# where tile backer meets drywall



## rtoni (Jul 18, 2007)

Hi - wondering how I should address the seam / joint where 1/2" backer board meets 1/2" blue board in a bathroom shower area. Side edges as well as where the backer board meets the ceiling. If the backer board wall is tiled completely (edge to edge) along that wall, do I need to tape these joints and if so how do I mud them (setting compound, durabond, thinset, etc....?). Thinking of a glass corner enclosure where the glass will be installed just short of the tiled end. 

I think the backer board manufacturer shows the special tape (alkali resistant?) using a light coat of thinset to set the seam, but how would this work on the drywall half of the equation?


----------



## rjniles (Feb 5, 2007)

This seam can be hard to cover. I try to bring the drywall so that it just falls under the edge of the tile. That way the seam is not an issue.


----------



## rtoni (Jul 18, 2007)

rjniles said:


> This seam can be hard to cover. I try to bring the drywall so that it just falls under the edge of the tile. That way the seam is not an issue.


thanks for the quick reply - so if I understand it (sorry if I'm a little slow on the uptake) I could fill in the tapered edge on the drywall board, and run the tile out to extend maybe a half inch or so beyond the edge where they butt together? no taping?


----------



## General (Dec 11, 2010)

rtoni said:


> thanks for the quick reply - so if I understand it (sorry if I'm a little slow on the uptake) *I could fill in the tapered edge on the drywall board*, and run the tile out to extend maybe a half inch or so beyond the edge where they butt together? no taping?


You shouldn't have a tapered edge on the drywall, the boards should be running longways (railroaded), not standing up. The edge of the drywall where it meets the backerboard should be flat. As rjniles says, if you run the tile over the drywall a bit you won't have to worry about making the seem look pretty, excellent idea.


----------



## rjniles (Feb 5, 2007)

As the General said you should have a butt seam not a taper (but it really doesn't matter as the tile will cover the seam). I still tape the seam with the fiber glass tape that I use on the backer board.


----------



## rtoni (Jul 18, 2007)

General said:


> You shouldn't have a tapered edge on the drywall, the boards should be running longways (railroaded), not standing up. The edge of the drywall where it meets the backerboard should be flat. As rjniles says, if you run the tile over the drywall a bit you won't have to worry about making the seem look pretty, excellent idea.


thanks all - I don't think this will be too difficult after all. I can tape the seam (with the backer board tape) and tile over it to cover it. 

you have me a bit worried - in my bathroom the drywall is run vertical - me (DIY) working alone I found it was easier to handle. I read a thousand threads here on hanging drywall and in my case I just went with what I (my back) could take :yes:. On an 8' square wall in such a small room it didn't seem to make much difference in the quality of the job (like I said, DIY) and it still means 1 joint to tape so I didn't think it was a huge deal. Hope this is OK. The backer board is also a full 4x8x1/2" (Permabase) so 2 of these could go in standing straight up in the corner (for a 4x4 corner shower enclosure) with no cuts - so that's how I set it up. So I do end up with a tapered edge but that's easy to fill or as suggested just tile over. Does this sound right to you guys..? thanks for the feedback....


----------



## General (Dec 11, 2010)

I like Permabase 4x8 sheets. But you have the open cut end down by the tub lip. I would keep it an 1/8" up off of the lip and silicone between the lip and bottom of the board. Normally you would run the boards horizontal and have the nice closed finished edge on the lip of the tub.


----------



## rtoni (Jul 18, 2007)

thanks General - I didn't really think about the cut end vs the finished side - but also probably wasn't very clear in my original post that this is just a shower enclosure - no tub - I'll be tiling it all the way from floor to ceiling. Do I need to do anything special at the floor / ceiling before tiling? Probably going to use the Schluter Kerdi product over the cement board - and maybe putting their poly shower tray down too. I believe they make a 4x4 tray which would be almost perfect. From what I read this system is supposed to be very good (waterproof) and not incredibly difficult to install...?


----------



## General (Dec 11, 2010)

rtoni said:


> thanks General - I didn't really think about the cut end vs the finished side - but also probably wasn't very clear in my original post that this is just a shower enclosure - no tub - I'll be tiling it all the way from floor to ceiling. Do I need to do anything special at the floor / ceiling before tiling? Probably going to use the Schluter Kerdi product over the cement board - and maybe putting their poly shower tray down too. I believe they make a 4x4 tray which would be almost perfect. From what I read this system is supposed to be very good (waterproof) and not incredibly difficult to install...?


I see, I recently installed a shower but I used a cast iron shower pan which gets installed the same way that a tub does, so I was sure to run the PermaBase horizontally. Your situation is different so I'll let the professionals give you the advice :thumbsup:


----------



## rtoni (Jul 18, 2007)

no problem - I appreciate the advice regardless - and once I get this new shower unit operational, I'll be once step closer to tackling my old bathroom - including a tub + surround - so the add'l info is helpful :thumbsup:

thanks again.....


----------



## II Weeks (Jan 6, 2009)

dont use spackle on that joint. Use whatever mastic you'll be using to attach the tiles to the backer board. Same with the other joints on your backer board


----------



## rtoni (Jul 18, 2007)

II Weeks said:


> dont use spackle on that joint. Use whatever mastic you'll be using to attach the tiles to the backer board. Same with the other joints on your backer board


thanks II Weeks - I believe the manufacturer of this board (permabase) mentions using alkali resistant tape and thinset for the backer board joints - I just wasn't sure what this would do on the transition joints / on the drywall side of the joint. Sounds like this is the way to go there too.


----------

