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mkeith 05-11-2008 07:25 PM

Wonderboard over drywall?
I am new to this site and thought I would give it a try.
I am renovating our bathroom and tiling over the tub. We live in a mobile home that is not going to be moved as it is on a foundation.
( I keep saying...I'm never moving again and I really mean it as we have been here now for 9 years and the bathroom is the only room we haven't renovated yet) I put new shut offs behind the shower and am now in the mist of removing the tub and surround. We are picking up a fiberglass tub this week and I want to do a ceramic surround.
My question is... Can I put wonderboard right over the drywall that is behind the current plastic surround? If so...should I put a vapor barrier between the wonderboard and the drywall?

Thanks for all the advice and I look forward to using this site throughout my project!

Termite 05-12-2008 08:35 AM

Probably not a very good idea. You should remove the sheetrock before applying the wonderboard. That wonderboard needs to be secured right to the studs.

You can install a moisture barrier behind the wonderboard if you like. I usually use 15# felt, overlapped horizontally.

mkeith 05-12-2008 05:55 PM

Thanks, I got screws that are long enough to go through the cement board and the drywall into the stud. My handy dandy stud finder is a wonder and will save me alot of time. I will be putting up some poly I think it is 50mil between the two. I am planning demo tomorrow and hope to get the new tub and walls up. I would like to get the tape and thincoat on as well....but time will tell.

MacRoadie 05-12-2008 06:05 PM

So much for listening to thekctermite's advice.

Keep in mind, you are going to have to cut the bottom of the sheetrock away to secure the tub to the studs (you can't nail it through the sheet rock). The Code calls for that sheet rock to be moisture-resistant, and all manufacturers prohibit cut edges where the sheet abuts the tub deck. It has to be a factory edge.

Additionally, the fiberglass tub deck isn't going to be deep enough to accommodate a layer of sheet rock, a layer of wonderboard, thin set and tile.

buletbob 05-12-2008 08:09 PM

Mkeith, I would strongly consider taking Thekctermite & Macroadie"s advice.
Is there a reason why you are not gutting the drywall from the walls? People come to this site looking for professional advice but decided to do it otherwise.
Please forgive me if I misunderstood your Post .
I did not reply to this to bash you, Just believe in doing things the correct way if your going to be redoing the bathroom anyway. Sounds like your going to have a double vapor barrier Behind the existing drywall and then behind the wonder board??? Good luck!

send_it_all 05-13-2008 02:16 AM

Look at the bright side. He'll have something to do next year. I hear mold remediation is very, too.

Termite 05-13-2008 07:46 AM

Wow, its as though I never even replied. :huh::no:

Sir MixAlot 05-13-2008 06:50 PM

A poly vapor barrier behind the wonderboard and over the existing drywall is a bad idea. You will be trapping moisture. :no: Like previously stated MOLD ALERT!!!!!!!!!!!!:wallbash:

CowboyAndy 05-15-2008 06:38 AM

I wouldn't be surprised if they don't come back... they didn't get the answer they wanted to hear!

Besides, why would you want to have the cement board OVER the drywall... where the tile will end is going to be 1/2 thicker than the drywall, how the heck would you transition that?

mkeith 05-15-2008 07:51 AM

kctermite I took your advice...(that is why it took so long to reply) Its interesting to see the difference in the construction of a mobile home vs a conventional home. Demo took me longer then expected. The plumbing didn't line up. It took an extra day just to get that fixed. I needed to put a strip on the stud to bring it level with the lip of the tub. So after three days of demo and plumbing I am finally ready to put the wonderboard up.
I am sorry if you didn't think I listened...I did...I am getting too much advice from family and friends on this end and I just need to concentrate on what is going to give me a long lasting and less labor intensive result in the long run!
Thanks to everyone that respnded.:)

Termite 05-15-2008 09:09 AM

Glad to hear you did it right! :thumbsup:

Sir MixAlot 05-17-2008 10:23 AM Glad you to see you that you made the right choice.

sevver 05-17-2008 10:39 AM

Sometimes people scare me. Burying and overlaying potential problems when there is no savings, the material is still there, the labor is still there, the only savings is MAYBE time, but it never seems to work out that way. I just saw this post and commend you for doing it right.

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