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OurHouse 06-17-2012 10:52 AM

Tiling tub/shower surround w/plaster & lath walls
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It has been almost a year since we bought our house :eek:

We have guests coming to stay with us soon and the main bathroom (a.k.a. "nightmare bath") is getting a facelift. We ran fresh Pex plumbing lines yesterday to bypass all the galv the idiot plumber left in the last time the walls/ceiling were open, and the next thing on the list is to make the tub/shower useful again. The house was built in 1913, and the tub surround has plaster and lath walls that had had faux tile paneling on them, and amazingly there are no signs anywhere of water permeating underneath or water damage. (The previous owners did, however, have shower curtains hung on all 4 sides of the tub, which we won't be repeating.) There is a window in the back wall of the tub surround, so we will be hanging a curtain rod to have a shower curtain protect it because it's the only light source, and it's just not something we want to remove from the perspective of outside aesthetics, either.

We looked at that water proof paneling yesterday for a "quick fix" so the guests won't need the master bath for showering, but at $23/sheet and needing 4 sheets, my husband said I should tile it, instead. (Lucky for him he's not the handyman of the house, so it's very easy to say what "should" be done :laughing:) But I digress...

We found simple subway tile to be pretty affordable, and we're putting the mold resistant green board on one end because we need to close it in, but around the window and at the other end of the tub, do we just slap up 1/2" green board, right on top of the plaster and lath walls? (If there were 1/4" greenboard, I'd be much happier, because I want to maintain some space around the tub sides to set shampoo and stuff, and with the 1/2" plus the tile/grout/etc, we're eating up precious space.

Also, this is my first time working with greenboard, but it would seem one wouldn't use basic mud and tape at the joints of greenboard because the whole point is moisture/mold resistance, so what do I "mud" this stuff together with so I can get tiling? (And are there special screws I need, or can I just use my course thread drywall screws?) And following the "mud" drying, is there any pro tips for prep to tile? Anything I should be doing to get maximum adhesion of tile and awesome grout lines and grout protection? (I'm taking tips early here because last time I tiled I got suckered by the store into this grout additive that was a :censored:nightmare to work with.)

Thanks, in advance, for you're awesome advice :wink:

joecaption 06-17-2012 11:00 AM

No green board can be used in a wet area.
To do it right all that old plaster has to go, use tile board instead.
The wall will have to be shimed to make up for the thickness of the old plaster.

The tile board will need to be water proofed with a product like Red Guard before the tile goes up.
I've never seen or heard of 1/4 green board.

Only place green board should be used is above the enclosure and the rest of the bathroom, not in the shower area when it gets wet at all.

Not a great idea to have a window in the shower area unless you plan on installing a vinyl window with vinyl trim and sealing the whole thing.
A Solor Tube would give you all the natural light you need if there's a roof above the room.

OurHouse 06-17-2012 11:40 AM

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Tile board? Hmmm this is something I have definately never heard of. Thanks for that tip. Is tile board the same as cement board or "hardie backer?" Oy removing all the plaster and lath is gonna SUCK....

The window, I know it's not a "good idea" but it's a 100 year old house. Many of the old ideas weren't exactly brilliant for todays living, but she's <my house> got her own kinda charm. This shower isn't the master shower that gets the most use, and with our curtain rod going over the window and providing a shower curtain that can suction at the sides to the wall, I think we can keep that window OK. Is it ideal? No. But it is what it is. She's an old house, and I didn't buy her to take her character and charm away and make it new.

How horrible would it be to add the tile board over the plaster and lath? :whistling2: I've had to remove plaster and lath in other places and man oh man is that a :censored: because you often end up removing more than you want to remove because it keeps cracking wider and wider :(

joecaption 06-17-2012 01:04 PM

If you precut it with a 4-1/2" grinder with a masonry blade or a diamond blade you can stop it anyplace you want to.

Evstarr 06-17-2012 02:22 PM

Why can't she install a waterproof membrane over the plaster and tile over that ?

oh'mike 06-17-2012 06:35 PM


Originally Posted by Evstarr (Post 945523)
Why can't she install a waterproof membrane over the plaster and tile over that ?

The tile board that Joe is referring is a product like Durrock or hardibacker--

Cement board--1/2"

Evstarr is talking about a waterproof surface membrane--

Schluter makes the best known of these types--Kerdi is the brand name--

Lots of good Youtube videos available--go to the Schluter site for the real low down.

---Mike---(Jazman is highly experienced with all the above methods--If he offers any advice,it will be good----)

Fix'n it 06-17-2012 08:58 PM

i did kerdi in my last shower. good stuff. back then, 4 years ago, they said to use regular dry wall. i used green board.

OurHouse 06-18-2012 12:36 AM

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Thanks for the ideas. I have to see this Kerdi stuff. I hate hate hate removing the plaster and lath because it can be brittle and hard to control and there's often really sharp metal mesh in there, too, and it turns up somewhat randomly and, well, I like my surgeries planned :laughing: and I don't want any stitches. (Running the pex lines we pulled some and yeeesh it is hardcore. Were the old timers building these places leather-skinned?

Bonzai 06-18-2012 01:24 AM

This may depend where you are located but green board (some times referred to as aqua board and not always green ... I've seen purple too) can be used in a shower by minimum code, but I would not recommend it. This is what was used in our 5 year old home as I recently discovered. There is also 'Wonderboard' which I personally detest as it is a pain in the ass to work with, crumbles easily and is full of thousands of holes so if using a product like Red Guard for waterproofing it takes a lot of coats. I find it a very ironic name as it is anything but wonderful ;-)
We tend to use either 1/2" cement board or Dens-shield which you can work with using drywall tools and is much lighter. I would look for the 8' sheets though as the 4'x3' sheets mean more joins which means more areas to potentially leak. You can also use regular drywall screws with Dens-shield as opposed to the super pricey ones needed for cement board ... Although decking screws can work in their place. Cement board is also hazardous when working with it so be sure to wear a filter face mask.

Make sure to use the mildew resistant mesh tape for the corners and joins ... Not regular drywall mesh tape. Use a thin mix of thinset as the 'mud' to embed the tape and fill the joins/corners. Once dry sand this so there are no abrupt ridges and the corners are square. Rounded corners or ridges will be a pain when it comes to tiling. For the corners I use the back of my knife to imbed the tape in the corner slightly so it is a bit of an acute angle like a proper drywall corner. I used to use Kerdi for the whole shower but my system I have developed now is to use Kerdi for the bottom 16" (one piece going around all 3 walls assuming an alcove shower) and then the Mapei equivalent of Red guard (same idea but blue) for everything above that. 2 coats of the Mapei product rolled on with a 6" roller is enough to cover any small holes in the mesh tape/mud and equivalent to the thickness of the Kerdi so you end up with a uniform surface for tile. Bear in mind the Dens-shield has a built in vapor barrier on both sides so really I am adding extra layers but I like to have a bullet proof system.

FYI: if installing Dens-shield on an external wall you are supposed to remove the existing vapor barrier from that part of the wall so as not to cause condensation between the 2 vapor barriers. I've heard people from different climates talk about having/not having vapor barrier on the inside of the studs but I'm just saying what the manufacturer recommend if you do ;-)

Note: pay close attention with Kerdi as to when to use polymer modified thinset versus non-modified thinset.

OurHouse 06-18-2012 01:32 AM

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Thanks Bonzai, for a really informative response. I highly doubt there is a vapor barrier in the external wall as the house is so old. I'm really digging the idea of a rolled on product to seal that tub/shower. It would mean a lot less difficult fussing around the window, too. I had no idea cement board was hazardous. More than a 95 mask required for simply keeping dust out of the lungs during cuts?

Bonzai 06-18-2012 09:16 AM

95 mask is fine. You may want to cut it outside though as makes for a whole lot of dust. Bear in mind you need a good hole saw to make the cuts for the shower head and faucet if using cement board. Also ensure that the window ledge slopes back towards the shower slightly ... Just enough for water to run off.

OurHouse 06-18-2012 09:55 PM

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Originally Posted by Bonzai (Post 946050)
95 mask is fine. You may want to cut it outside though as makes for a whole lot of dust. Bear in mind you need a good hole saw to make the cuts for the shower head and faucet if using cement board. Also ensure that the window ledge slopes back towards the shower slightly ... Just enough for water to run off.

I killed two hole saws on cementboard with the previous bathroom floor :laughing: I'm really flirting with the idea of using the kerdi all the way up, against greenboard (I bought the greenboard before and it's already cut.) If I just run Kerdi around the bottom and then another row above it (overlapping a bit to keep water out) and another above it, etc, that's going to be pretty darned rubberized... I have 2 more days before I can resume my project, so I have some thought time. Kerdi all the way up or the roll on 3-4 layers, which is better, that is the question now...

And no one ever did answer if I absolutely truly shouldn't Kerdi or paint seal the plaster and lath walls, so I gotta be honest, I'm leaning against opening the areas I don't have to open... I mean, it has survived in that envirnment with faux tile board over it that wasn't meant for a tub environment and there has been ZERO damage to it, so, :whistling2: (plus if I were to have issues with removing it, the other side of the wall is the living room staircase which I'm really really really not ready to touch yet) I know I'll get some eye rolls for this, but sometimes there's the right right way that is 100% by the book of best practices and then there's something pretty close that will work out fine. I'm not talking out and out Mickey Mousing, just choosing my battles and not subjecting myself to more drama that absolutely required, because this bathroom and shower must be functional by July 5th. So I'm really interested as to whether anyone has seen a well sealed plaster and lath situation like mine with say Kerdi or the painted sealant or both? (Or anyone wanna give me the nightmare scenario that I'm thinking is unlikely?) :detective:

Bonzai 06-18-2012 10:45 PM

JoeCaption already advised that the lath and plaster should go if you're going to do it right.

OurHouse 06-19-2012 05:02 PM

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Maybe I misread, but Evstarr asked why I couldn't, and oh'mike weighed in seeming to leave the question on the table, and Fix'n It seemed to leave it on the table, too. I don't have a grinder, thus my only weapon of choice left for the plaster and lath would be the Sawzall or circular saw, so I'm really not looking forward to doing the rip out unless I have absolutely must must must. Guess I better go call some friends regarding borrowing a grinder, but I'm not hopeful...

Fix'n it 06-19-2012 09:12 PM

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if the P&L is a tough as you say. and is finished so it will hold onto the mud that you will be using to apply the kerdi, you can leave it up . how long will it last ? who knows.

other than that, with kerdi = FOLLOW THE DIRECTIONS ! and it still has a learning curve. at first, i didn't find it easy to install.

pics i dug up. i have better pics somewhere, but can't find them :wink:

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