Durock installation on 16" center for shower

[benromach]

Hi, I am new to this site. In my search for answers, however, I could not find an answer I needed. I am remodeling a bathroom in my house, took the walls down to the studs, and I am replacing a bathtub with a shower 60"x32". I installed Durock on the long wall (60") and followed the instructions- but the instructions from USG do not indicate I should install blocking at the seams between the studs where the Durock is not supported- horizontally. Will this be OK once I install the tile (with thinnest) and tape the seams? The tile is marble, 2x4". Right now- before installing the tile, it seems a little flimsy.

Thanks- Benro

[tileman2000]

Hi Benro,

If the walls seem flimsy than by all means add the blocking. Marble is fairly heavy and you want the walls as sturdy as possible.

Are you planing on a vapor barrrier behind the Durock or a waterproofing for the surface?

[cx]

Welcome, Benro.

For 16" stud spacing I believe the majority of backerboard manufacturers don't require blocking behind the seams.

Unfortunately, USG has "improved" their website to the point where I could not find installation instructions for their product.

Perhaps their rep will stop by and answer your question and maybe tell me how to find installation instructions on the website.

You are using the Next Gen board, yes?

[benromach]

Tanks for the feedback! The walls are strong- the seam can be pushed and flexes some. The Durock installation says nothing about the seams when oriented this way on 16" centers.

It is NextGen and I am using Ditra on the outside for waterproofing. I will try their rep and see how they respond. Thanks again!

[Tiger pilot]

Benro and CX;
USG in in the process of redoing our entire website and unfortunately it seems some Non installer folks are doing the computer work so we are struggling to make it make sense the way we all think. The installation instructions should be found (at least I found them) in the technical info section under Durock. Please bear with us and we promise to continue working on the site as quickly as possible.
Now to the answer - not sure how or which direction you are running the Durock, but the seams should naturally fall on a stud if the studs are 16" o/c. If that is not the case, then by all means block the seams as this will always be the weakest part of the installation. Waterproofing (while a good idea) will not help strengthen this so it is critical that you have some type of support behind each and every seam and that you are able to nail or screw the board every 8" o/c in the field and 6" on the edges - including seams. These instructions are directly out of the TCNA Handbook but do accurately reflect our USG instructions also.
I thinK (maybe) I uploaded the file that should give you what you are looking for. Either way you can email me at: Srausch@usg.com with further questions or I will then send you the file
thanks CX for bringing this to our attention.
Steve

[Hammy]

Steve, in looking at the link you provided.......... In using 2 - 3' x 5' for the back wall of a shower...... Solid blocking is required along the long axis of the BB?

Hammy

[Tiger pilot]

What that means Hammy is that you need a stud along a seam, which is how the walls usually, normally line up. All we are saying is to support the board along the edges and every 16" between the edges. This is totally in line with the TCNA Handbook specifications for any and all backer board units.

[cx]

I'm thinking there is still some misunderstanding here, Steve.

We all accept that the edges of the boards that fall on studs will be fastened there. But there will always be horizontal edges spanning between the studs, yes? A 14 1/2" space between studs where one or two edges span across that gap.

Do you require horizontal blocking to be added behind those joints was the initial question.

And I used to be able to find that same installation brochure you just posted any ol' time I wanted it. I'll try again on your site.

[My Dream]

Am I to understand that you would install Durock like you would normal 1/2" drywall on 16" OC?

[cx]

No, Frank, you're to understand that you would install Durock like it says in the Durock instructions.

[My Dream]

Now don't I feel stupid. ,

[Hammy]

CX, like you I guess I'm still confused about the horz. blocking. I havent had time to research the TCNA handbook to confirm what Steve refered to.

Hammy

[Tiger pilot]

OK guys, as CX suggested I may still be confused/misunderstanding here - problem with getting to advanced age stage!
My mental picture here is the studs on a tub surround - you would normally use 3x5 pieces of Durock 1/2" - that is what I am picturing. Since you want to run the board the length of the tub - then stack the 2nd piece on top you would have that 14" span between the studs but the board would/should be supported and nailed on each stud and then yes you MAY want to use blocking between the studs - especially if you are going to use heavy tile/stone/marble. It would not normally be required HOWEVER you, as the professional with eyes on the job site actual conditions MAY decide to block that entire edge. If I were working with stone/marble I certainly would, but then I'm somewhat old fashioned anyway.
Required?? We say USG follows the TCNA guidelines, and I will tell you point blank, there has not to my knowledge any failures as described reported to USG. The 14" "gap" if you will, between the studs, in normal tile install would not cause a problem as long as you taped the seams (as is supposed to be happening always anyway) but if you have a failure (cracking of tile or grout) I would suspect that no tape has been applied - and quite frankly, that could happen even on top of a stud if the board isn't screwed or nailed in the proper manner and allowed to "hinge or pivot" as we have sometimes seen.
Am I now understanding and saying what makes sense to everyone?? If not, as CX knows, you won't hurt my feeling to try to re-explain it to this dumb german guy from Atlanta! Two strikes against me!!
Sorry that I've made such a simple question/post so complicated.
Steve

[Hammy]

Ok Steve, I think I finally got it. You are "suggesting" horz. blocking in the rear shower wall it is "not required" by TNCA. cement BB do not suggest this blocking.,

Hammy

[tilerite]

Ditra over cbu?? Seems like overkill to me.