Design of home made shower pan

R

richard7761

Hi. I think I'm going to make my own shower pan by laying a cement base (amongst other things like linings etc).

The place of the shower is good inasmuch as it's in a corner point, where the beams on the end are supported by a wall nearby. So, basically, shower is to be on end of joists, which joists are, of course, supported on the ends.

Okay. Imagine two floor joists about 410mm (appx 16") between centres. Of course, topped with floor boards.

What I intend to do is lay on top of the floor boards a sub floor (say 3/4" plywood) of size 640mm x 975mm. Now, imagine the joists are running from a north to south (top to bottom) direction - the left side edge of the sub floor board will overhang the left hand joist (which will be under the floor boards) by 80mm. The right sub floor board edge will overhang the right hand joist by 100mm.


The question is, is there any need to do any additional joist work under the floorboards? Such as add any joist pieces perpendicular to the main north/south joists. Thanks.


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It greatly depends on what you are going to make the shower pan out of.
Example- A pece of 3/4"ply with tiles stuck to it would flex no matter much timber you put under it causing the grout to crack and let water through the result being a bigger cost layout than if you had put a proper shower pan in the first place.
 
I've been watching a video of YouTube:

http://www.youtube.com/watch?v=JNB8...st=PLx_Uhp4JZLtdQCTHdttKbqjkT-V5QWLT_&index=4

Basically:

* Floor drain is affixed to sub floor

* Overlain with tar paper

* Overlain with about 1" thick of cement

* Overlain with liner

* Overlain with "Mud" (cement?). Looks about 3" thick. (?)

* Overlain by the tiles.

Rigidity comes from the layers of cement and "mud" layer.

You are creating in effect a sort of stone shower tray/pan.

Perhaps there is a better video, a UK one.
 
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Here is my idea of what I'm trying to make. I want to use a linear shower drain for convenience, and I'm hoping it's alright to put a slope on the floor of the pan to direct water towards the drain.As you see in my drawing. The threshold of course encloses the water in the open end of the shower.

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That link I gave in an above post, I think shows an unnecessary complicated series of instructions for making your own shower pan. Certainly in my case.

My shower is bounded on 3 sides by walls, and with one open side.

First thing is to change a circular shower drain for a linear one to make the tiling effort a lot less onerous. One is seeking to engineer two gradients or even one - if possible.


As to the series of layers that you would lay down, well, this would be my list:

* You need the sub floor boarding. That is say 3/4" or 20mm plywood. Maybe MDF board would do.

* I think you may need a membrane on top of the sub floor board. Perhaps someone can comment on this. Would regular polythene sheet do?

* you need then to pour over the membrane some mortar to create the shower pan/tray. I'm guessing you would make that about 50mm thick. When dried that should be pretty solid and should not pose a problem for the tiles which will be laid on top of this. Of course you would engineer a gradient or two with this layer.

* If Mapei tanking kit will seal cement, then you paint this layer over the mortar to provide a seal. Or, you lay some other kind of waterproof membrane over the mortar.

* The final layer is to lay on the tiles. The issue is, can you put tiles directly on top of the Mapei tanking kit layer, such that they won't crack when walked on. If you cannot, how would you solve that. In the video link I gave, there are two layers of mortar, so that the final layer of the tiles tiles are laid onto mortar. I'm trying to pour just one layer of mortar.

Is there a tile compound that is waterproof, so you put that on top of the mortar, so that it adheres the tiles to the mortar and seals the mortar as well?
 
I think you might use this tiling cement on top of the mortar layer instead of the Mapei tanking kit. Because it will provide a more solid base for the tiles. I assume. But in might be same stuff as Mapei tanking kit.

http://www.wickes.co.uk/Waterproof-Wall-Tile-Adhesive-15L/p/166351


If all these sealing cements/products are flexible, then maybe tiles have to be laid directly onto mortar with regular tile cement?
 
Actually, I think I ought to avoid tiling the bottom of the shower pan, and fit a plastic base of some kind on top of the mortar. This avoids the issue of seeking ways to avoid tiles cracking for want of a firm yet waterproof base for the tiles to sit upon. There ought to be some plastic material I can use for the shower pan floor.

P.S. The biggest issue I see is getting a seal right under the tiles or whatever is the top surface. If regular tiles might crack, because they are on top of a water proof but flexible adhesive, then the obvious answer is to use a flexible tile or flexible surface, which is most likely of a type of plastic. That means layering the mortar with an epoxy glue sort of compound upon which the top plastic surface will rest. A plastic surface tiled or otherwise, should not crack.
 
There is a difference between tiles on walls and on the floor of a shower. Because you stand on the floor, put weight on it. That I why I think if you stick ceramic tiles to waterproof and flexible adhesive they may crack (I'm assuming they will). So, I'm thinking of using flexible tiles.

I've been looking at Mapei tanking kit. In order to use that on the floor I believe the floor would have to be plastered, or plasterboard. But, would it be problematic to stand on top of flexible tiles sitting on plasterboard?
 
As to layers I'm thinking this:

* Sub board of 20mm plywood or MDF.

* Layer of plasterboard (takes Mapei tanking kit and provides a seal)

* Another board on top of the plasterboard (So plasterboard can take weight)

* Layer of tile adhesive that is waterproof (probably flexible).

* Flexible tiles stuck on with the adhesive.

No use of mortar.
 

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