Let me make sure I've got this right. You want to attach the chair rail to the edge of the durock and plywood from the top, as well as the plywood skirt that's been sealed with polyacrylic?

When the CBU is attached to the ply base, during that phase I'll usually fold over a strip of expanded diamond mesh to cover the plywood edge. I'll bed that with mortar, then later use a highly modified thinset to attach the edge pieces. For the thinset since you're in the Custom family, the "highly modified" would be FlexBond.

But you're beyond that stage.

It's the flat and flush edge of the plywood top that has me concerned, for with it being flush, any modifications done to the edge will bulk out the grout line between the edge pieces and the tiled top.

You might have to just go with what you have.

OK, when you ask it like that... actually, I made a small error (well, we've made many errors, this not withstanding):

There is 7/8" of tile edge and hardieboard edge flush with the side panel that, yes, is already finished, making about 1/2 of the chair rail on the finished panel and 1/2 on the rough edge to adhere.

So... rather than focus on how I got here to this question (8-I realize I will need to rough up the area of the panel that I want to adhere the trim pieces onto at the least.

How's about that PL poly construction adhesive?

Mongo, I was artfully clarifying (and running up and down the stairs) when you posted, please take a look above and see if you have any suggestions.

Bill, any thoughts?

Bill, any thoughts?

Nothing I'd warranty, and it certainly wouldn't be any kind of construction adhesive. If you take the finish off the plywood where the chair rail will adhere, you might get away with using Kerabond/ Keralastic. That's what I us when I'm setting over plywood.

Thanks Bill; I guess something was bound not to be well thought out- at least it isn't the shower pan or other disaster area. Hey, at least we are not paying someone else to do a stinky job ;-) We can do it ourselves for free! I have my dremel all set to go and I will get the finish off (I really don't know why I didn't think about that when I started finishing it?? I have been a little overworked at my day job).

I may use some mesh tape and get a skim coat on the tile edge before putting them up, unless I get some more cringing posts... I have room to increase the grout line a little there.

The rest of the bathroom exceeded my hopes, is otherwise structurally well done, and esthetically wonderful. Thank-you guys so very much for the advice and guidance- we couldn't have done it without!

Obviously I'm not the pro here, and we did our bath before I discovered GW, but I used construction adhesive to glue the chair rail pieces to the plywood panels, then grouted between the deck tile and the chair rail. It has stuck solid, no problem. If I was worried about lots of splashing and water it might be a different story, but Mr. Weedy and I are sedate bath-takers. :-)

Weedy- thanks, I thought I had recalled both you and another poster attaching them similarly... I bought some flexbond, I think it should be reasonably "adhesive". I am going to try one piece this weekend first just to make sure it seems to adhere before I do the whole thing. DH gets a kick when I screw up anyway, so he can be the one entertained for a change!!

Hey, pro or not, if it's not electrical, plumbing, showerpan, even unorthodox techniques can be effective. Since I didn't do it quite correctly, I will do my best at this point, and if it doesn't work, the worst thing is I will try a different approach.

Appreciate the post!!!

OK, I tested 2 pieces with the flexbond, they stuck, then I mounted all the rest and all went well.

Actually, I wanted to remount one piece, and tried to "gently" get it off once it had cured... it wasn't going anywhere.... so I am optimistic that all of them will cure nicely!!

Thanks!