I've installed wonderboard on the 3 walls of a tub/shower but I'm reading conflicting reports on how to cover the seams between the sheets. On the horizontal seams I'm using fiberglass mesh tape and modified thinset (the same thinset for attaching the tiles). I was going to do this then let it dry and then start laying tile but I'm also reading that I should not do this step before laying the tiles but at the same time?
The two inside corners are another issue. Treat these corners like the other seams (fiberglass mesh and thinset) or silicone caulk the corners. I know once the tile is set these corners should not be grouted and should be caulked but I'm not sure about the wonderboard inside corners. Thanks again.

Hi Jsutherlin...

I use an alkali-resistant tape and modified thinset to set the tape PRIOR to tiling... allows me to make up for any slight imperfections or feather out an area that is not quite as square as I would like. The down side to this, besides waiting for all to dry, is that if you apply excess adhesive or make any mistakes in the application to the wall it can be trouble for you when tiling later. For example, some excess adhesive falls slightly prior to drying correctly, creating a bulge in the wall that even when tiled creates bump in the finished tile.. now you have a prolem!

Anyway, if you can keep the mud tight and controlled then taping the seams FIRST will probably be best as it will allow you to focus on the seams/corners first and then later you can focus on tiling.. not the seams!

I think this is best for beginners anyway... ;)

Let me know if want to discuss more.

MARK

Thanks Mark!

I think I'll do the taping then do the tiling after it dries. Any ideas on the inside corners (silicone caulk or tape and modified thinet)? Thanks again!

Mornin'

I would TAPE and modified thinset the corners as well...

After tiling you can caulk between the tub and tile and if you want... the corners. I don't caulk the corners after tiling, but I do caulk between the tub and tile with a COLOR MATCHED caulking. You can usually find color matched caulking at tile store or home depot even sells some now...

Let me know how you make out!

MARK

I disagree. If you apply tape with thin set, let it dry first, and then start tile installation, you will create high point. Your tile will create bump in that area. Install self-stick mesh tape over the joints and start tiling over it. You will press thin set through the mesh as you trowel thin set on the walls.

Caulking is for superficial installation. It doesn't stick well to pourous, cementous, products. In any case, in tile installations, caulk is used for repairs, not for new work. That's what you have Grout for. You should grout entire area. Mix grout with fortified additive to achieve good strength. Tile should sit 1/8" above the tub and tub should be filled up with water when grouting the tile-to-tub joint. Non-Sanded grout should be just fine to fill the seam. If you end up with wider joint, use Sanded grout of the same color as for rest of the tile work. But before you tile walls, make sure your tub sits on solid floor. Reinforce floor if necessary. Flexing floors are the reason why you get separations where tile meets tub. If plastic tub, set it on bed of light weight concrete.

Milo... I mentioned exactly what you did in my first post? Did you read my post?

And, as always... different strokes... huh? I have had great success using color matched caulking between tub and tile. I know tons of guys that do it my way and quite a few that do it your way. Both seem to have an overall good result, but my way you never see a crack between the tub and the tile... ever.

Anyway, I think we hashed this out a bit before. I will always welcome a different perspective... not that you are wrong... nor am I.

Have a good day!

MARK

Mark, caulking should be performed by somebody who knows what he/she is doing. Applying caulk by H/O will most of the time result in visually unsatisfactory result that is very hard to correct. Re-applying new coat over existing coat to correct previous application - will make your tile work look sloppy and eye-sore.

Prep-work is important so no crack will occur. Interior corner studs inside shower / tub should be bolted together and/or at least 3 - A35's Simpson stress plates installed in each corner. Well and professionally prepared framing around and under the tub will eliminate caulking.

In my region, we do not caulk new work. Caulking is considered retrofit and / or used in repairs. For some reason, grout in new construction doesn't crack around here :D .

Have a productive day!!

Milo

See Milo... that is exactly why I say you caulk first... otherwise H/O will end up trying to caulk over grout that cracks and with the mold/mildew that has already set into the crack between the grout and the tile the caulking becomes a black mess of mildew and job looks awful just a year later! Of course, I only recommend caulking between the tub itself and the bottom row of tiles.

When you caulk first there is no need to touch up the caulking if you installed it when there was no mold to get in behind the new caulking.

I don't, however, disagree with you on the fact that most people are not patient enough with caulking to make a really nice job out of it.

Hopefully jsutherlin will take his time and make a nice job of it for himself!

Seems a lot of things happen in my area that don't happen in yours... huh... :p? You are just killin' me over here... killin' me... ;)



MARK