I am attempting to tile my tub surround and this is my first at this. After ripping out the drywall and batting insulation I realized that insulating behind the tub itself is going to be a problem. I have already decided to go with HardyBacker and Regard,but the tub is directly against an outside wall and I'm not sure how to insulate there. I had decided on packing as much batting in the cavity behind the tub,then place a sheet of drywall or such and fill the gap between it and the exterior wall with spray foam ,but after talking to a friend I decided to use sheets of foam rated at R-10. Then seal of that area with caulk or something,then insulate the wall from there up with batting. My aquestion is: I know it is important not to create a double vapor barrior. Will using the same foam board behind the HardyBacking all the way up cause problems? I want to use the Redgard to prevent moisture/vapor from getting behind the tiles and causing them to come lose. Thank you.

Hi Firsthome

Build the wall out with 3/4" strapping every 16" on center. Fill between the strapping with the R-10 foam. Install 4-6 mil. Sheet plastic over the foam/strapping and you should be all set on that.

Install tub (insulate behind tub in open cavity behind/under tub) and then install the hardibacker board and redguard as normal.

Mark

Hi Firsthome

Build the wall out with 3/4" strapping every 16" on center. Fill inbetween the strapping with the R-10 foam. Install 4-6 mil. sheet plastic over the foam/strapping and you should be all set on that.

Install tub (insulate behind tub in open cavity behind/under tub) and then install the hardibacker board and redguard as normal.

Mark

I have neither the skill nor the experience/knowledge to take issue with your advice on a vapor barrier on both sides of the Hardbacker,but I have read "heated" discussions on that subject.

I did not advice a double vapor barrier... just a vapor barrier over the R-10 foam... ;)

I did not advice a double vapor barrier...just a vapor barrier over the R-10 foam...;)

But,the Redguard is a vapor barrier meaning that the Hardybacker has a vapor barrier on both sides... 4-6 mil. Plastic on one side and Regard on the other. Perhaps I'm not understanding you correctly and I know you are trying to help me and I appreciate that,but would you please explain where my thinking is flawed? Bill

No flaw in your thinking... missed the redguard part and was only speaking to the concrete wall. Proceed without the vapor barrier just like you thought!

Mark

Thanks Mark. Getting ready to paint on 1st coat of Regard. I used Versabond for cracks and seams... after taping. Man,that stuff is hard on sanding products! Went from sandpaper to the foam sanding blocks to the screen sanding products. Even the screen stuff rips in short notice.

Ready to start tiling and have a couple of questions. Hopefully someone is online now so I can proceed. I measured the center of the back wall,an outside wall that the long side of the tub sets against. I found 2 problems there I'm not sure how to deal with. First of all,both adjacent walls lean in,a total of nearly 1/4". At least they lean at the same pitch because the top centerline is plumb with the bottom centerline. Should I just ignore that and tile as though all was plumb? Secondly,the tub is out of level about 1/8" from one end to the other. Should I set the tiles level with the tub or with true level? Also,I'm using Versabond setting 3x5" ceramic tiles...very lightweight. Do I need to do the board halfway up as I've seen in videos to keep the tiles from sliding down or can I just start at the bottom,go up halfway and take a several hour break on that wall,then come back to it? I intend to place some sort of 1/16 to 1/8 shim on the tub so the tiles won't slide. What is considered the ideal space there?The tiles I bought I think just bump together rather than using spacers. What I've done up to this point: Removed old drywall,insulated with 1 2" and 1.5" foamboard giving me a total of R17.5,then Hardybacker rested on tub lip,1 coat of Redgard mixed 4 to 1 with water,then 2 coats full strength Redgard,then a bead of silicone between the tub lip and the hardybacker.
I'd appreciate any suggestions members are willing to offer.

Bill

Hi Bill

You wouldn't believe the detailed answer I typed out for you, but then when I posted it the site kicked me out and erased all my work! I don't think there is anything more that I hate than that!! UGH!

Anyway, if you still need help let me know and I can retype it, but I am not retyping it if you have already done most of the work!

Hi Bill

You wouldn't believe the detailed answer I typed out for you, but then when I posted it the site kicked me out and erased all my work!! I don't think there is anything more that I hate than that!!! UGH!!

Anyway, if you still need help let me know and I can retype it, but I am not retyping it if you have already done most of the work!

I had that happen to me,too. After typing (one-fingered) a long message I tried to post and discovered I got logged out and my message was gone. Thanks for the effort,though,massplumber2008;3393784. The job is halfway done. Whether it's done right is yet to be determined. Bill