I am tiling my bathroom and in the process of re-tiling the shower stall. I removed the old plastic liner there and now some of the glue remains on the greenboard. Also, some of the green part of the board is ripped of from when the glue came off with the old liner. Some of the paper is flakey in spots. I pulled off some of the loose pieces, but there is more. Now, I‘m an amateur. I was told to use some grout sealer to go over the greenboard. However, since there are flakey pieces of paper from the greenboard on there still, should I simply remove as much as I can before sealing and tiling? Will the seal glue these flakey pieces down and make them secure for tiling? What is your advice? Many thanks!
First of all, remove the greenboard that was under the tile. Replace it with cement board-that's a MUCH better subbase for tile. The peeling you experienced with the board that's up will cause you problems down the road. If you can't remove the greenboard, then your best bet is to sheet over the greenboard with 1/4 cement board, available in the flooring department at Home Depot. You will need to transition the tile where it meets the drywall outside the shower. In no case do you want to apply tile to the damaged greenboard. It will not last.
I think number 3 is your best option although cement board is not a moister barrier.You need to put a water proof membrane behind it. You can use 1/4 inch cement board and replace the green board with thinner green board.or you can use a paper barrier with 1/2 inch cement board
If you have gone that far, I would either tear out the greenboard and replace it with cement board, or you might be able to cement board right over the greenboard. The cement board will outlast the next 50 familys that will use that bathroom. It is great stuff, well worth the effort. Don't try patching the greenboard, it is not worth the effort. Do it right and be done with it forever.
you really should just replace the green board with wonder board.Grout sealer does nothing on drywall,whoever told you to do that is full of ****.grout sealer is for grout joints.Sealing is done AFTER tile is installed and grouted.If you leave the green board,just scrape the old glue off with a putty knife,and any loose paper,gently remove it.If there are gaps or gouges in the drywall,fill them in with joint compound ,let it dry and sand off any high spots. Installing cement board over existing drywall is not a good idea,it creates a space between the two for moisture and mold.And it creates a higher edge at the shower sides where tile edging is needed,and it will not work properly.
I have to agree with answer 1. I tile every day of my life, and while greenboard certainly should be used for the balance of a bathroom, I stopped using it around tubs and showers, years ago. Concrete backer board is an industry standard, is not more difficult to install, and actually aids in tile/mortar adhesion properties. While you have the walls gutted, you might add a vapor barrier as well. The issue with patching over the damage is that it may become just as degraded as the original substrate, and I suspect cause you to be unhappy. Steven Wolf Just my two sense
