Epoxy Grout Shower Floor

[RubenDog]

Quick question on grouting a shower floor using laticrete spectraloc pro. Do I grout all the way into the corners of the floor, or do I need to leave a gap for floor movement?

I'm concerned that if I leave a gap that water will gather in the edges and be prevented from moving to the drain by the epoxy grout. The tiles are travertine and the shower pan is kerdi over the foam tray.

Thanks!

[Tool Guy - Kg]

That's a "change of planes" in the corner and the epoxy grout should be kept out of the corner. That gap should be filled with a flexible high quality, color-matching sealant....like 100% silicone.

By the way, is this a Kerdi shower, or a traditionally built shower with a mud floor/pan liner?

[rjnebbo]

From what I have read here, is that if the whole shower is Kerdi (not just the pan) then you COULD grout the change of plane areas (corners) with the epoxy grout or traditional grout. The reason for this, from what I understand, is that the Kerdi acts as a support and thus limits the amount of movement at those joints (benefit from using Kerdi). There are many here that will grout rather than caulk anyways, then there are some that will caulk those areas regardless. Obviously caulking is the safe way to go.

Other questions I would ask myself would be; how well is the shower framed (sturdy) and what type of floor are you on... Mobile Home, raised floor, or on a concrete slab? Lots of things to consider. Are you in earthquake country?

By the way I would never want to just leave a gap, you would have to fill it with either grout or caulk with 100% silicone ONLY like Laticrete Latisil or GE silicone II. The Latisil can be purchased from the same place you got your Epoxy grout and they should have the color to match... The caulk is flexible and will move expand without cracking

Note: The epoxy grout will not crack.... so if there is flex, the tile MAY crack instead, as the epoxy is stronger than most tiles.

I am not a pro and these are things I have learned from reading here

[java]

Epoxy grout those gaps and forget about it.

[RubenDog]

Hmmm, two opposite answers, and one middle.


The shower is kerdi membrane. Two walls are kerdi over drywall and the other two sides have kerdi over hardibacker over 2x framing (tub and shower curb). The shower floor is 4'x4'. The pan is schluter foam.

If I grout the floor all the way into the corners will I have issues with cracking tiles? The tiles will be a mix of 2x2, 2x4, 4x4, etc with 1/8" grout and drain in the center.

Thanks again

[Brian@BC contracting]

Rube...I grouted w/ spectra all change of planes...and no issues yet! BUT, its only been about a month...Chuckle!
On serious note..Who was it that conducted a 90 pound stress test on the spectralock"nothing to fear" thread? The tile finally gave at 90 lbs before the spectra lock even fractured!!

Brian.

[MDK]

Yep, that was me that put weights on a tiled piece of drywall. It held 100 lbs of weight without breaking or cracking. 90 lbs broke it with the panel flipped upside down and the tile on the bottom side. The tile broke, not the grout.

Don't take any advice from me since I'm new at this, but I used Latasil silicone sealant on the inside corners of my shower. All changes of plane inside the niches were done with Spectralock Pro Grout though.

[Brian@BC contracting]

Mike...I actually showed your thread to a client in which we are using spectra lock in between some honed stone beveled caps on top of a stucco wall on the outside of his MTV "Cribs" style house. He was impressed as hell! Thanks for the "grout porn"... You sir helped sell a job

Brian.

[Tool Guy - Kg]

While what Bob said is true about some pros grouting the corners, we aren't talking about epoxy grout. We're talking about cement-based grouts. Epoxying corners will eventually bite you.

Everything else being equal, the corners in a tile assembly are relatively weak and cementitious grout will crack (in the corners) long before epoxy will. With enough expansion and contraction movement, something has to give way...the weakest part of the assembly. By making the corners very strong by epoxying them, the weakest point in the assembly may be in the field of tiles. If the stress overcomes the strength of the tile, cracking will occur in the field somewhere, creating a mess of a repair.

Will it "for sure" crack? That's a physics equation based on, among other things, how much thermal and moisture movement the tile assembly goes through. And the larger the "plane", the more movement...a 5' shower is more likely to crack than a 3' shower. So if you want to take your chances with a cementitious grout, your downside is a relatively cheap repair in the corner.....but the downside to epoxying the corners is a relatively expensive repair. The point is that matching sealant for SpectraLock is easily available and allows for the natural movement to occur so your tile job lasts a long, long time.

[Brian@BC contracting]

Tonto...Ill be keeping you all posted on my using spectra in the corners/change of planes on my last install....even 5 years from now with daily use...If it makes it that far w/o cracking. Our friend brian in san diego i believe used spectra in his planes in his shower and all good after 2 years. we shall see. Of coarse,i hope your wrong.

Thanks, brian.

[java]

I'm not advocating epoxy grout in the shower wall corners.

But down in the shower floor it is a non issue and a good thing.

I epoxy almost all my shower floors and have for almost 13 years. Never had a problem and the customers love it. easy to clean

And I have seen many years down the road and most of them 1 year after the install for end of warranty check ups in new homes and never ever had a problem.

[Tool Guy - Kg]

If all the variables that cause movement were easily available and easy to calculate, we could give a reliable answer for each project. But that's not the case.

Brian and Jason: In the Tile Forum/Advice Board, we're dealing with DIY'ers. It's long been our policy in the "shallow end" to stick to manufacturer's instructions and industry guidelines...and that includes not epoxying the "change of planes" at the corners. But you're totally welcome to bring it up and discuss it in the Pro's Hangout if you like.

[MDK]

Mike...I actually showed your thread to a client in which we are using spectra lock in between some honed stone beveled caps on top of a stucco wall on the outside of his MTV "Cribs" style house. He was impressed as hell! Thanks for the "grout porn"... You sir helped sell a job

Got a free T-shirt for that post.

Matching color Latasil in the corners looks great.

[timo]

jason, may I ask you a question, since you've got a lot of experience with epoxy grout on shower floors.

SpectraLOCK isnt' available in the colors needed; it lacks the Bone, Pearl, Oyster hues. However, TEC's AccuColor EFX epoxy does have these colors. I wasn't able to find anything on this site about the TEC epoxy grout. Have you used it? If so, any comments?

Thanks