Shower chair rail cracks after install

[JohnfrWhipple]

Today I found a simple question online on another tile forum. The fellow (Ken) is asking if the tile repair his contractors have suggested is a proper repair or a cheap band aid. He no doubt is worried about entire shower build and his brand new shower.

Lets look at the pictures he uploaded.

"Hi! I'm a homeowner who had his bathroom gutted and re-done ~six months ago by a large, reputable company, specializing in kitchen/bath remodels.

As part of this process, the shower was demoed down to the studs, new floor pan, new plumbing, new wallboard (waterproof, can't recall the product name) and tile. The tile consists of ceramic subways from floor up to a matching "chair rail", topped by glass subways to the ceiling. Two tiled wall niches were provided for using the same tiles.

Yes, it looks terrific, but six months later most of the chair rail tiles are exhibiting lateral hairline cracks on the lower side of the bullnose. The company stands behind their work, but their suggested repair consists of removing the cracked tiles and re-installing using sanded caulking, which will match the existing grout.

Does this seem a reasonable solution or is this a cheap and easy fix to a more substantial problem with the initial install? I'd appreciate any help and advice before I let them proceed. I'm happy to post pics after the requisite three posts, if that will help.

Thanks in advance," - Source *​

I suspect that the installer of these Chair Rail Tiles filled the back side of the pieces with thin-set. I suspect that the thin-set was mixed a little loose. And over time the thin-set has started to shrink to the point where it finally failed the chair rail detail.

Concrete shrinks when it cures. Thin-set should not be set heavier than 1/4". Had the installer on this job used a product like Ardex X-32 for these pieces or the pre-fill step. I'm sure her shower would be looking a lot better.

Should this fellow let his tile crew do a hack repair job on it..... HELL NO. They need to come out and get installed properly. Not installed with sanded chalking.

This flaw in Ken's shower simply highlights the importance of proper thin-set selections and proper applications. We do not know the brand of waterproofing used or if one was in place.

Another tile man on the other forum suspected that the chair rail tiles might have no thin-set filling the void. I suspect the later. And all of this is related to over water thin-set and too thick of an application.

In the tile industry there is a growing surge in Indent Fractures. This would be my guess.

On the flip side another sceneriao might be that the glass tile is expanding and causing stress on the chair rail. Perhaps the tile is installed tight to the ceiling with no room to breathe.

Maybe the glass tiles where not installed with the proper directional arrows considered.

Many scenarios.

 

[JohnfrWhipple]

It is important that backer boards get installed with blocking between the sheets. This will help prevent movement.

A properly prepped shower wall would see concrete board. Ideally WonderBoard Lite from custom Building Products.

​

If you do not see this level of blocking work on the shower walls framing. Your getting short changed.

 

[Sponsor]

 

[JohnfrWhipple]

A tile install like Ken has should also see a flexible thin-set used. When choosing a flexible thin-set you should first ensure a premium waterproofing material is used to waterproof the shower that allows for flexible thin-set.

Kerdi, Kerdi Board or Kerdi DS would be poor choices for the shower build above for example, since they do not allow modified setting materials with flexibility over their membranes. Using something like Hydro Ban Sheet Membrane, NobleSeal WallSeal or TS or even Ardex's 8+9 far better choices when one wants to use a premium flexible setting material.

 

[ShowerDude]

John, a great way to help reduce the chance of this happening. is to soak soft glazed ceramics in clean water prior to installing i then sponge off the excess. This helps the thinset cure slowly and reduces the chances of cracking as the curing thinset shrinks and starves for water.. My 2 cents. learned it from an old school tiler while i was an apprentice. A totally different old schooler that the one that tought me to cleat and recess my subfloors.!!!!!! wink wink.

always soak the subway's.....

also would have used a silicone joint as expansion from the glass to the charrail...

 

[Jadnashua]

Some things that John just doesn't seem to understand is that all mortars, modified or not, are somewhat flexible. And, when using something like Kerdi, or HydroBan sheet membrane, or pretty nearly any sheet that has a fleece on it, the thinset does not stick to the sheet, it holds by flowing around the fibers of the fleece then hardening during the curing process. The fleece to the membrane body offers far more flex than just adding a modifier to the thinset. And, the bond strength to a fleece covered sheet membrane is limited by the fleece's strength, which is far less than the bond to the tile. Bond strength to rigid surfaces is one thing, throwing a sheet membrane in between is a totally different thing and some people just can't seem to get their head around that and blast products with decades of successful installations from their lack of understanding. Also, if you look at some of the testing references in the tutorial section on thinsets, you'll see that the baseline for all of the tests is an unmodified, and that it outperforms some of the tested modified mortars, and this is when bonding to rigid surfaces, not a membrane, which gives you an even bigger margin.

Using an unmodified thinset without a membrane on many surfaces is asking for problems. Using one on a properly engineered membrane is not, and offers many advantages. People can point to bond failures on rigid surfaces with an unmodified under some conditions, but I've yet to hear of a bond failure with unmodified to a sheet membrane when the structure and install was done according to instructions. Can anyone point to a bond failure with an unmodified over a bonded sheet membrane? You just don't see them if you scan the internet, and people certainly like to complain...it just doesn't show up!

For the OP, the tile went to the ceiling and was grouted. This is against the TCNA guidelines which state all changes of plane should have an expansion gap (often, caulked, but a literal gap works as does an engineered expansion joint). Guess what, the weakest link broke. There are reasons for the industry guidelines...people and testing over time have found that there are certain ways to make things work, and when you don't follow those guidelines, you often (not always, which is why some people claim to know better!) have problems. The guidelines help to protect you from those 'what-if' situations, where all of the problems have to align to create a failure. No one person's lifetime experience can trump the aggregate industry's inputs and experiences that go into setting those industry guidelines. Working outside of them, and you're asking for problems. Won't always happen, but you're still asking for problems.

 

[Errant]

Sorry for commenting on such an old thread, but I will be installing a chair rail that continues into the shower/tub surround and want to make sure I do it right.

Should the void in the chair be filled or not? I'm inclined to think not, but I've never used it before. I'll be using Hardie CBU with Redguard on top. Dal tile ceramics subway above and below the chair, VersaBond thin-set. I'll use caulk between tub/tile and tile ceiling. Will I end up with the same problem?

 

[Jadnashua]

FWIW, most chair rail is made from a fairly soft tile, so on a wall, it will be the weakest link. Industry standards call for soft joints on all changes of plane (often caulk) to help prevent stresses on that joint from being transmitted along the wall or floor into the tiled structure. It is important to get your wall sturdy. But, I've not answered your direct question. I haven't installed enough of that to have long-term experience one way or the other. You might want to ask it at www.johnbridge.com where they specialize in tile questions. A gap behind it on a shower wall would give an opportunity for moisture buildup behind it which could cause color changes in the tile under the glaze. Some thinset can be applied thick enough to fill that easily, but most will have issues. Thinset applied thicker than design usually does shrink, and could crack a soft tile.

 

[Errant]

Thank you, Jim