Hey all,

I recently bought an old home and am SLOWLY renovating it. I just got to the bathroom and have removed the old tiles from the plaster walls.

I'm wondering if I can hang 1/4" durock directly on the plaster and whats left of the mastic (driling into the studs), then tile right over that? Should I hang vapor barrier between the plaster and durock? I'm really trying to avoid taking down all that plaster and everything behind it.

Thanks in advance

 

So, you're just remodling and not renovating the bathroom ?

You could , but no plastic.

Personally I'd be tearing open the walls and correcting problems that are more than likely there. Also would provide an opportunity to beef up the insulation.

 

Honestly, for the small effort, remove the plaster and give yourself a pristine stud wall with which to begin your rebuild. Why complicate it with what seems like a shortcut, but in the long run will be a burden to the process.

 

Well, I'm worried that I just don't have the skill set needed for a full gut job if for some reason I encounter something 'off' under there. It sounds easier to just throw cement board up on the already leveled plaster walls. Also, I'm afraid that tearing down plaster walls will force me to take down the curved plaster ceiling.

 

You want to cut out the perimeter of the plaster to be removed first. That should prevent any damage to the surrounding plaster [other than maybe an inch or so] We can walk you thru all the stages of the job.

btw - welcome to the forums!

 

1/4" Cement board is not really meant for walls, however can be used in certain circumstances. What I do, is define the are to receive tile, calculate how high up the wall the tile will go (including bullnose) and measure 1/2" short of that mark. I then remove the wall below that line down to the studs. I measure the thickness of the plaster (it will vary) and cut shims thick enough so that the shim + 1/2" cement board = original thickness of the wall. I then tile up to and overlap by the 1/2" and finish the job leaving the wall intact above the tile. Caulk the transition and you are complete. You need not and should not, have to remove the whole wall such that you would jeopardize the ceiling install in any way.

 

Thanks for the responses...

I've decided to do it right and take the walls down (with your help)... I've done plenty of non bathroom work/walls and tiling, but this will be my first experience with concrete board....

So, I'll take the walls off within an inch or so of the ceiling (tiling entire wall), then put up 1/2" concrete board. Make sure its flush using shims, etc. Do I treat it as I would drywall (tape, plaster), or is there a different way of working with it? Whats the consensus on a vapor barrier? Anything I'm missing?

Thanks in advance

 

You need a vapor barrier behind the cement board. I'm a painter not a tile guy but most use a mesh tape embedded in thinset as they set the tile

 

The box stores sell a heavy guage mesh tape specific for taping seams between cement boards. In the big orange store it is located in the section where you would purchase drywall supplies, its is gray in color and labeled for cement board. You use a very thin layer of thinset to set the mesh. Mesh is used between boards and also in the corners where boards meet. Do not overdue the thinset on the tape or a bump will cause you headaches when tile is applied. Remember, cement dries hard, unlike drywall mud which can be sanded, you basically get one shot with the thinset.

I use 15# roofing felt for a vapor barrier stapled directly to the studs. Start at the bottom part of the wall, overlap into the tub or base and also overlap the next piece so that any liquid that would make its way to the felt paper eventually will be directed back into the tub/base. Overlap around 3 inches for each layer and make sure you are a hard 90 degrees in the corners or the cement board will tear it when you try to put that up.

 

That depends --- are you planning to use a water proofing membrane like the Schuter Ditra ?

Btw -- 15# roofing felt is not a vapour barrier. It would be considered a moisture barrier which is different.

 

Wow, thanks for all the info... I'm really looking forward to this project!

Cost aside, which would be better? Using something like 6 mil plastic behind the cement board, or putting the cement board directly on the studs and covering with a schluter membrane? If I used a membrane, do I still have to tape the pieces of cement board together, or will it also serve that function?

 

Let's put it this way ---
with just putting the backer board without a waterproof membrane then you would need a vapour barrier like the 6mil poly.
Reason being --- the grout lines and the backer board are not vapour retarders and without the 6mil poly will allow vapour ( and there will be plenty ) to pass through and condense within the wall cavity.

Now the tricky part--- technically the vapour barrier should be continious from the bottom plate to top plate of the wall framing and well sealed. That wouldn't be the case in your situation since you are leaving a portion of the existing plaster up near the ceiling. You likely wouldn't be able to successfully get the 6mil poly up to the top plate and properly seal it.

A workaround to this --- you are going to need some sort of blocking in order to fasten the top of the backer board and the bottom of the remaining wall -- where they meet.
The portion of this blocking (for the top of the backer board ) is where the 6mil poly gets attached to and sealed. I would recommend using acoustical sealant which comes in a caulking tube -- it's a black material that doesn't cure and remains flexable -- it should also be used along the bottom of the wall.

With a waterproofing membrane , like the Ditra ( excellent product by the way ) this is also vapour barrier and it's on the warm side of the room. You do not want or need to have another vapour barrier behind the backer board which is now on the cold side.

On one hand you can say the using Ditra on the backer board would be best for a couple of reasons -- it waterproofs the wall ( even though you're using backer board it's not waterproof ) and provides a vapour barrier.


I would definately recommend it. I've seen where an installer didn't saying the Ditra would be the same thing . Where there were seams in the backer board that weren't taped had cracks in the grout and other problems with the tiles.
Bottom line --- it isn't that expensive to do it upfront and not worth cutting corners it's really expensive to fix things after.

2 cents worth.

 

I'm not a tile guy, but here is some info I have for when I will tile mine; Ceramic Tile Intstitute of America - Field Report #46

http://www.google.com/url?sa=t&rct=j...2Qi6yxaqVetTEg

http://www.google.com/url?sa=t&rct=j...nNWXFt5rx5cW2Q

Bathroom Remodeling the Smart Way-Phase 4 (Installing Cement Board on the Back Wall)

Gary

 

Thanks for the great resources/information!

I'm almost done with demo, and plan on starting everything right after Thanksgiving weekend.

So, here are the steps I have planned out. Please tell me where I'm wrong:

1) Build subfloor with 3/4" plywood, thin-set, and 1/2" cement board

2) Level out the studs, then attach cement board to the walls, starting about 1/4" above the tub and going up to the plaster perimeter at the ceiling.

3) Seal walls using Hydroguard membrane and fiberglass tape over the joints (or thinset and Kerdi over everything?)

4) Apply Ditra system over the floor.

Anything missing? What do I do where the subfloor meets the walls?

 

Oops --- I mistakenly said Ditra on the wall when it should have been Kerdi ( which is another great product ).

Which brings up another thing --- the Kerdi board.
You might consider this instead of the durarock.


If you don't need to buildup the height of the floor you really don't need the 1/2 cement board when using the Ditra.

 

Me again...

It has been an educational/painful few months to say the least...

Gutted the second floor bathroom to studs, installed pex from the basement up to the bathroom replacing the 100 year old pipes. Also installed a new drain into my stack taking my tub from left handed drain to a right handed drain (only way we could have a shower).

Updated the electrical. Installed insulation in the previously insulation-less walls (we're in Michigan).

FINALLY pulled up the floor (tile on two layers of vinyl on tongue and groove oak on pine slats) and am down to the joists. Went ahead and screwed down 3/4" plywood with plans to put in the new tub tomorrow and then cementboard the rest of the plywood so as to get a tiler in by next week (running low on time)

THE PROBLEM:
AFTER screwing down my 3/4" I decide to check my floor with a level. You guessed it - I'm off. I'm guessing the last joist is about 1/8-1/4" higher than the other joists, but all the joists seem to vary slightly. I'm attributing it to the house settling with time...

So, what to do? I REALLY don't want to pull up the plywood, but will if need be. Should I pull it up, shim the lower joists, make sure everything is level with a 4' level? Should I leave as is, shim the tub (using Bootzcast steel and foam) and proceed? Should I create a mini ice skating rink of leveling compound?

Really appreciate any words of helpful wisdom..

Thanks

 

Only you can see how bad the floor is. The tub is deep enough that 1/4" will not make much of a difference. People mostly take showers and the only time you will notice the out of level on the tub is when it is filled with water. The bigger issue is how it will play into the installation of the floor tile. If you are a stickler you can you can use a 3/8" x 1/4" trowel and float the difference when installing the tile. You will need to be gentle with the handling of any tile you float as any pressure will lose the orientation relative the to next tile and the floor will be "lippy" as we call it. Best way is to sister the joist to bring all to level, but you need to make that call.

 

I was hoping you wouldn't say I need to sister the joist. I'd have to sister at least half of them = huge headache. But, better do it right now than have a headache later

What about sistering the joists vs just using shims/rough cut pieces of wood to bring everything level?

 

If you can custom rip shims to go the full length of the joists, that is great. Use liquid nails rated for subfloors prior to nailing the shims in place.

If you went the SLC way, you would have to install wire lath and then float the whole floor over the top of that which is more challenging than it sounds.

 

Thanks for all the help.

Cutting custom shims turned out to be trickier than expected, so I ended up sistering the joists. It looks like the entire house has shifted over the past 100 years, with one side of the bathroom about 1.5 inches lower than the opposite end. Of course that is all corrected now. But, at the door my 3/4" plywood is now nearly level with the hardwood in the hallway. I originally had plans to put 1/2" cementboard down on the plywood but am afraid that it may be too high. Any chance I can get away with 1/4" cement board?

Thanks again

 

The thickness of the cement board doesn't matter. You could even use Ditra in place of cement board.