# I Screwed Up! Wrong Thinset....Now What?



## Robdude (May 12, 2009)

Not sure if this is the right place to ask - I'm installing ceramic tile on my walls around a bathtub.

I ripped it down to the studs, leveled them as best I could, installed a vapor barrier, installed 1/2" Durock Cement Board, and then began installing tile with an 'unmodified'/Dry-Set thinset.











The bag says, "*When mixed with water: for interior/exterior residential floor and wall installations of most ceramic tiles, ceramic mosaics, quarry tiles, pavers and dimensionally stable natural-stone tiles *"...That's all I did. Just added water.

I've since heard that I should have used modified thinset. The difference in price of the Thinset is trivial; but my problem is that I've done two of the three walls in my shower already!  

Totally my fault for not double checking - but what should I do now? If I leave it 'as-is' can I expect the tiles to fail horribly and just start falling off the wall? That sounds dangerous and I certainly don't want that. Do I need to basically start over? Can I salvage the tiles I put up already?

Thanks in advance for any help.


----------



## Bob Mariani (Dec 1, 2008)

if the tiles are not falling off the wall leave them alone. The modified thinset is stickier. That is about it.


----------



## 26yrsinflooring (Jul 1, 2008)

Well.... sticker it is but there is a little more going on than that.

The thinset you have is a top quality brand, Mapei.
If you are wondering how it is pronounced it is (mop-a)

You should be fine since you used a good thinset.

Latex modified thinsets were the best thing to happen to the tile industry. Before latex was introduce there was no way to bond the polymers together and offer greater strength and flexibility.

Your setting is simplistic, around you tub, it should be fine. Changing thinset with not impact the job.
You said around the tub but then you said shower, what is it?


----------



## Robdude (May 12, 2009)

26yrsinflooring said:


> Well.... sticker it is but there is a little more going on than that.
> 
> The thinset you have is a top quality brand, Mapei.
> If you are wondering how it is pronounced it is (mop-a)
> ...


Thanks for the post. 

I'm not sure what the correct term for it is - but it's a bathtub, with a showerhead. I think it's pretty common. I have a picture from before I started tiling/after I put up the cement board.










You can't see the showerhead - but it's up there 

So, in the future, in general - unless I have a reason not to get it - I should be buying the modified thinset for tile jobs?


----------



## Daniel Holzman (Mar 10, 2009)

You should purchase the type of thinset that is recommended by the manufacturer of the tile. It gets more complex if you use a bond breaker product such as Ditramat (manufactured by Schluter), since they have their own recommendations for the type of thinset, which may be different than the recommendation of the tile manufacturer. For example, I used Ditramat underneath my natural stone tile in the kitchen, and the recommendation from Schluter was to use unmodified thinset underneath the Ditramat, and modified thinset above the Ditramat. Interesting. I don't really know why they make this particular recommendation, however it is quite clear from their product information that the use of two different forms of thinset is recommended for my particular application.

As for your case, if the tiles stick, you should acquit..... and don't worry about it.


----------



## Bud Cline (Mar 12, 2006)

You have it backwards Daniel.
DITRA is to be installed to the substrate with modified but the tile is to be installed with unmodified.



> Hugh Scott/Indiana Floors: "The lack of use of the latex modified thinsets in tile setting has led to a flurry of failures in showers and flooring installs I blame this on Schluter Systems"


MOST all tile applications can be done with unmodified thinset without issue. There is nothing wrong with using unmodified thinset. The above statement is ignorance of the industry. In the case of Schluter...all manufactures of product requiring the use of thinset make their own recommendations about which thinset products to use - Schluter has that right also


----------



## Daniel Holzman (Mar 10, 2009)

I did indeed write the Schluter directions backwards. However, I did install the membrane in accordance with the instructions. Call it dyslexia perhaps?

I have no interest in getting in the middle of a fight over Schluter. I can say that $1.50 per square foot seemed a bit pricey, however the results seem to have been excellent. In approximately two years of install, there has been no evidence of movement, no cracking, in short no problems. Of course, the same could have occurred had I used a competing product, or possibly the results would have been fine with no membrane.

I found the Schluter directions very complete, including diagrams and explanatory text. They certainly did not explain exactly why they recommended both modified and unmodified thinset, but they are under no obligation to me to explain the theory of thinset. As for the OPS post, I stick with my original theory, if the tiles appear to have stuck, I would leave it alone.


----------



## tpolk (Nov 7, 2009)

I got in an argument with a guy the other day and my posts were deleted and was threatened with a one week kick to the curb hhhhmmmm guess i picked wrong argument


----------



## Scuba_Dave (Jan 16, 2009)

Guys, if you wish to argue about Mfg's take it to another board or other venue or you will no longer be welcome here

Its getting more then a little tiring going thru this every few weeks
Personal attacks will not be tolerated
Advertising will not be tolerated
Denouncing a product in a signature is ALSO not allowed
If you have a problem with a post, report it
If you join in with the bickering then you will end up being banned from the site as will others

*Last warning*


----------



## Bud Cline (Mar 12, 2006)

> I found the Schluter directions very complete, including diagrams and explanatory text. *They certainly did not explain exactly why they recommended both modified and unmodified thinset,* but they are under no obligation to me to explain the theory of thinset.


In the case of DITRA...the product must be glued/attached to the floor/substrate. To accomplish this with confidence a *modified thinset is used* because it has the properties necessary to bond the DITRA scrim to most common substrates as long as those substrates are not a form of plastic. The substrate will allow for some absorption of moisture and the air necessary to dry the thinset.

To install the tile atop the DITRA (especially porcelain ceramic tile) *an unmodified thinset is used* because it will dry/cure chemically and on its own without the benefit of air. DITRA and porcelain tile have a very very low absorption rate. [DITRA: 0% and porcelain: 0.5%.] The combination of the two will slow the drying/curing process tremendously.

The recommendations didn't start out that way and were added only after complaints of modified thinset over DITRA and under porcelain tile began to pile up. In some cases it can take weeks for modified thinset to dry over DITRA and under porcelain.

In my experience...I always use modified thinset for both areas and have never had an issue. I don't however complete installing tile at four o'clock one afternoon then return at eight o'clock the next morning to grout. I allow a few days between the operations. This is over a wood structure (only) with environmental controls above and below the tile installation. Installing DITRA over concrete below grade would be a different approach for me and in that case the use of unmodified thinset to install the tile would be a must.

Don't do as I do - do as I say, and that is to follow the recommendations of the manufacturers in all cases.

This may be somewhat confusing but the truth is...the instructions are clear and available to everyone.


----------

