Does Pre-Slope absolutely need mesh reinforcement? [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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Spurs Fan
11-09-2004, 09:07 AM
Great site. But, i found it after i had already put in my pre-slope without the mesh reinforcement. I basically followed an aricle in taunton press by Tom Meehan - Looked pretty good to me.

Then I read 'How to float a Shower Floor Pre-Slope' -- by Harry Dunbar who implies that the mesh is necessary or the pre-slope will not work.

I've also seen shower pan articles without a pre-slope, which doesn't make since once you see the pre-slope method.

Do i need to start over or can i add mesh to the final mud layer?


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11-09-2004, 10:52 AM
I assume that you are on a wood subfloor, not a slab or you wouldn't ask.

The preslope is simply a bowl for the pan. If the subfloor is sufficiently stiff, your preslope won't flex enough to crack, and even if it did, it would be trapped by the wood framing of the walls and curb so it wouldn't go anywhere. So it would still function as a bowl for the pan.

That said, I would re-do it if that's all I had done at the moment. Why? I need my sleep.

We don't recommend newbies using lath in the final slope. If not done quickly, the mud starts to skin over before you have time to place the lath and the remainder of the mud. This causes a cleavage plane to form in the bed and that weakens it more than the lath helps. If you wanted to use 2x2 welded wire (the bigger holes allow for better bonding between layers), you could probably do this, but again, it's not worth it.

Spurs Fan
11-09-2004, 11:07 AM
The floor is 1 1/8 inch plywood that is glued and screwed to engineered trusses. The mortar bordered by treated 2x4s with a layer of thinset underneath. I've already put down the liner and am ready to add the lower backerboard and then mud the shower curb and final mud on top of the liner.

As far as strength of the floor goes my architect said i could put tile directly to the wood in the rest of the bathroom. I'll probably put down 1/4 inch backerboard anyway after reading this forum.

11-09-2004, 11:32 AM
What's the spacing your your floor joists? Backerboard can't be used if the spacing is over 16 inches.

Spurs Fan
11-09-2004, 12:06 PM
The spacing is 16 inches. The trusses are engineered and I was told i could put anything up there but a library. The area where i would use the backerboard is only about 80 sq. ft.

11-09-2004, 12:17 PM

John Bridge
11-09-2004, 06:17 PM
Hi Fan, :) Give us a first name.

I agree with Bob. It's not much to re-do. The lath will give you peace. ;)

11-11-2004, 08:55 PM
Hi Spurs fan,

I followed the same article that you did and put my preslope in without the mesh, put my 15lb felt down, then the pvc liner with the Oatey drain. My leak check went perfectly but then I found this wonderful web site. After much deliberation and handwringing I decided to tear it out and start over again (this time it will be with Kerdi). I cut the 2in pvc underneath the drain and the entire liner and drain lifted out without any resistance. Then I chipped my preslope out with hammer and chisel. It came out in big chunks without much trouble (I had let the thinset dry before putting the mud in since I didn't know any better). The whole process took about 45 minutes and you wouldn't believe how well I slept that night!

Tomorrow I hope to post a pic on my own thread holding a slab of the old preslope and liner and drain.

If anything I waited way too long before taking it out.


11-12-2004, 11:03 AM
The pre-slope you guys are refferring to here is the slope under the liner that causes absorbed, water to find it's way to the weep holes in the drain, right?

I built my slope into the floor using long cut shims every 2 or three inches and then screwed the ply down and bent it. In my case I had to add an extra skin of 3/4 ply and was able to create a very strong floor, sloped at a 1/4" per ft. Is this gonna be alright?


11-12-2004, 11:08 AM
Should be fine. Don't do it again! :D

11-12-2004, 11:37 AM
Spurs Fan, Your architect would be wrong!!
With your situation(plywood glued and screwed directly to your joists ),any installation directly on that plywood has a very high percentage of failing.Your architect should bone up on his TCA methods before handing out tile advice.His is a common error among architects and builders and death to Tile!!.
Its just not that big a book.
On the brite side,had you installed tile on your architects advice and it failed you would have had him by the short & curly's.They never learn :D

Spurs Fan
01-03-2005, 10:59 AM
Thanks to all on my questions about the shower pan liner. I have some more questions that i'm sure will get some expert answers.

First, the name is Ray.

1). Does it matter whether i do the floor or walls first. With the tile i have it would be better to do the walls first and then the floors so the edges of the floor tile will be visible along the edges of the shower floor.

2). Sandless grout. The salesman at Agent Orange (HD) told me if i use the 1/8 inch spacers i could use sandless grout, which he thinks is better for showers. Any opinions on that out there?

3). The shower ceiling is sloped so I will be tiling the ceiling. Any suggestions on doing this? I was planning on making the grout a little thicker so the tile would set up faster. Do i need to support the tile with a plywood brace overnight or anything like that?

01-03-2005, 08:13 PM
Hi Ray,

1. I do my walls first then butt the floor to it. Others round here do the walls and leave out the bottom row and make it so the floor tiles slide under the wall tiles. Either way will work.
2.Again, doesn't matter, 1/8 joints can be filled with sanded or unsanded. For tile sanded would be easier to do and would allow a little more grip on the floor.
3.I'm not sure what size tile you are using, 2,3,4 and 6 inch tiles will be easier to install than anything bigger. Sometimes I'll use the same size on the ceiling as the floor, something small. You can stick the tile right to the sheetrock on the ceiling if it's high enough not to catch water and it's not a steam shower. Alot of times I'll use CBU up there. Shouldn't need a brace. :)

Spurs Fan
01-26-2005, 01:04 PM
OK, i've tiled everything and am ready to grout. I've got a couple of questions before i start.

1). The shower drain - Do I glue with PVC cement or just use teflon tape and then grout. I'm guessing it should be glued.

2). Grout. What first? Ceiling, floor walls?

Thanks again for all the help. This project is turning out great. The slope may be a little steeper than a pro would have done it, but it probably won't be noticiable to anyone but me.

01-26-2005, 01:18 PM
1) If you're talking about the threaded part that houses the hair strainer, then you don't glue, and you don't need teflon tape either. If you're talking about something else, then I dunno. :D

2) Grout is messy, so start at the top and work your way down, cleaning up any stray thinset as you go.