Durock installation [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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09-14-2004, 01:21 PM
Please help fast. I have a floor contractor about to install a huge amount of tile in my house. He will be using 5/16 durock underlayment. There is descrepancy about what is acceptable means to attach the durock to the subfloor. The installation manual at the usg website specificall says to use roofing nails or durock screws, 8" oc. There is another page at that site that says 1/4" x 7/8" galvanized staples are ok. I called teh support line at usg and teh guy said definitely DON't use staples.

Also, the floor contractor says they put the smooth side of the durock DOWN. That is contradictory to EVERYTHING I've read about durock. The usg rep said this will void warranty, too.

Please advise.


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09-14-2004, 01:53 PM
Hi Randy and welcome to the Forum.

I think the quickest and best thing for you to do right now is to go out to the USG website and print out the 11 page installation manual for Durock panels. It's quite specific and complete. And remember, when advice and opinions differ, always follow the manufacturer's instructions. You might even want to print out another copy for your contractor.

Here a link to the Durock literature section. In the middle of the page under Cement Panels, click Application

Durock Installation Manual (http://www.usg.com/Product_Index/_product_index.asp?vFamily=3&vBrand=2&vProdCat=0&typ=products&sp=true)

09-14-2004, 03:32 PM
Thanks Mike, I already printed out 2 different manuals from the site and they were consistent but there was another page there that indicated 1/4"x 7/8" galvenized staples were ok for use in this application. I emailed the usg folks about this discrepancy and they are reporting this to the durock product manager for a ruling. They also responded that the smooth side of the durock was specifically for mastic/adhesives and the rouogh side was for thinset mortar and such.

What I'm really after here is real life experiences from the experts. How important are these two things? Are they show-stoppers?


09-14-2004, 03:43 PM
"The Board is smooth on one side for adhesive applications, textured on the other for thin set applications."


09-14-2004, 07:29 PM
Well, since Durock says the board can be installed over mastic instead of thinset, I would say your contractor is correct about putting the smooth side down. He's certainly gonna use thinset to lay the tile on top, eh? I've got no idea why the rep would say puttin' the smooth side down would void the warranty. :confused:

Educational. I sure didn't know any of the CBU manufacturers authorized the use of mastic under their product on floors. :shades:

My opinion; worth price charged.

09-14-2004, 08:19 PM
I put down alot of durock and never heard that, of the smooth side up. I've seen others do it but it makes sense to me if you are sticking tile to it I would want the ruff up for better adhesion. l've never used mastic under it either. Always thinset. Roofing nails works well, use to use screws but that takes too long. The staple thing seems alittle shakey to me be if the company says it's ok then I guess it's ok.

09-15-2004, 08:03 AM
APOLOGIES! I was in a hurry when I first posted here and made an error. The contractor puts the smooth side UP, not down, sorry.

So from the replies so far, the contractor is definitely wrong in this aspect. How about some opinions on the staples?


09-15-2004, 08:21 AM
If you haven't already invested in the Durock, you may want to check out Georgia-Pacific's Densshield. It's available in the 1/4" thickness you need and should be easier to work with. Here's a link:


Does anyone on the forum have experience with this product?

09-15-2004, 08:37 AM
A quarter-inch crown staple in a cement-type backer board seems to me like a good waste of staples. Just seems like that staple would pulverize the board under it and you'd not have anything holding at all. Keep it from moving sideways, maybe, but won't be holding it down. I think it's a bad idea, but I've never tried it, either.

It'd be fast, though. :D

My opinion; worth price charged.

09-16-2004, 07:42 AM
FYI, I got a response from USG regarding the discrepancy of info on their site on the use of staples in durock. Staples can ONLY be used in countertop applications. For flooring, you MUST use roofing nails or screws. They supposedly have corrected the incorrect info at their site.


09-16-2004, 02:03 PM
I think some Left Coast Bodark Skull Yankee might have figured out somea this mess looks like three different USG products being discussed here, simuldamntaneously. ;)

1. DUROCK Underlayment Panels -- (5/16 thick);
2. FIBEROCK Underlayment Panels -- (1/4 & 3/8); then last but not least,
3. DUROCK Cement Board -- (1/2 & 5/8) the CBU near-in-dear to our hearts.

Randy man, if Im reading your post correctly, you be pewting down on your floor 5/16 DUROCK Underlayment Panels, that right? Its the only one that comes sized in 5/16 so that must be it.

Now I dont want to get into all the T & Cs along with all the Ifs, Ands, or Buts associated with all these different products because thats just too damn much typing and I prolly dont have that long to live. Besides that, I have to submit any writings morein 200 words to our Editor-at Large somewhere down there in Texas and hes been so cranky lately yall may not have that long to live til hes done mucking with my prose. So, having said all that.lets see..where were we.oh yes

I do have some time left to yap some more about the 5/16 DUROCK Underlayment Panels which are to be laid with the smooth side up and the only approved fasteners are screws and roofing nails, just like DUROCK Cement Board. Continuing on just a little bit more, the only one of these three products where crown staples are approved for use is the FIBEROCK Underlayment. Bet you 6 cans of Spam Randy, thats where you picked up on the staple bit.

Im outta breaft now so Im yielding the floor to next in line.


David Taylor
09-16-2004, 05:16 PM
Six cans? That's a lot of SPAM to be betting there, Mikey.... but I'd say your odds at winning are pretty good. ;)

Chris McNeal
09-16-2004, 10:39 PM
I use durarock installations almost every week if thats any comfort to ya.smooth side down hot dipped galvinized roofing nails or durarock screws are the only thing recommended. you can usually find a sticker on the up side of the board with installation instructions. I know this because I get tired of removing the stickers before tile installation which by the way are on every board. I guess the purpose for this is so contractors can get something right and go figure it still didn't help this guy. I'm sure he's pretty bright though just somehow over looked all those annoying stickers.anyway you'll find that gold deck screws with a square drive head instead of phillips works really well.they want break and it's less likely to strip the head out of them. oh did I mention there cheaper to. I wouldn't use nails there faster but I'm guessing your more interested in the quality of the job not the speed I would be.Durarock want warranty the deck screws but I wouldn't be affraid to use them at all. Just be sure he also uses thinset under the backerboard most contractors in my area don't and the installation want last. hope I was of some sort of help. good luck

09-16-2004, 11:04 PM

You're gonna hafta show me where they say to pewt the smooth side up, Mike. I just read through the installation PDF again. Says one side's smooth for adhesive, other side "textured" for thinset. Don't say nothin' about which side up.

Also says if a fella's pewtin' 1/2 inch or 5/8ths inch board onna floor for underlayment, he does it all-same the 5/16ths underlayment board.

My six of Spam is onna table. :)

09-17-2004, 09:53 AM
There is an installation guide and a Durock cement board specifications document at the USG website. Regarding the 5/16 underlayment (which is the only topic for this thread), both are consistent in that the smooth side is for adhesive materials and the rough side is for thinset mortar. I also called their tech support line and discussed this with a rep...he said the same thing. I submitted an info request at their site and the response was consistent again. BUT, there was another statement from another page on that site, regarding the 5/16 underlayment specifically, that said staples could be used in floor applications. I sent this url off to their support folks and they acknowledged the discrepancy and submitted this issue to the Durock product manager for a ruling. They responded to me later that this info was obsolete, said they would correct the problem and thanked me very much for pointing this out to them.

I did the original post prior to learning about the stapling so I could get experts input.

I got with the flooring company and discussed this issue at length...they got me another subcontractor to do the job right.


09-17-2004, 11:46 AM
I got with the flooring company and discussed this issue at length...they got me another subcontractor to do the job right. This is a good thing. :)

09-17-2004, 06:07 PM
CX, my post reference made to:

5/16 DUROCK Underlayment Panels which are to be laid with the smooth side up

is simply recap from Randys Post/what USG Tech. Support told him. Like you say, web-site documentation is no more that smooth side for mastic, rough side for thinset. Furthermore, the Submittal Sheet for DUROCK Underlayment & Cement Board states only approved fasteners are screws and roofing nails, pg. 1, para Installation.

My reference to crown staples approved for used with FIBEROCK Underlayment is documented in its own Submittal Sheet. http://www.usg.com/Product_Index/_product_index.asp?vFamily=3&vBrand=3&vProdCat=0&typ=products&sp=true

Open up the FIBEROCK Submittal Sheet then in that document you will find at least three references to crown staples being approved for use: pg. 3, para 2.1 Materials; pg. 5, para 3.3 Ceramic Tile Floor Applications; and pg. 6, para 3.4 Ceramic Tile Counter Top Applications.

We on the same page? :)

09-17-2004, 06:49 PM
I think so. :)