Shower Project

[eagle4x]

My tile project:

(2) 4' x 8' shower walls
Backer: John Mansfield GoBoard waterproof foam board
Tile: 24" x 48" porcelain
Grout: Mapei Flexcolor CQ

I hate mixing thinset and the tile contractors quoted too much to do the job, so here's an idea I have that I'm requesting input:

Drill 2 or 3 holes on left/right edges with diamond hole saw blade, and then drill a hole 1/8" deep wider than original hole so stainless screws can be recessed. Also drill a hole in center top and bottom of each tile, and where shower diverter and head to be installed, install screws behind so trim plates will cover them.

The holes in the corner where the 2 tiles meet to be covered with inside corner trim (fasade schulter, covers 3/4" of each corner), and the ones in center top and bottom of each tile to be covered with grout that matches color of tile.

There will be (4) 24" x 48" tiles on each wall.

There will also be a shower bench and towel rack to be screwed in on one wall and a grab bar on the other wall which will give additional support.

Since the GoBoard backer is waterproof on front and back, do you see any problems see with this type of installation?

[Davy]

Hi Mike. Let me make sure I understand you correctly, you want to drill small holes thru the tiles along the edges? And those screws is all that will be holding the tiles up?

[eagle4x]

Hi Davy...yes that's right.

[cx]

Welcome, Mike.

First, you understand that your Go-Board will not hold those fasteners and you'd need to be screwing into the framing behind the Go-Board?

Second, you understand that Go-Board is only waterproof until you start poking screw holes in it, right?

Third, you think this drilling and screwing will be easier or faster somehow than bonding your tiles with thinset mortar?

I'm thinking I must be missing something about the reasoning here.

[Davy]

Also, I think you'll be breaking the corners and edges off of tiles when drilling. That will also take a lot of time.

Hate it or not, I would stick with thinset.

[eagle4x]

@ CX:

The GoBoard to be installed:

1) 2 1/4" RockOn backer screws 6" - 8" apart to the framing using a dimple attachment on my drill so will be slightly depressed when installed.

2) Screws and seams sealed with John Mansfield sealant made for the GoBoard.

3) 5" wide seam tape over seams using same sealant in #2.

According to the mfg., the foam board is waterproof if installation done correctly. This method is no different than installing other types of backer board with RockOn backer screws and then applying a waterproof membrane over the boards, and is actually more waterproof using foam board because waterproof membranes will fail over time, but waterproof the layers of foam backer boards never fail. Additionally, thinset is not waterproof.

I tested drilling holes in porcelain tile using a diamond hole saw with water and did not take a long time.

My reasoning for considering this is that I'm not experienced using thinset...from my previous use, it's difficult for me to get the right consistency when mixing and it's messy.

@ Davy:

The holes would be drilled 1.5" - to 2" from each edge and therefore would not be any breaking of corners.

I think will take less time to drill the holes in the tile than for me to mix thinset and apply it. If I decide to use this method, I'll try using a drill press to make drilling even faster.

[Tile & Stone Guild]

I agree with Davy. There’s a reason running 24x48 is expensive. Your walls would have to be 100% perfect for there not o be lippage. Factor in the tiles will most likely be bowed. I’ve done mausoleum work with pin and anchors, this isn’t the same.

[eagle4x]

Jeff,
I had to tear out previous tile (12" x 24") I started because the walls not plumb. Also, one negative of the foam boards is that they flex if walls not plumb. Because of that, I've considered instead of 1/2" foam board installing 1/4" plywood and overlaying 1/4" foam board over it so will be rigid and should not flex but not sure how well the heavy tiles would hold onto only 1/4" foam board.

I've spent a considerable amount of time fixing the framing and now the walls are perfect after tacking the boards on the walls and checking with my level. However, that could change after all the screws installed.

Your answer makes sense about problems with lippage using screws, however, couldn't lippage be compensated for by adjusting screw depth?

[cx]

Mike, I wasn't questioning your ability to waterproof your Go-Board installation, I'm pointing out that your waterproofing will last only until you then poke a bunch of holes in the waterproofed walls.

Ceramic tile installations don't like movement. No movement at all. Very sensitive to that. I think you're almost certain to have a little more movement in your mechanically fastened tiles than you would a properly installed tile with thinset mortar.

And the ceramic tile industry calls for a minimum of 95 percent mortar coverage on the back of tile in a wet area. The amount of water you'll eventually have draining down the back of your tile installation with your waterproofed walls might be significant. Whether it will be particularly problematic I can't say. Never tried that.

It'll be an interesting experiment and some of us will watch with great interest to see how it goes. But you'll need to promise to come back every few years after completion to give us progress reports, eh?

My opinion; worth price charged.

[Kman]

And I thought I hated mixing mortar.

[eagle4x]

@ CX, I forgot to mention that I would put some GoBoard sealant on the stainless steel screws before installing them and a dab on back of tile where screw holes, which should not diminish waterproofing of the board.

[Davy]

Sounds like you have it figured out, Mike. Let us know how it goes.

[jadnashua]

The trick to mixing thinset is actually following the instructions to the letter. That means carefully measuring the water, and a suitable drill motor and paddle, then mixing it the indicated time. Thinset consistency can change radically if it's not mixed properly from crappy to super smooth and easy to apply.

Spreading thinset does get messy until you get some experience, especially on a wall, and a ceiling is tough, but a good drop cloth helps.

For a large panel, you'll find a slant-notched trowel will make it easier to embed the tile properly.

I'm not a pro, but I think you're asking for trouble trying to screw those panels to the wall, and I'm not sure I'd like the look. Especially on a large tile, even though porcelain doesn't have a huge thermal coefficient of expansion, that might be a problem over time.

[Lou_MA]

I never thought mixing thinset or working with it was especially problematic. Certainly not to the point where trying an untested method would be my choice for ease of install or long term reliability.

If needed, waste $20 on a bag of thinset and 5 gallon bucket and practice making thinset. Is there some aspect of mixing it or working with it that’s causing you the most problems?

[jadnashua]

The most common mistake when mixing thinset is not mixing it the indicated time. You can't really go by looks until you've had lots of experience...use a kitchen timer. If your drill runs too fast, it can entrail too much air in the thinset. You need a good paddle so that it actually mixes things properly.