Tiling Over Primered Plaster Walls [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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04-20-2008, 08:05 PM
I have old plaster walls with drywall compound used to fill in imperfections. This is a non-wet surface. I primered the entire wall. I am installing 12x18 travertine tiles using a modified thinset.

Will the heavy travertine be OK with the thinset over primered wall?

Should I rough it up?

Thanks guys

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04-20-2008, 10:17 PM
Hi Don. I'd rough it up a little, should be fine with the modified thinset. :)

04-20-2008, 10:21 PM
i've worked on and repaired a lot of plaster but never tried to tile over it. but i do have a good friend who is a master plasterer. he's restored buildings in DC and has a few souvenir tiles that lincoln walked on and i turn to him for info when i need it. he's told me that while plaster is a very good surface that after it is newly applied, if the building ever falls below 40 degress, the difference in the coefficient of expansion of the wood substructure and plaster will start the cracking process. over time it will crack more. pretty dismal forcast if HVAC is ever off between owners, etc. i do know that i've seen the entire wall or ceiling suddenly fall off in one big avalanche with no warning. makes you wonder about sleeping in old plaster-ceiling bedrooms. sorry that's not exactly tile related, but do hope the plaster/lathe/studs are all in good shape before more weight is placed on it, expecially if it is the old wood lathe nailed to studs.

i'd like to hear if others have had good long-term success tiling over OLD plaster. all the best,

04-20-2008, 10:29 PM

This plaster is layed over brick with wire mesh. It is very solid. Plasterers did do a really bad job on the straighness though. I had to do a LOT of filling for the large tiles that I am using.

04-21-2008, 09:00 AM
Thanks Davy

I am using Kerdi in the shower area. I have a niche with a curved top (outer and inner corners. How do I wrap this with the Kerdi - KERECK? Should I make cuts in it to turn around the radius?

Another quick question. What size notched trowel for the 12x18 tiles on wall and 12x12 on floor? Installing travertine. 3/8 fine?

Thanks in advance.

04-21-2008, 06:52 PM
Yeah, cut it anyway you need to, just overlap everything 2 inches and you'll be fine.

3/8 notch should be fine. I like to skim coat the backs of the tiles with the flat side of the trowel and use the notch side on the wall or floor. :)

04-21-2008, 08:01 PM
Cool, thanks.

04-28-2008, 04:18 PM
I have never laid a natural stone like travertine before. My brother (who is helping me) said that he heard that you should seal the entire tile (backside included) before you lay it. He said that this prevents color bleed through of the thinset. It seems to me that if you seal the backside, you will not be able to get the thinset to adhere to the tile as good. Any thoughts?

Also, the floor is 12x12 travertine. Using a 3/8ths notched trowel. Do you recomment back-buttering all the floor tiles?

Thanks for the help


04-29-2008, 05:06 PM
Help anyone?

Brad Denny
04-29-2008, 05:12 PM
Hi Don,
Sealer on face, not on back and backbutter is best. :)

06-25-2008, 09:10 AM
What kind of grout do you recommend for travertine? I have 3/16th joints. Going to use a sanded grout.

Is SpectraLOCK Pro epoxy a good choice?


Don :bow:

06-25-2008, 09:20 AM
Don, is your current grout question a continuation of April's thread, here? http://johnbridge.com/vbulletin/showthread.php?t=61974


06-25-2008, 09:26 AM
Yes it is.

Sorry. Should have kept it on the same thread.

06-25-2008, 09:44 AM
What kind of grout do you recommend for travertine? I have 3/16th joints. Going to use a sanded grout.

Is SpectraLOCK Pro epoxy a good choice?


06-25-2008, 10:09 AM
I just combined both threads, Don.

I've not used SpectraLock so can't offer any hands-on advice. With relatively thick travertine and 3/16" spacing, you'll need quite a bit although I don't see any square-footage numbers posted above for the walls and floor.

06-25-2008, 10:16 AM
What do you typically use for the travertine?

06-25-2008, 10:54 AM
Don, I use traditional cement-based grouts. Sanded for 3/16" spacing. Custom's PolyBlend, Mapei's Keracolor, and Laticrete's 1500 Series grout 99.9% of the time.

07-16-2008, 07:34 PM
I am wanting to use a StoneTech sealer/enhancer.

Is there a difference in protection in the water base and solvent base?

Is one or the other harder to apply and work with?

I have a relatively small area of floor to seal in a bathroom right now: 8'x8'.

BTW, I got the Felker FTS-150. Man, great saw!! Thanks to the threads on this forum, I got a great price on it.


07-16-2008, 08:39 PM
The Stone Enhancer is water based and for indoor use. The Enhancer Pro is Solvent based and for indoor and outdoor use. Lasts up to 5 years in the sun.

Both are wipe on-wipe off sealers. I would use the Enhancer Pro. The worse thing you can do is to let the sealer dry on the surface. Check the label, it has instructions, purty easy to do. :)

07-16-2008, 09:10 PM
What happens if it dries?

When re-applying after 5 years, or so, do you have to strip off the old sealer/enhancer or just apply on top?

Thanks Davy

07-16-2008, 09:18 PM
If you let it dry, it becomes a sticky mess. The floor might would need to be rehoned to get it off. The instructions say to let it soak for 15-30 minutes, then wipe it off. I would wipe it a little sooner, myself. It's usually not a big deal, no big rush to get it up before it dries. Although, I wouldn't wipe it on and go out to lunch. :)

After 5 years, (I'd probably go about 3 years) clean it well and go over it. :)

08-02-2008, 06:08 PM
I think that I have read that Versabond was OK to use to lay the kerdi. Is this alright? I know it calls for unmotified.

Also, can I lay the travertine over the kerdi with the Versabond also?

Thanks in advance. I'm just making sure that I am not making a big mistake!!


Brian in San Diego
08-02-2008, 06:20 PM

Although you are breaking the "rules" using Versabond to apply the kerdi and set the stone I, for one, think you will be fine doing so. I think JB would agree with me as well. I would use white for setting the travertine.


08-02-2008, 06:34 PM
Thanks for the fast reply.

Yeah, I used white on the floor. I am planning on using grey to set the Kerdi and white to set the travertine.

I just wanted to make sure that was alright. The Kerdi and Travertive are quite expensive, so I don't want to have to do a redo.


08-14-2008, 06:07 PM
When squeezing out the excess thinset from behind the kerdi, should you keep pressing with the trowel until you get no more mortar coming out of the end of the material?

I am concerned that I may have gotten too much mortar out from behind the kerdi. The guy on the youTube video sure made it look a lot easier.


Thanks in Advance :sick:

08-15-2008, 05:55 AM

08-16-2008, 06:35 AM
Bump for answer.

Brian in San Diego
08-16-2008, 08:38 AM

IMO you don't want to squegee it so hard that your face is turning red from the pressure you are applying. The object of the exercise is to get the fleece imbedded in the thinset. Trowel your "loose" thinset, comb it, apply the kerdi and smooth it out applying enough pressure to force the fleece into the thinset. Some thinset should ooze out from the sides. Once you've smoothed it all out, pull back the kerdi to see if you have achieved 100% coverage. If not, then you have to adjust the thinset or the pressure being applied to get the necessary coverage. Pulling back the kerdi is a one or two time event to get the "feel" for how much pressure to apply. Once you have that feel then pulling the kerdi back to inspect isn't necesssary or advised.


01-03-2009, 08:33 PM
Here are some of the pics after the walls were completed and the Kerdi was up. Notice the niche that I built (I'm proud of that thing).

01-03-2009, 08:36 PM
Here are some more pics.

01-03-2009, 08:39 PM
Starting to come together now.

01-03-2009, 08:48 PM
Ok, It's really getting good here.

Brian in San Diego
01-04-2009, 12:45 AM

That work looks fantastic! Congratulations on a job well done. If you aren't proud of yourself, I'm here to tell you, you should be.


01-04-2009, 09:16 AM
Thanks. That was actually my first tile job. I did some cuts for a guy doing my father's kitchen before, but it was nothing that extensive. This bathroom is also in my father's house. It sure did take a long time. I laid a floor heating system and floated that in first.

You guys on here were a ton of help. I really appreciate it. I was worried about messing up, considering it was high-dollar travertine.

To all you new tile layers out there I have one word of advice: Take your time!! Do not get in a hurry. This job was painfully slow, but it was done right. My first day of tiling, I only laid 7 tiles. It got faster. Just take your time and figure EVERYTHING out first.

Again, thanks guys!!

John Bridge
01-04-2009, 09:24 AM
First rate, Don. :)

01-04-2009, 09:36 AM
Thanks John, and thanks for this website. This is by far the best source for tiling information on the internet.

Now it's time to take a break before the next project. :fish2:

The wife is wanting me to finish out the basement. :blah:

There's always something to do, another project waiting in the wings.

07-02-2016, 08:48 AM
Its been 7 years and I'd be quite curious to know, how is your shower doing? any major issues? any failure of the kerdi or tile over the old plaster?