of the seams to see if the thinset mortar was hard? Was the Kerdi stuck down tight? How did you fill the pan area? Did you direct water to any of the seams? How did the thinset mortar get wet? If you can provide some answers, we might be able to give you an opinion.

I am familiar with the shower kits, and the only way I can think of that the Kerdi would "bubble up" is if water was forced into the seams. I have done water tests on this product within hours of installation and did not have a problem - I have never experienced Kerdi Floating off the surface.

[NateMoss]

Re: bad mortar?

Larry, never had an issue like this. I did recently buy 4 bags of laticrete 317 and 2 of them were horse ****. They had a ton of sharp aggregate in them which made embedding the thinset impossible. I was told that I must have gotten a bad batch or the end of a batch. I was not happy. I have used custom from home depot and it has done ok. A lot of guys like to use versabond - a slightly modified mortar. Can you get your hands on some ditra set?

[LarryT]

Re: bad mortar?

Sorry about the profile, Michael. I've been lurking here for years and never bothered to fill it out. I am a residential contractor and I have done my own tile work for years.
I actually am concerned about the quality of the mortar, I'm posting in search for advice. In the past, Custom Blend has worked well as far as I can tell. I have not had kerdi come loose from it and it was waterproof, I assumed that an unmodified mortar is pretty generic product. If this product earns a "D", I would like to learn why and which product to use instead. There are some discussions around suggesting a modified thinset to bond the kerdi. I don't know enough to stray from the manufacturer's instructions so I have continued to use the unmodified Custom mortar without problems. The Laticrete product looked similar, met the ANSI spec, was similar in cost to Custom, I assumed it was the same.
The Kerdi appeared well bonded to the walls and laps, there were no bubbles in the surface. I installed a test plug and poured water from buckets directed into the drain, it filled from the center without being directed at any seams. After the second or third bucket, I noticed the 'floor' sheet lifting at the edge by the curb. It was still bonded to the piece of kerdi band that was in the corner, both were coming up. By the time I went for pliers to remove the test plug, an area about 15" diameter was raised around the center of the shower. The kerdi was still bonded to the fabric of the drain assembly, but it was floating around it. I grabbed the kerdi at the drain opening and I was able to lift the sheet off without much resistance. The mortar under this piece was wet from the failed test, otherwise it all appeared dry and cured.
The walls appear dry but without good bond, the kerdi pulled off without much resistance. Scraping the residue from the walls, it is very sandy, not hard at all.
I followed thin set instructions, allowed it to slake and remixed, etc. I try to be pretty thorough.
Can you recommend a specific unmodified mortar if you dislike the Custom Blend, and can you offer any ideas to guarantee that the new installation will bond over the residue that is left from the Laticrete?

Thanks

[Shawn Prentice]

Re: bad mortar?

Larry, you should start a thread over at JB concerning this:

http://www.johnbridge.com/vbulletin/

There are a handful of Laticrete reps over there including one of the owners, Henry Rothberg. I'm sure he will be very receptive to this and your experience with their tech department. They seem to care about their products and the customers interactions with their distributors/reps/techs, from what I've seen. A lot of tile setters over there use the Laticrete products.

[jsbeaton]

Re: bad mortar?

Hi Larry,
I recently had a conversation with Schluter about what Laticrete unmodified mortar they recommend. Their answer was Mega Bond. I wonder if the bubbles could be air pockets?

[scuttlebuttrp]

Re: bad mortar?

Schluter reccomends a "Premium unmodified".
For Laticrete; that would be 272.
Tec's Fullset Plus.
Ditraset.
All of these are priced way north of $10 per bag.

I heard Custom still makes Masterblend but it's only sold in Canada.

I talked to a guy from N. Carolina and he swears by unsanded thinset if you can get it. Custom Surebond at Home Depot is sometimes available, but I'm not familiar with the quality.

[NateMoss]

Re: bad mortar?

Larry, just wondering if the kerdi bonded to the flange and the other kerdi around the perimeter..... where how did the water get in? Also, if you stuck it to a mud bed, the mud be could have easily sucked the moisture out of the thinset rapidly not allowing it to bond to the kerdi.

[mbyrne]

Re: bad mortar?

LarryT,
Thanks for the detail account of the install. Sounds like you did everything right. To be on the safe side, I would have waited 48-hours before water testing. You should always test the bond before adding water. A good way to do this without compromising the pan material is to build a test seam. I do this, at the time the pan is going in, over a scrap of drywall or backer board: I bond the Kerdi to the board, then create a seam over that with another piece of Kerdi. On special jobs, I would make two such samples. Before water testing, try to pull one of the samples apart. If you can, wait another day.

As for the best thinset mortar, I would use Hydroments Kerdi mix (or is it Ditra mix?) Very fine sand, lowest profile seams, and ultra-compatible with the Schluter products.

As for tech reps who immediately say "You did not mix it properly" before asking real-world questions, I immediately take that as a sign that the company policy is to stonewall to limit liability. I have been an enthusiastic supporter of many different products over the years. I used to have a favorite manufacturer who supplied all the thinset powder, latex mortar and latex thinset additives. Used the products for years until I had a problem with a rep who must have thought I was born yesterday. After dissing me without asking a single question regarding where, when and how, I dropped them as a supplier, have never used them since, and have never shown the company name on sacks or buckets in any article I have written.

With another manufacturer, I was doing a job with my photographer on his house. We set up our cameras and began shooting while I installed self-leveling compound. We had a complete photo-documentation of the job from start to finish. Used two sacks of SLC. Next day, one batch had setup, the other did not and would not after 48-hours. It seemed like it took weeks to remove the hardened SLC, the galvanized expanded metal mesh, and the resistance wiring mat.

I was goint to call the mfg to see what the problem was, but, instead, I asked Mike to call the supplier. Their first response was "You probably mixed it wrong". The second response (before asking any questions was "We are not responsible". You gotta love that about Home Depot. Next, Mike called the manufacturer. Their two responses, again, without any questions, were: "You probably mixed it wrong" and "We are not responsible" and then practically slammed the phone down on Mike.

Next, I called HD and reported the material failure. Same responses. Then the goofus said "You probably have no experience installing tile or working with this material". I told him to walk over to the book rack and look at one of the tile books for sale. He exclaimed "that is the best book on the rack". I got his name, went to the store, and asked him if I could autograph his copy. He turned white, gave me a lame excuse for his phone manners, I walked out of the store. then I called the mfg and explained the situation and introduced myself. The response? "If we had known it was you, we would have jumped right on it" What BS! That mfg actually replaced a few people in the tech department, and they seemed to have changed their ways.

It is totally unacceptable when mfgs are more interested in damage control than the needs of their customers.

[David Meiland]

Re: bad mortar?

I don't know if it helps at all, but I always pay attention to the way products behave after I dispose of what's left. Thinset and grout scraped out of the bucket get put on a shingle of CBU and left to dry, or I bond a scrap tile to CBU and let that dry. I check it out before I take out the trash. I do the same with epoxies that I use in the shop for gluing wood and other materials... usually use a paper beverage cup for mixing those, and I leave the cup and the mixing stick propped up in the trash barrel so I can check it out later, after I expect the material should have cured. Last year I glued up a small project using 5-minute epoxy from a dual syringe, and it did not cure, it stayed gooey for days after mixing. I had to clean and reglue the project, and I went to the source of the glue, took all of the packages off their rack and up to the counter, and told them to check every one of them before they sold them. A few weeks later they were stocking another brand.

You cannot discount the possibility that your thinset had inadequate cement in it, or some other defect. The building industry is increasingly filled with deficient products ranging from sacks of ready-mix concrete to $6000 refrigerators. Google concrete and cement failures and read about a litany of ruined projects and contractors.

[Anita@LATICRETE]

Re: bad mortar?

Larry,

Thank you for your inquiry and we are sorry that you had a problem.

In order to better understand what has happened and what can be done to resolve the problem, please let me ask a couple of questions;

1. Did you install the Schluter Kerdi with LATICRETE Floor Adhesive on the Schluter Shower System and onto the HardieBacker Board?
2. Is the loss of bond only on the polystyrene shower system, on the HardieBacker Board only, or both?

I look forward to your reply and to helping you with the problems which you are experiencing.

[LarryT]

Re: bad mortar?

Thanks for all of the replies. The thin set seemed like it was dissolving when in contact with water. I think this was a good installation, again no air pockets, back of the kerdi sheets all showed 100% transfer after I pulled them off. As the thin set got wet, it just turned to mush and admitted water. The loss of bond was from any surface that got wet- kerdi to polystyrene, hardie backer or kerdi to kerdi lap seams. The common thread is the thin set.
I pulled all of the kerdi off of the shower, the 24 hour old thin set rinsed off with a hose, clean enough to reuse (per the schluter rep). Getting this crap off of the walls proved more challenging. It was really sandy and had no bond to the hardie backer that I felt I could depend on. I scraped the walls again and again, each time I could still feel loose sandy grit after scraping. I washed the walls agressively with a scrub brush, scraped while wet, and washed again.
I went to the tile shop for new thin set. They are Laticrete dealers, I swallowed some dignity and bought the 272 mortar, knowing that if this won't bond I will have to speak with that rude jerk in Laticrete's tech dept. This seems like a better product, it is much richer and stickier than the "cheap stuff", but I still feel like I am rewarding their bad behavior.
The kerdi went back up uneventfully, I dampened the hardie backer with a sponge before each piece. I had intended to go there tomorrow afternoon to water test, maybe better to wait until sometime on Sunday as Michael suggested, the additional dry time might be cheap insurance. With any luck I can set tile on Monday.

Thanks again

[LarryT]

Re: bad mortar?

As for tech reps who immediately say "You did not mix it properly" before asking real-world questions, I immediately take that as a sign that the company policy is to stonewall to limit liability.

It is interesting that the tech rep NEVER asked about the mix or application. He immediately threw his own product under the bus, "what did you expect from this stuff? it only has a one year warranty"

I felt like I had reached the legal department rather than tech support.

[David Meiland]

Re: bad mortar?

I know this has been a huge headache, but it sounds like you're on your way to a nice, professional recovery.

[Robert Z]

Re: bad mortar?

I installed a schluter shower kit yesterday, polystyrene pan with hardie backer walls and kerdi membrane.

I'm prepared to get beat up for this, but I typically buy Custom thin set from Home Depot. They were out of stock of Custom Blend unmodified, I went to Lowes and bought what appeared to be the Laticrete equivalent (Laticrete Floor Adhesive, unmodified, meets ANSI 118.1).


Larry

Anita from Laticrete can confirm this, but I think that the "Floor Adhesive" that is sold in Lowes is what used to be called Laticrete 280. If so, I wouldn't use that for a Kerdi installation.