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Pocket door assembly needs stiffing for tile installation.

Posted by enduring (My Page) on
Sat, Aug 31, 13 at 12:24

Please help me with this issue. I have this exact post on the Bathroom forum too.

Current assembly
I feel I need to stiffen the walls more than the current plan accomplished. Tile will be on one side. I actually don't need to stiffen the other side but these drawings indicate that intension. So There will be tile on the wall that is oriented to the bottom. The walls are 6". They have 2x4 set on the sides with the notched out areas to recieve the 3/4" ply that is inlayed and screwed in place. There is still some flextion. I do not want to t take out the wall at the point. I have been wondering if the 2 methods I've shown below might be helpful. My carpenter thinks that with the CBU it will stiffen it up as is.

Option 1a -
Using wood glue and screws every 4" oc, set in 3/4" plywood on the interior side of the assembly. New ply is shown in green. I would do this by taking off the black panels shown at the top of the illustrated assembly "NORTH", while "SOUTH" panels are still in place. I would roll the glue on and stand up the new ply panels and scew in place. All while the re-enforced wall is in place, standing. I don't need to re-enforce the north panels as the wall is fairly stiff as it is for standard drywall application and usage. 1b - Take off the "NORTH" panels, mark the "SOUTH" panel placement within the stud space. Next remove the "SOUTH" panels and glue up, dry, and replace.

Option 2
Idea to put angle iron, full length, at the stud and ply intersection as shown in red. These would be either epoxy in place, screwed in place, or both.

If there are better ideas let me know. Thanks for taking the time to consider this issue.

Current Pocket Door Assembly- Plan View


Follow-Up Postings:

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RE: Pocket door assembly needs stiffing for tile installation.

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.


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RE: Pocket door assembly needs stiffing for tile installation.

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


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RE: Pocket door assembly needs stiffing for tile installation.

You can use the term "CBU" until the cows come home, or all of us become mind readers.

" I called Johnson Hardware and they recommended putting 3/4" ply over their pocket door frames."

And your reluctance to starting over would be..............?

The reason I ask this, is that in all probability, the ply is 5ply instead of 7 or 9, and use a vertical piece instead of stacked horiz. in the side walls. Further subjecting them to the potential of deflection.

Ther is a reason pocket door frames are assembled that way, the members oppose each other.


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RE: Pocket door assembly needs stiffing for tile installation.

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.


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RE: Pocket door assembly needs stiffing for tile installation.

" 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.


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RE: Pocket door assembly needs stiffing for tile installation.

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 into pocket door photo IMG_4824_zpsbfc62364.jpg

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)
closeup of steel strap 1/4

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:
inside of pocket door w/steel strap photo IMG_4878_zps050cbd55.jpg

This is the Bathroom side of the pocket door. Each stud is rabbeted out to accept the sheet of ply:
tile side of pocket door to bedroom photo IMG_4821_zps145eb18e.jpg

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.


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RE: Pocket door assembly needs stiffing for tile installation.

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.


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RE: Pocket door assembly needs stiffing for tile installation.

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.


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