Hello NG,
I'm tiling a very small quarter bath (shower) in the wet part of Oregon. In other places, I've thought that the expense of Durock wasn't worth it, but I'm leaning toward recommending it for this job.
Floor is concrete, bottom floor of 2 stories.
What say you?
| I'm tiling a very small quarter bath (shower) in the wet part of Oregon. | In other places, I've thought that the expense of Durock wasn't worth | it, but I'm leaning toward recommending it for this job. |
I wouldn't tile on drywall even in a dry room. It's just stuck to paper. In the 80s, before concrete board and after metal lath was common, most tiling was either on plywood or drywall. The former would pop off due to expansion/contraction, while the latter had a short life expectancy - often less than 10 years, depending on how carefully one caulked to keep water out of the wall.
I only tile on concrete board with thinset. It's more work than using tile mastic and/or drywall, but the result is a mortar wall that will last.
Side note: I've noticed that greenboard is no longer grayish inside, and sometimes comes as "purpleboard". I'm curious whether anyone knows the story there. I thought greenboard probably had tar to make it water-resistant, and that maybe that was banned, but I don't know.
IMHO the only choice you have available is between durock or hardibacker.
Jon
I used Hardibacker for our showers. It's thinner and easier to cut.
The backerboard is a minimal cost compared to the rest of a tiling project.
Do it once, do it right.
Anthony Watson
I doubt the code would even allow green or purple board in a shower and certainly not below 4 or 5 feet.
Do it once, do it right. Use Kerdi (Shluter system) Either standard Kerdi over whatever wallboard you want to use, or KerdiBoard. You don't need soncrete backer with Kerdi, and you use thinset - it is totally waterproof and pretty well goofproof. It is not particularly cheap, but good seldom is. It has a handy "grid" for helping to keep the tile-job square. They also have KerdiDrain for the bottom of the shower (pan) to use with Ditra to make a waterproof shower pan.
Alright, it's between durock, hardibacker, and plywood.
Would plywood have to be treated?
How thick on the durock?
How thick on the hardibacker?
Small shower....
| Alright, it's between durock, hardibacker, and plywood. |
No, it's not. Read my post. It's between hardibacker and concrete board.
Or any of the above with the shluter system
Cal is 100% right to look at Kerdi. Mapei makes a similar product, but the Kerdi has it all.- at least make yourself aware of the product:
Schluter has been in the tile industry a long time.
Thx for your comment, Maya, I didn't read closely enough. Do you plywood behind joints (between studs) as backer?
Can we use ordinary drywall mesh for the seam?
Agreed! We used the standard Kerdi for our showers:
I had not heard of Kerdiboard. It looks interesting but wasn't available when we built out house in 2003.
Anthony Watson
Hardibacker comes in 3'x5' sheets (Durock can be bought in 4'x8' sheets). In most showers a single sheet will span wall to wall so you shouldn't have any seams. However, if you need to have a joint cut the sheets as needed so the seam ends up over a stud.
Adding blocking behind horizontal seams would add a little extra strength, but it is not a necessity if you tape and mortar the joints (similar to taping drywall joints).
I used the mesh specifically sold for taping backerboard seams, but I don't think there's any real difference from the regular fiberglass tape used with drywall. Still, a roll is only $4 so it seems pointless to guess on something so inexpensive.
Anthony Watson
I have the Kerdi drain in anticipation of finishing my shower.
Greg
| Thx for your comment, Maya, I didn't read closely enough. Do you plywood | behind joints (between studs) as backer? |
I usually just try to leave such joints high up. As Anthony said, it come 1/2"x3'x5'. (I've never seen 4x8 where I am.) So it's basically one sheet on each end and two in the middle. The joint where they meet should be a stud.
Staple plastic on the studs first and cut it at the bottom after boarding. If you then caulk that joint before tiling you'll have 2 caulk joints at the end to keep water out of the wall. (The concrete board companies at least used to recommend no plastic, in order to let it air out behind if it gets wet. That doesn't make sense to me. First, it shouldn't get wet. Second, if it ever does the concrete board can tolerate being damp for far longer than the studs can.)
I had one job where the customer apparently fell against the wall and a crack in the tile resulted. I assumed it must have been on a joint and offered to replace that tile. It turned out not to be on a joint. It was in the middle of the board. As far as I could tell, the cause seemed to be a combination of flex in the concrete board and cheap tile that was soft. I don't actually know, though, what they did to cause the cracks. But the moral of that story for me is to avoid large spans. Some horizontal blocking is not a bad idea if that's practical.
Personally I don't trust hardibacker, but I've never actually used it. I'm just wary of a composite product. Like using chipboard for house sheathing. It's legal. It seems to work. But what if the glue breaks down in 20 years?
30 years? 40 years? Or even 10 years. There's a lot of technology out there that hasn't been around long enough to be time-tested.| Can we use ordinary drywall mesh for the seam? | I'd double it if you do that. The concrete board mesh tape is stronger, though.
| If you use the plastic, it will trap the small amount of moisture that WILL go | through the grout, resulting in possible mildew problems. Better to use a few | coats of Redgard or a similar product on the concrete board before tiling. | Without any coating, moisture can evaporate after going through the backerboard | so that moisture does not build up to cause problems. |
That's the theory, but it doesn't make sense to me. Moisture can migrate through the top if it gets through. But if there's a break, and lack of plastic is letting moisture reach a stud, then eventually the whole thing will have to be redone. I've always used plastic and never had a problem.
I just looked up Redgard. Personally I'd be very dubious about such a product. You'll end up not with a mortar wall but with tile stuck to a plastic coating, that's in turn stuck to the concrete board. Will that hold up? Who knows? Another product that's not necessary and not time-tested.
Also, if you waterproof the concrete board you haven't done anything to stop water getting through. Leaks won't happen in the middle of the sheet. They'll happen at the bottom, corners, or around fixtures. In those areas a coating on the concrete board won't help.
The idea is that you only want one moisture barrier, and with so many houses now using housewrap, if you put plastic on the studs you are creating an area in which any trapped moisture has no where to go. As the dewpoint changes, this trapped moisture will, at times, condense, leading to mold problems.
In my shower I just put the hardibacker right on the studs, then slathered it with redgard before I began tiling (using thinset mortar, of course).
Jon
| The idea is that you only want one moisture barrier, and with so many | houses now using housewrap, if you put plastic on the studs you are | creating an area in which any trapped moisture has no where to go. As | the dewpoint changes, this trapped moisture will, at times, condense, | leading to mold problems. |
That's not actually how it works. The housewrap should be a wind barrier that allows moisture to migrate through.
"The TYPAR Weather Protection System. It provides exceptional air and water holdout, optimal moisture vapor transmission"
(I wouldn't trust housewrap to stop liquid water, but that's another debate. :)
The inside walls can then be covered in plastic as a moisture barrier. So moisture is never getting into the walls from the inside in the first place. That's also a nice bonus where winters result in very dry indoor air.
Though in most of the places I work houses are not wrapped. They may have tar paper, but the walls are usually leaky in terms of air flow. Old houses are not wrapped unless they're wood and have been completely redone on the outside, with all the old siding stripped off. Where I live that's not at all common. In fact, I'm often dealing with houses that have incomplete or no insulation.
| In my shower I just put the hardibacker right on the studs, then | slathered it with redgard before I began tiling (using thinset mortar, | of course). |
I'd consider that an unnecessary experiment. Hopefully it works out OK. But your thinset is now not bonded to the hardibacker. It's bonded to the Redgard plastic coating. You've lost the advantage of producing a composite mortar wall. With concrete board, thinset and tile you'd end up with essentially a single mortar panel.
We've discussed this issue before. People have different opinions. To my mind there are an awfully lot of new inventions that are not time-tested and for which there's really no standards system to decide whether they actually make sense. I'd consider hardibacker, Redgard and waffle sheet underlayment all to be in that category -- claiming to solve a non-existent problem. Though I would be interested if someone came up with an easier- to-use version of concrete board that's also stronger. It's too easy to cause cracks in the concrete filler by bending and hitting.
Just use the shluter system and be done with it. 100% water and moisture proof. No second guessing.
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