Tile Backing In Tub Surround

[BMWMK2]

Hello Everyone.

I Am Brand New To The Forum And I Have To Tell You It Is The Greatest Thing Since Sliced Bread.

Now For My Question, I Am Redoing My Old Bathroom Which Now Has A 54"tub With No Shower Riser Or Tile, I Tore Out The Portion Of Plaster And Lath To Install The Riser, Sweated The 1/2"fitting And The Elbow Fitting To The Top Of The Pipe And Installed, Braced The Fitting To A 2x4 And The Faucet, Ran The Shower Into A Bucket And Checked The Fittings , No Leaks, It Was My First Time Sweating Copper Pipe So I Am Thrilled. But Now I Have The Rest Of The Walls To Take Down, Should I Replace Them With Concrete Board Or The Green Board? Also How Do I Get Them To Be Flush With The Rest Of The Bathrooms Plaster And Lath Walls Which Are About 3/4" Thick?

Thanks Mike

[jadnashua]

Tear out the walls to the studs. No greenboard, use 1/2" cbu. If you aren't going to tile all the way to the ceiling, you can stop the cbu about 6" above the showerhead and put in drywall. Figure a place where that last row of tile can bridge the cbu to drywall so it is easier to make the paint look good. Depending on the tile (thickness) you use, you may want to shim the studs out to compensate for the plastered walls you have. Behind the cbu, put us either 6mil plastic sheeting or roofing felt to act as a vapor barrier. Run this down over the lip of the tub and cut it off after you get the cbu up. Leave an 1/8-1/4" gap between the top of the tub and the bottom edge of the cbu. Leave the tile up about 1/8" inch and caulk that joint after finished with the grout. If you have insulation in the walls and it has a vapor barrier, slash it to compromise it - two vapor barriers is not a good thing.

www.johnbridge.com is a great place to ask tiling questions. Here is a great place for HVAC and plumbing issues - we do pretty well on other things as well, but why not go to the tiling experts?

[BMWMK2]

OK CALL ME A MORON BUT WHAT IS CBU? AND THANKS FOR THE VAPOR BARRIER TIP I DIDNT KNOW THAT.

[jadnashua]

cement backer unit (cement backer board). Many people think cbu is waterproof - it is not, it will wick water. It is just not damaged by moisture. It expands and contracts at about the same rate as the tile, so it decouples the unit from the wood, which does expand and contract. One thing I learned just recently, is that the cbu in its differential expansion contraction from the wood under it actually pulverizes slightly around the attachment screws and that is why the tile/cbu unit doesn't crack (if done right). Make sure to use the special fiberglass tape made specially for cbu for the joints of the cbu. That reinforces the joints and makes it like one monolithic mass - much appreciated by the tile and grout!