Drywall around bath tub - over the lip, or against the lip?

I think the title is self explanatory - do I put it over the lip to sit against the bathtub, or do I put it against the lip? If it makes any difference I'm putting ceramic over all of this.

Thanks!
Nic

 

You would be better off putting cement board behind the tile since this is a wet location.

 

It's good that you stopped by to ask your question. You don't want to use sheetrock there. You want to use cement board. One product is called Durock and it comes in 3'x5'x1/2" sheets. It's available at most home improvement stores.

 

Cement board is a better option, but water resistant drywall can work, especially if this tub does not include a shower head. Whatever you use, it sits ON the lip, and the tiles go over the lip to the tub.

 

Keith, not very sound advice if this is a tub/shower. Better to verify first before broad stroking. Many people visit the forums and can take that as sound proof to move forward.

I have just mad a vow to myself that if doesn't matter where it is, be it on a bathroom wall, kitchen back splash, hearth surround, or simply a floor. If it is going to be tiled, cement backer will be used or another approved membrane such as ditra or kerdi. No short cuts, no easy arounds, just do it the way it should be done. There is a whole lot of piece of mind knowing that you installed it correctly, and there will be no issues down the road. I have built my reputation on it.

 

I don't mean to be combative, but it's crazy how literally every house I've seen use moisture resistant drywall, yet everyone on the internet and on television talk about that as though it was an absolute sacrilege.

I agree, cement board is the best bet, but it also very expensive, and I'm pretty sure moisture resistant drywall is made for that purpose and up to code, so what gives?

To add to that, the bathroom I am remodeling is 60 years old, and I just took down the walls around the tub to find nothing but clean, super dry, mold free drywall. If it can last 60 years...

 

Moisture resistant drywall will pass code for around a tub. It is a minimum requirement but there are much better products and methods avalible like mentioned above. I personny use cement board or a Keri membrane.

 

Years ago before the advent of cement board, a mud bed was the only choice, then came green board which sped up the tile job along with saving money BUT even though it was moisture resistant once a significant amount of moisture got behind the tile, the drywall and tile installed over it would fail! Today it's no big deal to use cement board which won't fail apart if it gets damp.

 

I also would only use cement board. But as others have said greenboard, and moisture resistant drywall is very common especially on homes build about 30 to 40 years ago. If installed properly it's not a big deal. Key words is installed properly.

 

Let's see.....4x8 sheet of 1/2" moisture resistant (not waterproof) sheet rock will run about $12.50 or 39 cents per square foot. A 3x5 sheet of durock will cost about $14 or 93 cents per square foot. You will be using a total of 66 square feet, so the difference in cost is about $36.

I do remodeling for a living, and have seen far more mushy walls in showers where sheetrock was used as a backer, than I have solid. I would absolutely NEVER chance a tile job to a $36 wall difference. Durock, Hardibacker, or a Schluter product (now we're talking expensive ) would be a better choice and will give peace of mind.

 

When I start using phases like "minimum code" it will be time for me to retire.

Drywall and "greenboard" are good for business. I have removed truckloads of the stuff. It only takes a small drip, wrong caulking, missing grout line, or error in installation of the finished wall to have a disaster. Greenboard does mold, it does degrade and it festers in the walls until things start falling off. Here is a recent thread, ask this person if he is enjoying his drywall in the shower - http://www.doityourself.com/forum/de...ub-shower.html. The last picture will be a omen.

This is a normal thing that I see everyday. Like I said, some of us make a pretty good living off of "minimum code" in the name of saving a buck.

 

OK, you guys are making good points, chandler, I agree that when you look at it from the perspective of a 36$ difference, it starts to make a lot of sense.

that being said, czizzi, let's be honest here, there is a difference between a properly tiled/grouted/caulked job and a tub that has been missing tiles for (presumably) years with a piece of shower curtain duct taped to the wall to protect the drywall (lol!)

 

Update: You guys win, I'm going to do cement board.

Can I tile directly over that, or do I need to seal it with redguard first?

Can I plaster over cement board (when the cement board meets the drywall beside my tub)?

It's frustrating how when I want to do a project EVERYTHING seems to be a can of worms. Obviously I'm just starting out and plan to remain in this field for the long run, so the learning curve is steep, especially because I don't want to cut corners, but damn.

 

It's not just missing tiles! Grout can and will crack, caulking will fail - theoretically if you stayed on top of everything, it would be ok but it's better to play it safe and not have to worry as much.

Normally plastic is put behind the cement board, when there isn't a moisture barrier behind the cement board you need to apply the redgard over the cement board. one or the other, not both.

 

are you talking about the same kind of plastic that is used for vapor barrier in a basement, or an actualy kerdi membrane?

 

The same or similar as used for a vapor barrier. They recommend a certain mil thickness but I don't remember what it is

 

6 mil poly or 15# felt paper that is layered down the wall. Set the first piece so that the felt overlaps into the tub (you will cut it back later). Overlap in the corners to the next stud in both directions. Overlap the next higher row so that it is shingled over the first row by at least 3". If taking tile all the way to the ceiling, then overlap a third row. Use a staple gun to keep it in place until you hang your 1/2" cement backer board. The theory is that any water that gets past the first line of defense will hit the felt paper and has no where else to go but back toward the tub. Use your cement backer mesh tape to mortar and tape the seams and corners of the cement board (same as the floor from your other thread). I like to run redgard across the seams and in the corners as an extra layer.

Plan on your cement backer board ending 1/2" before your tile will end so that the bullnose tile will cover the seam between the backer and the drywall. You may use regular mesh tape and regular drywall mud at that transition (I use easy sand 20 min. mud from a powder). Both the backerboard and the drywall at the transition need to be supported and nailed to a dedicated stud, nothing floats.

Don't forget that the inside corners and where the tub meets the tile get sealed with color matching caulk that is sold next to your grout and comes in all the same colors.

 

This was an approved method in the past and it may still fly in Canada, but not in the US if the area is using IRC 2006 or 2009. In case anyone is interesting in knowing exactly why moisture resistant drywall is not just a bad idea... it's not permitted, and why cement backer board is required... check IRC R702.3.8.1 and R702.4.2

Additionally, here is a link to some research done by one of our members, Doug Aleshire. http://dougaphs.smugmug.com/gallery/...7v5Gd&lb=1&s=L

In IRC 2003, moisture resistant drywall was allowed to be used in these areas provided it was not installed over the top of a vapor barrier. (so that it could dry into the wall if needed) This exception has been removed from IRC 2006 on.

 

You are right, the NBC of Canada does now require cement board behind tub/shower tiles as of 2010. I wasn't aware of the change since I always used cement board anyway.

Regarding R702.3.8.1 though, I am pretty sure that would be for something like suanas, not bathrooms.

 

XSleeper - thanks for the info. No worries though, I am going with durock.

Czizzi, I am on board with everything, except it is impossible for me to hide the seam behind my tile because of how the stack runs in the wall. Like you said, I don't want anything to float, so I am going to have to bring my cement board to the next stud over. Since I asked my question earlier today, I read, like you said, that I can use cement board mesh tape and regular joint compound to make a joint between the cement board and the drywall, just like I would do with normal drywall. Is this correct?

I have attached a picture so you can see. The person who had done this last time had nailed the drywall to the 3" pipe. Needless to say I'm not going to be doing that.

 

I see a patch, what is behind the wall on the other side of the pipe? My fear is it is another bath vanity. Can you access it to be able to do some tricky framing? And, if you lay a straight edge across the studs, how much room is there between the straight edge and the pipe?

 

Behind the wall is my kitchen.
There is literally no room between that pipe and the edge of the stud. It's pretty much flush with the drywall.

 

Codes are always dependent on the interpretation of the one enforcing them. However since R702.3.8.1 specifically says, "shall not be used where there will be direct exposure to water", I would interpret that to be the walls of a shower... which is why it's not allowed there... er, I mean here. "There" meaning on the walls in the shower. LOL

A ceiling in a shower doesn't get direct exposure... and it isn't subjected to "constant high humidity". So in other areas of a bathroom, (that will not get tile) moisture resistant gypsum would be a good choice.

Now that I've said all that, I don't know why I'm wasting my breath talking about US code to our OP when they are in Canada... guess I thought it was pertinent for our US readers. But I'm glad you got the chance to check the Canadian code, Keith.

 

Your not gonna like my solution that much, but it will (with some work) solve you problem.

You are going to have to school yourself a little on waste pipe installation. Cut the pipe coming from both the kitchen, and the vent from the tub. Install a 2x6 stud at the corner of the tub and then re-assemble the drain and vent going through the stud. You can notch a channel the fit the electrical wire into. Tricky part is going to be attaching the new stud to the base plate. If close enough to the edge of the tub, you should be able to get a couple of toe nails into it.



It is not as intimidating as it seems. Hopefully you can get some ABS piping locally and some ABS glue. A hacksaw is the only other tool you really need.

 

Not a big deal and very doable, but I'm still curious about my original question: Can you plaster the seem between drywall and cement board, just like you would finish normal drywall?

Thanks!

love the drawing by the way, looks sweet!

 

Yes, but use a setting type drywall compound like Easy Sand 20 minute. It dries harder and will hold better to a mesh tape. For the best finished look, try to plan your tile to overlap and cover this seam. Then you don't have to worry about it cracking out.

Place some kind of wooden support behind your diverter rough in valve and screw that thing off. The pex pipes have no strength to keep things from wiggling during use. I know you have the tub spout wrapped with something, but that won't keep it from twisting.

 

Goodness Gracious, I just picked up my durock from the store, and that crackling sound is really freaking me out. Just a little flex and it sounds like the board is going to snap right in half.

How careful do I need to be when I'm handling this stuff?

 

Once installed, the combination of thinset mortar and rigid tile adhered to it will stiffen it up solid as a rock. What you are hearing is the thin layer that is on top of the mesh fabric flexing (psst. Cement doesn't like to flex). However the core is solid. If it is compromised, you will know it. Play with a piece of scrap and you will understand. Thankfully, it is a base substrate and not a finished surface.

Also a good reason why we advise everyone that cement backer boards are not a structural item in applications like floors. A good base of plywood and/or OSB provide the stiffness. The cement backer provides the surface between them for a good bond.

 

you da man czizzi!
now I'll be all up to this forum's standards with my 6 mil plastic, backer board, and mesh tape and thinset in the joints.

 

Guess who is a dumbass?
I'll give you a hint: it's me.

I got creative with my backing solution for where the pipe is and I managed to squeeze a piece of plywood back there. I thought of posting it here to make sure it is a good idea, but I thought ''Enh, what could go wrong?'' and proceeded to install my backerboard.

I was at it until 11 last night, taped and sealed and everything. Very proud of myself. Then I decided to wash my hands in the sink from the bathroom.

Guess what happened?

click.......click........CLICK CLICK CLICK CLICK CLICK because the waste pipe didn't have room to work.

So this morning I took a section of the backerboard apart and now I'm exploring other solutions but I think I figured it out.

I'm actually really happy this happened because it helped me notice that the waste pipe was actually leaking where there is a cuplink, so I'm gonna get to patch that up.

I also noticed that the tile I had that doesnt work with my bath. I shaked it off and went on to replace my ''Razor only'' outlet to a GFCI one, and have been going crazy trying to figure that weirdness out for 2 hours (I posted this in the electrical forum).

meanwhile my friends sent me a picture of them catching a monster pike through the ice at the spot I took them 6 times so far this winter without catching a thing. I kept convincing them that I trust the spot. so today they said they would give me one last chance. I had to cancel last minute, they went anyways, and they caught the monster I've been looking for.

I'm sorry, this is more of a rant than anything else, but I can't wait to catch a break. Not a good saturday.