My new home under construction has a large walk-in shower which is tiled (ceramic) top to bottom including the wet area (shower) and the area out side the shower. The wall is prepped using expanded metal mesh with a cement mastic material (looks like smooth stucco) instead of cement board over sheet rock.
My question is: Is it absolutely necessary to use green board sheetrock in those areas that won’t get wet? The board is installed in the wet areas only. Do I need to urge the builder install green sheetrock in all areas which will have tile wet or dry?
Replies
Yes. Where ever moisture is of concern, be safe and go with the MR drywall. The extra cost is minimal and may save much $ in the future.
J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
J-man,
I put 5/8's MR in my bath ceilings and later thought that someone on this forum said ceilings were a no-no for green board.
Got an opinion? If not then what does one use?
I can`t count how many ceilings I`ve used MR on, I`ve never had a problem with any. If it is a major concern of yours, shrink the spanning down to 12" OC. I never have but, you might be better off. At least you`ll meet manufacturers standards.J. D. Reynolds
Home Improvements
"DO IT RIGHT, DO IT ONCE"
For baths, here is what I like for cement board vs gypsum board:
Wherever there will be tile, it's backed with cement board.
Wherever there will be painted drywall, it's green.
Ceilings? The manufacturers have disclaimers and caveats regarding the use of greenboard on ceilings. The additives in the core that make it MR also make it less stiff, thus more susceptible to sag. So, while they say don't use it on ceilings, they also say use it on ceilings but with the framing not greater than 12" oc. Leave the framing as is...16" oc is common...then strap or furr it to 12" oc.
I went round and round years ago and finally got a fax from USG recommending MR over 12" oc framing for ceilings as an approved method. The fax is filed away.
Yes, there are other ways....this is simply my way. Never a problem.
IMHO, as one who use to do maintenance at several apartment complexes -Have been an electrician for quite some time since then- , I saw quite a bit of damaged drywall. The green board seemed to be take less of a hit but it too was subject to damage. The one solution that consistently worked was backer board. I never saw concrete backer board, the only sort available back then, fail due to water damage. The framing went south before the board gave in.
Green board seems to be a poor substitute for backer board. If it's dry go with regular drywall. Wet, or subject to getting wet, go with backer. You are only going to build your dream house once. Go all the way. Don't try to split the difference.
I seldom regret buying top of the line tools. I often regret trying to save just a little on the price with cheaper ones that don't last or work as well. Build walls you can count on.
green board......for ceilings..........latest I've heard/read is...
1/2 at 12 o.c.....or 5/8th at 16 o.c.
and don't substitute green board for cement board behind tile.
Green board is drywall.........and should be used as such.
cement board is tile backer......and should be used as such.
JeffBuck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
Okay, so what I'm hearing is, that as long as you have cement board, you don't have to have the green board behind it?
You do not put green board behind cement board. Glue and screw will make it plenty strong.
If you want to do a professional job that will outlast the rest of the house do your wet areas in lathe/portland cement and the balance in rocklathe/plaster. Green board is ok for ceilings. There is no prevention for corner movement when using cement board so expect leaks. Unless you caulk all corners which is not appealing.
Curiosity... Won't an acrylic base coat with mesh, or acrylic modified thinset with mesh help with this?
I take it you are responding to my comment regarding movement with corners formed with cement backer? No- you are attempting to stabilize the movement with materials that:
1) Have little strength in opposing structural forces.
2) Are water resistant not waterproof, and I might add that once permeated by moisture/water failure is inevitable.
That's why most contractors are remodeling baths with a life of 5 yrs, at best 10 yrs.
what part of the country are you in? My average tile tear out was last remodeled 30, 40 or 50 yrs ago!
The cab's and vanities are usually newer.....but the tile's usually older than I am.
JeffBuck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
I was surprised by the 5 years, too.
So what exactly is under all that tile that has lasted 30, 40, 50 yrs? What I am saying is the green board and cement board remodels typically do not last more than 10 yrs and require a lot of maintenance and repair.
Does it help to use a silicone sealer on your grout joints?
The first tile job I did was as a teenager in my parents house in 1972. Mastic out of a can on greenboard. It's still there.
The last tile job I did was two years ago. Wirelath, wet mortar bed, topped with waterproof membrane and black goop (forget the name of the product) then tile. I expect that one will last at least as long as my first one.
I think that once you are outside of the areas of direct water contact (shower surround, countertops) it's all overkill. If it's getting wet where there isn't direct water exposure, you've got bigger problems than whether the drywall is green or not.
Steve
what's behind them is usually the rocklath or real lath that you mention.....but they don't last that long because of the backing materials...the last that long because of the facing materials.
Install the tile right..and it's not gonna leak in 5 to 10 yrs. It's gonna last just as long as those jobs I mentioned.
At the subsurface level...cement board...with mesh taped/thinsetted seams.....is no less "waterproof" than horse hair plaster.
And a badly maintained or installed tile job over plaster and lath is gonna last no longer than one over drywall.
Learn to install the system right...use cement board....tape the seams.....tile away.....grout the flats and grout caulk the corners...and against differing materials....and the tile job will still be there when you are ready to sell.
JeffBuck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
If it's wet cement board. Shower walls, tub surrounds, any ceamic tile floor. There is no substitue for doing it right, no gyp product will hold up as well.