Drywall around tub/shower

Two questions:

1.) Is it necessary to tape and bed the drywall (greenboard) before you install ceramic tile on top of it?

2.) Can the greenboard sit on top of the edge (on the very top of the ridge that curves up) of the tub or does it need to be hung just above it (no contact at all).

Thanks!

 

1) I would use concrete board instead of green board. All seems should be filled with mortar and the non tapered seems taped as well.

2) The wall board should overlap the tub lip with a 1/2 inch gap. Fill the gap with clear silicone caulk to the depth of the wall board. Then, after the tile is installed and grouted, fill the remaining space with white silicone caulk.

 

Hello kdr0919, welcome to the forums.

What exactly are we working with here? Is this a tub/shower prefab unit and you're planning on installing tile above?

You can get away with the greenboard, it's done all the time in tract homes, but if I were doing it , I'd use cbu if I was planning on setting tile on it. I can tell you that 1/2" greenboard is routinely installed so it lays just over the nailer flange on a one piece tub/shower unit. If that's what you're doing , you don't really want it resting on the flat surface at the bottom of the nail flange, otherwise water might be able to wick up the edge into the wall.

Hope that help ya out, post back if you have more questions.

 

This is a "regular" tub with a shower and existing ceramic tile around it. It is 24 years old and was starting to rot around the faucet, so I ripped it all down and I'm ready to replace it. The existing wallboard was not waterproof. Maybe they didn't have greenboard or concrete backer board in 1979?

Thanks for your help!

 

There is nothing wrong with using the greenboard to back your tile. Don't let it rest on the lip of the tub but it should overlap the top part of the flange in question. Fill the gap with silicone, clean the edge flush to your greenboard. Definately tape the corners and consider galvanized nails or other non-rusting screws (although regular ones work just fine) and tile as usual. Seal the base of the tile at the tub with a nice clean white silicone bead and you are set.

If you are doing any plumbing repair, for God's sake make sure all of the fittings are secure before you seal everything up...although it goes without saying, you have no idea how many of these I've been called to fix up after the fact....

Hope this helps.

 

Concrete board is the way I would go. you get much better adhesion and is more forgiving to DYI. You won't be sorry you used it.

 

Green board is no longer acceptable in wet areas and shouldnt be used in a tub surround. Use cement board.

 

At home inspections I frequently encounter failing tub/shower installations due to the use of water resistant (W/R) gypsum panels AKA "green board" as a tile substrate.

If someone is skeptical about this, I direct them to the USG web site, here's what United States Gypsum (the maker of "Sheetrock") says about W/R drywall, and why USG recommends the use of a cement board product instead:



Thus the USG recommended application matrix:



- Selecting Water Resistant Interior Panels

When asked for suggestions about how ceramic tile in a tub-shower surround should be done, I direct clients here:

Substrate and ceramic tile installation for walls, floors, countertops and wall shields

and here

Tiling Installation Systems: Tile backerboards, mortars, mastics, grouts and accessories that work together flawlessly.