You'd have been better off to have simply used a regular pocket door frame and screwed wonder board to it.

Wonder board is a cement board used as a stable base for tile.

However, you can now screw the wonder board to what you've already under engineered, and over built.

Snoonyb, I am going to be using CBU over the existing system, as I stated above, I believe.

If any one would like to give me any other feedback on this situation I would appreciate it.

This system may have been under engineered and over built as Snoonby proclaimed, but my first carpenter designed it to meet my need to create a stiff wall for tiling. I called Johnson Hardware and they recommended putting 3/4" ply over their pocket door frames. The carpenter came up with this as a way to make a strong wall. The ply is not one continuous sheet and may be part of the problem. Maybe in hindsight there should have been a regular stud wall placed there then a pocket door system added on the other side.

I have asked my new carpenter about this and he thinks that with the CBU it will stiffen it up. I have visualized using the ply inserts by taking the panels off, as I have explained above. Does anyone think that will help?

The amount of flexsion that I get currently is about 1/16" to 1/8" movement when I push real hard on the pocket opening, leaning my weight into it. I don't know if the jamb trim will help or not. The carpenter didn't think it would do much.

This post was edited by enduring on Sat, Aug 31, 13 at 16:19

CBU= cement board underlayment

I'd just add a couple more studs, or glue the ply in there. Glue with a good thick bead of liquid nail, screw in place. Use some washers or scrap wood with the screws to pull it all tight until the glue dries without going through the drywall.

" I called Johnson Hardware and they recommended putting 3/4" ply over their pocket door frames. The carpenter came up with this as a way to make a strong wall. The ply is not one continuous sheet and may be part of the problem."

Yes, this is the problem. The plywood needs to be a continuous sheet. 1" A/C ply would make the wall REALLY stiff, but only if the sheet is continuous.

Your carpenter reminds me of this cabinetmaker that works for me. Really creative guy. The rabet joints cut into the studs and the plywood panels inlaid so finely... All that fine joinery work so neatly concealled inside the wall, totally defeats the purpose of adding the plywood.

Just add another layer of 3/4" A/C plywood to each side of the wall. (IN FULL CONTINUOUS SHEETS) Then screw the cement board over the plywood, with a layer of thinset mortar between, to make the plywood and cement board one solid panel.

I guarantee the wall will be stiffer than a regular 2x4 wall after that.

Thanks Homebound and Aidan_m. The pictures I have included may be of no help but I've added them.

Homebound, my husband and I are working on doing what you have suggested. But first we put in a 1/4"x3/4" steel strap along the studs. See picture. Then if still needs more, we will insert 3/4" ply between, as well. All this inside of the wall.

Looking into the pocket:

Looking at straps. The studs that are mostly visible are the near side of the pocket, while the steel is on the studs at the far side of the pocket (hidden)

Aidan, I hear you about the detailing of a cabinet maker :) I like your your idea of the continuous sheet of ply. But if I am understanding you correctly, you mean sheath the entire area across the studs that create the pocket door. I can't do this with the current wall configuration because the space is built to 60" to accept my cast iron shower pan. I can add more ply between the studs on the inside of the wall by accessing the pocket from the other side.

The studs with the rabbets are the studs facing the bedroom and covering the actual studs that hold the plywood that faces into the bathroom:

This is the Bathroom side of the pocket door. Each stud is rabbeted out to accept the sheet of ply:

I posted this question on the John Bridge forum several days ago too. There, someone suggested that I see if a tile man can take a look and possibly apply a mud wall to the scratch coat level. He thought that would make it stiff.

So we are working on the steel strap business with possible insertion of ply panels from inside the wall, accessing from the neighboring room. Friday a tile man will be coming to assess the situation. I am most likely going to have him do the tiling as I have lost my nerve with these big tiles. Another feature that will help, I believe, is the frame of the shower that will house the sliding doors.

Again thanks Homebound and Aidan_m.

I just thought of an excellent solution: Fasten 3/4" steel angles horizontally across the outside of the wall.Then have the tile guy install the mortar bed over them, the 1" of mortar bed will cover up a 3/4" steel angles. Make sure you use corrosion resistant steel, cement mortar is an oxidizer.

Aidan, thanks, that sounds strong. I don't think I can go out an inch and still stay within the design of my shower pan. I could go out 3/4", I think. The tile I have is sort of thick. I will have to visit the shed where the shower pan is waiting and do some measuring.

Last night we got the rest of the steel in place, and it is very stiff, just a teeny weeny bit of flex. We did not put any ply on the inner surface at this time. That might still be done. The amount of movement may even be comparable to the amount of flex CBU flexes between typical 16"oc spacing, but I don't have a wall to compare.

The tile guy will be here tomorrow and I will see what he says about the wall and options. I will keep you posted.