Fill gap around shower valve?

[ssbowtie1]

Hi all, the tile cut around my shower valve is slightly larger than the valve trim. Because of this, there will be some small visible areas around the trim, but removing and cutting a new piece of tile will be quite difficult so I think I will have to live with the visuals. However, since the hole is larger than the trim, the trim gasket will not cover the opening properly. Grohe recommends filling the gap with silicone, but due to the depth and width of the gap (about 3/4”) would filling it with backer rod and then silicone suffice or will I always risk leaking water behind the wall? The shower was waterproofed using felt paper and floating the walls.

Also, what brand silicone is preferred?

Photo attached, thanks!

[ss3964spd]

Hi Ian, is this project the same as that in your other posts?

Those Grohe shower valve set ups, while very nice, demand precision as you have come to find. MY initial thought is if you paid to have the tile installed you should demand it be re-done correctly to eliminate the gap.

If that just isn't going to happen I would strongly suggest you not attempt to use silicone caulk to fill the gap. Grohe's suggestion of using silicone between the circular plastic body and the tile assumes the gap to be filled will be covered by the integral rubber gasket of the valve body, with the edge of the gasket making direct contact with the face of the tile, thus creating the seal.

You won't have that. I don't believe there is any way at all one could get the silicone "flat" enough so that its surface is exactly in plan with the face of the surrounding tile. If I absolutely had to live with it I would use grout, and probably an epoxy or single component grout.

BTW, how many outlets are you running off that valve?

[John Bridge]

Hi Ian,

If what I'm seeing is a template/protector it is to be removed before installing the valve trim. I would remove it before tiling and allow the tile to overhang the hole enough to allow the valve cover to make the proper connection. The face trim on my shower is just screwed on. There is no leakage there. I don't have a Grohe though.

[cx]

Problem with that, John, is that apparently the hole we're seeing in his photo is in the finished tile surface. Not gonna be able to make it smaller, even if he removed the plastic plaster guard, without removing the existing tile.

I can't tell how much of a gap he's got around the valve, but it looks like a well placed hole and I'm surprised his escutcheon won't cover it. But I'm not much of a Grohe user, either.

Anybody know if Grohe makes "goof plates" for their common shower valves?

My opinion; worth price charged.

[jadnashua]

I've put in a few Grohe valves, and I'm surprised the cover plate is too small to cover that hole and seal properly.

If you can't replace the tile, sounds like your best bet is either silicone (ideally with color matching to your grout), or a remodel plate.

[ssbowtie1]

Hi all, thank you for the feedback. I’ve attached some more photos showing the trim piece installed. The gaps are quite small, but they are just outside the trim cover gasket, so they would be susceptible to water intrusion. And Dan, I’m running 3 outlets from the valve.

As Dan said, the tile installer mentioned that he could try to fill the area with a close color epoxy, or I can stick with the original idea of using some backer rod (due to the 3/4” depth) and filling the rest of the void with silicone, or I’m open to any other suggestions you all may have. The epoxy idea seems to make the most sense, since as Dan said, the trim gasket is supposed to make contact with the tile or a solid surface.

And if the consensus is to silicone, is there a particular preferred brand?

Finally, let this be a warning to any future users of the grohe smartbox, the tile gaps need to be quite a bit more precise than normal!

Thanks!

[ss3964spd]

Still my opinion, Ian, that if removing/replacing the tile isn't an option then filling that gap with an epoxy grout would be best. Filling the gap with backer rod first wouldn't hurt. I believe epoxy affords the best chance of getting the fill to be completely flat and in the same plane as the tile face, thus allowing the feather edge of the rubber gasket of the control knob assembly to contact the epoxy. Since epoxy grout will stick to itself, if it isn't flat the first time you can add some more.

Was the smart box extension cut off after the tile was installed so that its cut edge is even with the face of the tile?

For those who might be interested; Grohe's "Grohtherm Smart Control" set up is comprised of

• The smart box - to which the plumbing connections are made and is what you see in Ian's first photo.
• The valve body, which is inserted into the smart box and retained with 4 screws.
• The control knob assembly, which is also inserted into the smart box atop the valve body and retained with 4 more screws. It is the control knob assembly which has the integral rubber gasket that seals to both the inside diameter of the smart box and to the face of the tile.
• And finally the decorative cover plate, which just pushes on and is retained by a shoulder on the integral rubber gasket of the control knob assembly.

Somewhere in the installation instructions is the max gap specification between the OD of the smart box and the tile.

[Snets]

Ian, what about swapping your round trim for the square trim? That would surely reduce your "gaps" to 4 much smaller areas as opposed to a full circle.

However I agree, in your situation with mud-floated walls, I'd want the tile removed, mud wall patched and tile re-installed with the proper size hole. Assuming the valve had the mud guard attached, there is no reason not to cut that hole as close to the mud guard as possible - the mud guard is a template for the proper size hole and proper mounting depth. Your particular valve, according to the manufacturer literature, requires a 5-9/16" hole, and the outer trim is 6-1/4" so hole could have been 1/4" bigger than the mud guard, all the way around.....in my mind those are not super tight tolerances.

[ss3964spd]

It appears the square trim piece uses the same round control knob assembly (I think Grohe calls it a "mounting plate"), and therefore makes contact at 4 points; 12, 3, 6, and 9 o'clock. Unless the square trim piece is designed differently than the round one, aside from shape, it doesn't have any seals, so while it might hide the gaps, the gaps still won't be sealed by the mounting plate assembly with its integrated seals.

Yeah, 1/4" isn't exactly tight, except compared to what other trim plates allow.