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Replacing Shower Tile... Can I Reuse Cement Backing Over Wire Mesh Behind Tile?

24K views 39 replies 5 participants last post by  MetalMan8008 
#1 ·
I am starting to remodel one of my bathrooms and will be replacing the tile in the shower. Just demo'd it yesterday. There's a cement backing laid over wire mesh underneath the tile once I removed it all. The tile came off pretty easy once I figured out a good method. A few areas of the cement chipped off, mainly at the corners and near the bottom. Otherwise, most of he rest of it looks pretty solid. By the way, the house was built in 1964 an is in southeast Michigan. Yes, I plan on replacing the shower pan too.

My question is whether or not I can reuse that cement backing by simply patching up the areas that chipped off. Is this possible? Patch the areas that need it, smooth out the surface as much as possible, apply thinset and hang my tiles over that?
 

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#11 ·
Yup it's drywall, not plaster. I just tore the rest of the mud down, down to the studs now. The house is in north Warren.

I'll be adding a recessed light above the shower (hopefully, damn beam running right across the center of the ceiling though above the shower, not sure how to center the light now), replacing the vanity, tiling the floor, painting the walls, etc. So I won't be doing much else with the shower at the moment, but I'll check back with you guys if I have any questions as I get into it a little more. Thanks for the help.
 
#22 ·
MetalMan,

The subfloor looks a little rough but some of the discoloration may be from damp tarpaper. Any rotted or soft wood needs to be replaced of course. You can decide to remove all the planks if saving ¾" in height helps, or install 2 layers of ply for more strength. If you replace a few planks be sure to find the same thickness. Those look like 1x6" which measure ⅞"x 5.5".

I agree with some of what Greg says, except him suggesting to use ....
gregzoll said:
replace those sections with outdoor rated 3/4" Plywood.
That implies and you may think to use pressure treated ply, which would be wrong. I'm sure he meant to say "subfloor grade" ply, which is t&g and the plies are bonded with waterproof glues. Might be called exposure 1 or similar. You could also use OSB subfloor. If the planks are removed, you need t&g, otherwise square edge if ok.

I also do not recommend that anyone try this;
gregzoll said:
.....taped all of the joints so that none of the mud fell on the Laundry area, which sits under mine. You can get by with using caulk between the joints to keep any mud from getting through, when you go to lay the Concrete Backer or other material if you are tiling.
The above method is not Kosher. You always need to install min. ½" ply or OSB over planks. Planks are too unstable even if you can figure a way to keep the thinset from falling through.

All CBU's for floors MUST be set into thinset, fastened and taped ......no exceptions.

Jaz
 
#2 ·
There's no point in keeping that wall mud and trying to repair all that's bad. You're also going to replace the fiberglass pan I imagine, perhaps with tile. Take it all to the curb and start over.

Think about it then come back with new questions.

Jaz
 
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#6 ·
Thanks for the reply Greg. I can't expand it because there's a staircase going down to the basement on one side, and the kitchen is on the other side. There's simply no room to expand it. It would be nice if it were larger but all the homes in this area have the same size bathrooms so it's not really an issue for me. It's a second bath anyway that I never use.

It's a single family home, not an apartment. It's not a brick wall behind it either, looks like the mud and wire mesh is laid over drywall.

I have been doing a little more reading on this and I hear some people saying to rip down the mud and mesh, and others saying it's fine and just reuse it. It just seems like so much more work to rip all that down when I have 95% of what I need right there already. If there it's not possible or recommended to reuse what I have, can I ask why not?

If I do lay my tiles over the existing mud/mesh though, I don't know what I would do at the top of the tiles where it meets the drywall. The old tiles were curved at the top, since the mud sticks out 1/2" or so past the wall itself. I plan on going with larger tiles (maybe 12" squares), I doubt they make them curved like that. If I were to reuse the mud that's there already, how would I overcome the fact that the mud stick out 1/2" or so from the wall, and get the tiles flush against the wall at the top?

I'll wait for JazMan or others to chime in again on this.
 
#7 ·
MetalMan,

Next time you remove 50 year old tiles, plan on removing the substrate and tiles in one operation. Now you've spent extra time removing just the tiles and of course are reluctant.

Sure, it's posible you might be able to patch what's there, but it would be easier and better to rip it out. It'll make replacing the shower base easier, if you decide to go with a plastic pan again. I see cracks in the corners and there's a good sized chunk missing. I can't tell how solid the remaining mud is.

The reason the mud sticks out past the drywall next/above it is because that's the normal way to do "mud" work. They used "mud-cap" to finish the ends. (A4200) You could remove the drywall behind the mortar and replace with ½" concrete backer and therefore the shower is 1" wider too.

If you wanna patch, it can be done if it's still structurally sound, and I mean everywhere. If you say it's solid except..........that's not gonna work well, probably. This is assuming you can replace the base easily.

Lots of variables especially since we don't know your skills.

Jaz
 
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#8 ·
Damn, it's never easy when doing this stuff. Alright so now I gotta rip out that mud and bring it down to the studs. By doing it this way though, taking it down to the studs and putting up the backer board and all that, at least the surface will be flush with the rest of the wall then and I don't have to worry about the mud sticking out past the wall and the curved top tiles then, correct?
 
#9 ·
Probably. Since the house was built in '64, you probably have drywall and not plaster, right?

Which city are you in? It's never as easy as people first think, there's a bunch or steps to do and most important are the ones that don't show after the tiles are installed, especially a shower.

We'll spring a few things on you that you may not have considered. Like waterproofing. Have you researched how to build a shower much? And, don't assume the studs are all in plane and all you gotta do is screw up concrete board.

Jaz
 
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#12 ·
I would scab in a piece of 2x4, unless you get one that has the brackets that allow you to slide it to center. The other choice is to use a Retro fixture and put it in after the Boards go back up.

I used GP's DenseShield when I tiled my floor. It is a lot easier then working with Cement board. You can get it in 1/2". I would pick up a 2x8 for shims to adjust for any variance in the wall. You would just rip the strips off. Otherwise use Lathe for full length shims.

If you are doing a cent fan. Use a remote motor unit, so that it is not that loud in the shower.

Post the before in the project forum, along with mid to finish. My Bath remodel is buried in my attatchments on my profile. I had to rush to get my shower/tub up and working in 3 days, so it was a cheap surround.

Wife leaned on the wall and her hand went right through, because the Gyprock had water whicking throw from the grout cracking from a bad wall tile job.

Never again am I going to rush a Bath job again. My body paid for it after I got done two days after the tear out.
 
#14 ·
Ripped the shower down to the studs and have the shower pan out. I was planning on tiling over the old tile but there was a lot of hollow sounding tiles when I tapped them so I ripped up the tile too. The corner next to the shower and in between the toilet , the mudbed there is cracked in two spots. The mudbed itself is in good shape everywhere else but removing the tile near the shower caused a lot of damage to the mudbed (these tiles were attached much more securely here than the rest of the floor) and I don't think it can be repaired. Especially around the toilet flange. Bummer. I don't have pics at the moment as I am at work, but I am pretty sure the answer is going to be to rip the mudbed out.

The subfloor is wood slats. There was a small leak somewhere underneath the shower and there some stains on the slats but it's not rotted from what I can tell. It's solid and you can't push a screw driver into the wood. However, I don't know what the rest of it looks like below the mudbed yet. In the basement below, there's some stains on the wood but none of it is rotted when viewed from underneath.

I REALLY don't want to replace any of the wood slats on subfloor. I would think that if the water didn't rot the wood and compromise it structurally (just stained) then laying 1/2" or 3/4" plywood over the slats then thinset and lay the cement backer board down would be good, right? The current mudbed is 1", so if I do 1/2" plywood and 1/2" backer board I should be pretty close to the same floor height as before.
 
#18 · (Edited)
As long as that subfloor is not soft and rotted, you leave them. Otherwise cut them out with a shallow depth on a smaller sized Circular Saw. You can rent them from the local rental place or Home Depot. Then replace those sections with outdoor rated 3/4" Plywood. It would be hard to get Southern Pine or Salvaged pine to replace those areas.

Wood that gets that old, becomes like Iron. When I did my bath, I went through and used epoxied Deck screws to pull the boards against the joists. Then went down and taped all of the joints so that none of the mud fell on the Laundry area, which sits under mine. You can get by with using caulk between the joints to keep any mud from getting through, when you go to lay the Concrete Backer or other material if you are tiling.

My other post, I actually had just gotten up and was still half asleep when I posted that as an open thought, without catching all of the post.

I did the mud under the DenseShield, because I wanted it to be solid, even though it was getting screwed down. I had a couple of areas that were smaller then I expected, because of the floor area of my bath and close the closet drain is to the bath tub, which I had to cut one piece small for that area.

My floor will end up being one solid piece if this house ever comes down. I made sure that the floor was not going anywhere.

I did go around the perimeter of the floor and caulk between the tiles and the bottom plate, so if the tub did flood, I wold not end up with water getting between the tile and the sub-floor.

 
#23 ·
Thanks for the reply Jaz. I'm glad you chimed in because I had already bought a sheet of 3/4" pressure treated ply to replace the planks. The signs at Lowe's describing the purpose for each board and differences between them were terrible, they provided zero help in choosing the right board for the job. So I'll take that back and exchange for OSB exposure 1. If I remember right, those OSB boards said something like "wall/roof" and not floor so I skipped over them. I looked at every sheet of plywood in Lowes for a good while and none of them mentioned anything about being subfloor rated from what I recall. I was looking for that.

I was going to replace a couple of the planks instead of the entire subfloor but I couldn't find the right size planks and unsure about the type of wood to use. The planks are 5.5" x 3/4" thick, eastern spruce. All I saw at Lowe's were 1x6s, which would be too high in order to match the exact same height of my planks. Although at this point I am prepared to replace the entire darn subfloor, I was going to replace only the sections of the planks that are damaged but I had a question about how flat the first subfloor layer (sitting directly on the joists) needs to be. My solid planks are still cupped and warped a little, and a bit squeaky. Even if the first subfloor layer is not completely flat, wouldn't a 3/4 layer of ply above that provide a pretty solid and flat surface to tile on? I know the right answer is probably no, just tear it all out and replace everything, but I am curious about how flat the first subfloor layer needs to be below my 3/4" ply and cement backer board.

The plan for now is to have either planks or(probably) 3/4" ply for the first subfloor layer, then 3/4" ply on top of that, then 1/4" cement backer board. This should get me to the same floor height I had before, to meet the toilet flange. Yes I would definitely plan on thinset, taping and fastening the cement board to the ply below. I'm assuming both the subfloor layer replacing the planks and the next layer of ply on top of that should be OSB exposure 1 then, right? And I bought deck screws to fasten the plywood to the joists where I'm replacing the slats, does that sound like the right fastener for the job?

Now to jump back to the shower. My old tile didn't go up to the ceiling, there was a 2 foot section of drywall between the ceiling and the top of the tile. I'm tiling all the way up to the ceiling now. I have a couple questions about the edges of the tile and whether or not the tile can overlap the backer board and sit on some drywall too. It appears my old tile was doing this at the edges of the shower tile. As you can see from the picture below, where the drywall ends and the mudbed for the shower tile begins (where it used to be anyways), the old tile was overlapping and was set on the drywall. I assume it's ok to do the same thing and tile all the way to the edge of that 2" strip of drywall. Would this be correct, or do I need to tear that strip of drywall out and replace with backer board as well? Same goes for the section of drywall running across the top of the shower, I will be tiling that too. Just curious if that needs to be cement board as well or if that can just be tiled over the drywall since it's a small area. I know I should probably just replace it with cement board but I am curious and just want to know what can and can't be done for the future.

Also, what are your recommendations for waterproofing the area below the shower pan and the shower walls? There will be no benches or horizontal areas in the shower other than maybe a soap holder somewhere on the wall.

Cement board - Let me know what you think about these choices. For the floor I was planning on using the 1/4" hardie baord. Looks easy to work with and light weight. For the shower walls, 1/2" durock.
 

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#24 · (Edited)
Correct Jaz on what I meant. I always forget that some consider Subfloor or outside rated ply as PT.

The tape was placed underneath on the Basement side, not on the Bath side. It was just to keep any mud that was applied for the DensSheield to be placed to help make the floor more solid. Proper taped joints before I tiled.

If I had laid 1/2" down instead of 1/4" DenseShield, It would have been too high, since our wood floors are the Veneer style that they started to use towards 1940.

All 1x6's were screwed down with epoxy deck screws, so that they would not move. All of the rooms in our house have floor bounch from the nails not holding after 80 years.
 
#25 ·
If you're going over the planks you don't need t&g, but I didn't find any exposure 1 that isn't t&g. So, use this OSB; http://www.lowes.com/pd_12218-99899...torStoreBean@2d612d61]&pl=1&productId=3602846 *or this ply; http://www.lowes.com/pd_12249-99899-NA_1z0ry6d__?productId=3602910&pl=1

On the planks, 1x6" is what yours are called. Today's 1x6 are 3/4x5.5", I would be shocked if their 1x's are actually 1". I thought your old planks may have been closer to ⅞", maybe not.

If the planks are cupped, you need to screw then down to remove the curve. It sometimes can be done. For ceramic under 15", the floor must be flat within ¼" in 10' and 1/16" in 12". When measured from the two high spots. Adding plywood will not change the level plus that little hump will get larger. ¾" ply will fix a slight dip though.

Ideally the toilet flange should sit at the level of the finished floor. It can be a bit lower and a thicker wax ring used, or other remedies. Therefore, you can use a thinner underlayment grade exp. 1 if it fits better. Deck screws are ok since they're rust resistant. Ring shank nails are good too. Be sure to fasten the underlayment to the subfloor and do not use xtra long fasteners to hit the joists. avoid the joists. Hit the joists with screws before the underlayment.

Remind me to answer the rest later cuz my typing finger is getting a cramp.:wink2:

Jaz
 
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#3 ·
Metalman what are the dimensions for that shower? What is below it, and do you have room to make it a little larger, so it does not feel like you are standing in a linen closet?

If you can stand in the middle and touch the walls without bending your arms, you may want to expand it.
 
#4 ·
Sorry guys, it's not possible to expand it. Besides, I'm moving in 2 years or less and so I just want to make it look nice before selling it. Dimensions are 32"x32".

I think it would be much easier to keep what I have then to rip all that down and start over. You really think it would be easier to tear all that down, deal with trying to dispose of that cement (a real pain), taking it down to the studs and doing all that work when all I need to do is just spend 20 minutes patching a few spots? That's If I can remove the pan without further damaging the mud base, but still, seems much easier to do what I am suggesting. I suppose the question is not "which is easier", but rather, if I patch the holes then thinset and lay my tile over the existing base, will I be prone to any problems, such as cracking tile or leaks. I've read this can be done on the johnbridge forums but in that case, the person didn't have to patch a few holes in the mud as I would have to. Otherwise the suggestion was to go for it. Same setup, mesh wire behind mud.
 
#5 ·
32"x32" is small. Even with you moving in a couple of years. Making it a little larger, will help with the sell.

Why can't you expand it a bit larger to say almost 4'x4'? Is this in an apartment, that another unit is on the other side?

You are going to have to rip down all of that mortar and Chicken Wire before you can do anything. It looks like brick behind the one wall.

The reason that they made the Plaster that thick, was for Fire control, to help keep the structure from burning down so fast. It is an art to get the new mix correct for repairing any areas that are loose or cracked.

You may be able to get by with Shluter to cover the old Plaster walls after repaired.

Jazman should be back on later tonight to cover anything that I missed or what will or will not work. Just hang tight for the day and check back around 7.
 
#13 ·
MetalMan said:
The house is in north Warren.
Oh yea, know it well. We moved to NE corner of Warren on Masonic Blvd. in a new house in '65 when I was still in high school.

What's the plan for tiling the floor? There's a 99.9% chance the floor is on mud too. Are you gonna rip that out or tile over the old tiles.

Feel free to check back when it's time to consider methods and products.

Jaz
 
#17 ·
I tore up the mudbed on the floor and there's a few of the wood slats that look pretty rough. How exactly do you replace these? None of the edges can be seen from above in the bathroom, meaning the ends extend into other rooms alongside the bathroom. Only thing I can thing of is to cut at the edges of the bathroom from above and replace the parts of the slats within the bathroom. I would nail in some 2x4 supports along the edges of the bathroom from below in between the joists to support the edges of the flooring. I'd probably ahve to replace the whole subfloor with plywood, huh? Not sure if this is a good plan or up to code, wasn't planning on having to do all this. It's never easy!
 

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#19 ·
Some are a bit warped. Some have some rot. Just wondering if I have to replace some or all of the subfloor.

How important is it that the wood slats (the bottom subfloor layer sitting on top of the joists) are completely flat and level? I'm thinking now that I should go with 3/4" ply over the subfloor with 1/4" cement board, that should equal my old floor height and meet the toilet flange flush. If the wood slats are a bit uneven though, can I get away with slapping the 3/4" ply over that to level it out?

And blocking is the term I was looking for... replacing the subfloor I'll need to add blocking around the edges of the new subfloor that I replaced in order to support the edges.
 
#21 · (Edited)
Yes there is a lot going on there. Tempering valve for toilet, exhaust for the power vent on the water heater, vent stack for the main DWV, bath drain.

That water stain is old. Just never cleaned it up, which is on the list, when we get mold removal in our attic from the old bath exhaust that finally got replaced.

 
#26 ·
Thanks Jaz. My planks are 3/4", just doubled checked. The 1x6 planks at Lowes were, I believe, 7/8". I have torn out the damaged planks only at this point. Just bought a toe kick saw and will cut to the edges and remove the rest today.

Do I need t&g? My space is so small that I won't be joining multiple sheets of plywood together, I can cover my entire area with one sheet. But I guess if the OSB all comes with t&g I have no choice. Since I will not be joining any t&g sections together, can I, or SHOULD I, cut off the tongue or groove edges? Or is it it fine to leave them as is when I lay the OSB down?

The toilet flange... do I reuse this I should I be replacing this? It would be a lot easier to work with the subfloor and laying it all down as one piece if the flange was removed. Then later I could just re-add a new flange to match the height of my new floor. If you think it's wise to go ahead and remove it now, how exactly do I do that?
 
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