securing cbu [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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James Bontrager
08-21-2004, 04:48 PM
I generally use hardibacker for my cbu, and normally use decking screws to secure it (w/thinset). I use an auto feed screw gun (Senco). My gut feeling is that screws are better than nails, decking screws are cheaper than cbu screws.....but roofing nails are approved; which is much less costly, and probably just a bit slower than the screw gun. What are you all using and why?

Thanks, Jim

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Rd Tile
08-21-2004, 06:19 PM
Roofing nails, getting their screws to countersink is a PITA.:)

08-21-2004, 07:13 PM
me2 :)

08-21-2004, 08:20 PM
You can't use the regular roofing nails. Use the ring shank ones if you're going to use nails at all, and they have to be 1 1/4".

James Bontrager
08-22-2004, 10:38 AM
Thanks for the quick replies.

With the dura spin screw gun I don't have "much" trouble counter sinking the screw heads when on plywood, osb is another story, might as well pre-drill every one.

Back on topic though, is there anytime that you would need to use screws instead of the roofing nails, and if not any idea why they even make screws for the cbu?

Cobalt: Are you referring to underlayment nails? If so, I beleave that they are prone to rust, and are not recommended.

Thanks again for your time and advice. Jim

08-22-2004, 11:09 AM
Hi Jim:

I copied this from the JamesAHardi website. Fastener recommendations for Hardibacker.

James Bontrager
08-22-2004, 11:26 AM
Mike; thanks, I have been to the site, was wondering what others were doing as far as using nails vs. screws, and why?

Thanks again; Jim

08-22-2004, 11:35 AM
Yeah, several different ways to tie a shoe, eh Jim. Me, I use high-low screws for Durock and nails for Hardibacker. Not saying that's the best way, just what I do.

John Bridge
08-22-2004, 01:41 PM
Mike, I'm 63, been tying my shoes the same way since I was about four, and now you're tellin' me there might be a better way? :D

08-22-2004, 02:52 PM
There most definitely is a better way to tie a shoe JB, learned it all in the Coast Guard. And if you behave yourself this week I just might let you in on this sailor's secrete. :D I learned it well too...I'm 63 yrs. 'ol as well and can still 'member it.
Now where did I pewt dem shoes?? :uhh:

James Bontrager
08-22-2004, 11:17 PM
What is a Hi-Lo screw....I have my fantasies, but I doubt if its the same thing.

I'm 54 and was getting confused as to whether it was left over right of vise versa, so I went to Wal-Mart and bought slippers, ended that problem.


Big Splinter
08-22-2004, 11:56 PM
Id like to know about them hi-lo screws.??????

08-23-2004, 05:37 AM
Hi-Low screws are specially designed for cement backer board. They have a bi-level thread to help them hold well without breaking the board, and special ridges on the bottom of the flathead screw-shaped flange that helps cut into the board so that you can set them flat without a major pain (if you get them started straight!). They are corrosion resistant and hardened specifically for their task. As with many special purpose item, they cost a little bit more than a generic item, but they seem to work well from my limited experience.

08-23-2004, 06:21 AM
Jim, are they like the USG Durock brand screws or the Buildex Rock-on/Backer-On equivalent?


08-23-2004, 07:04 AM
As far as I know, they are probably equivalent. The Hi-Lo ones are what is available at Home Depot.

08-23-2004, 09:47 AM
I used those to hang my wonderboard. Sometimes they don't want to go absolutely flush, and sometimes they want to continue going right through the board. Use a variable torque screw gun, and plenty of patience, and they'll work fine. I did end up with a sore wrist, though...

On the roofing nails thing, yes they have to be corrosion resistant.

08-23-2004, 10:03 AM
Jim, are they like the USG Durock brand screws or the Buildex Rock-on/Backer-On equivalent?


Those are hi-lo screws and they are the type you want to use.

James Bontrager
08-23-2004, 10:13 AM
Which brings me back to the original question.....why pay the $ for those screws if roofing nails will work and are listed by the manufacturer of the cbu as an appropriate fastener?

I've used them before (didn't know that they were Hi/Lo), they generally didn't set flush, and are expensive.

Thanks, Jim

08-23-2004, 11:57 AM
Hmm... I just used the HardiBacker screws that were hanging on the display next to the HardiBacker at The Home Depot.

No thinking involved... just like I like it. :crazy:

08-23-2004, 05:06 PM
Jim, one reason I can think of, if you're like me, can't hammer worth beans. Its easier for me to use a screw gun than it is to hammer a nail in. I'd hate to think of blasting a hole through one of them spensive sheets of cbu. Murphy and all that you know. Which brings on this question. Would one of them drywall dimplers work on cbu, i.e. drive the screw to sit flush and not dig in? Anybody use an impact driver instead of a screwgun, drill, or drill/driver.


James Bontrager
08-23-2004, 05:35 PM
I got the Senco dura spin that is corded. The drive is adjustable, and once you have it dialed in it is blazingly fast. If I had 2 of them a helper would be busy just loading the strips. I got mine on ebay brand new for 75.00.

I had been using it to put down cbu, and haven't had any problems, but as your reference to "Murphy" he rides right on my shoulder it seems, and I am afraid that if there ever is a failure it would be attributed to the fastener that I am using not being listed as acceptable for hardi-backer. In my mind I would think that decking screws would be better than roofing nails, but what do I know.


John Bridge
08-23-2004, 07:43 PM
I don't know. I do know that the backer board "floats" over the subfloor. It's not a part of it. Backer board acts the same way membranes (or mud beds) do in that they uncouple the tile field from the subfloor. Thinking of it that way, it seems to me the galvanized roofing nails would be just fine. They do have the advantage of having much larger heads than any of the screws we've talked about here. That surface holding power seems significant to me. Mind you, I'm certainly no backer board pro. ;)

08-23-2004, 08:21 PM
I would think that a drywall screw drill would work as well. They are adjustable in depth. The non-adjustable attachments for "standard" drills might (try) to drive them deeper than you'd want. I've got some to put up, and I'll dig out the drywall drill. May not be for awhile, as I've got other things that need to be done first. The electricians finished today - had three of them running around for awhile. Don't want to see that bill when it comes, but since this is a multi-family dwelling (condo), code says I can't do it myself. I'm sure they did it faster than I could, though.

James Bontrager
08-24-2004, 05:49 PM
John; that answer was pretty good, I haven't really been thinking of cbu as a decoupling membrane, and I guess that was a flaw in my reasoning. Still don't see the need for the cbu screws even more so now.

Thanks all for the many responces. Jim

08-24-2004, 06:22 PM
They are like broccoli need for that either. :D

James Bontrager
08-24-2004, 08:36 PM
Now that is quite the insite!! However.....I like broccoli, put some cheese on it, and you are almost right up there with fried green tomatoes!!

:bow: Thanks again for the many replies, next install I will be nailing. Just had a would be the same for a floor or wall, correct?


08-24-2004, 09:02 PM
That be a Yes from me Jim, 'cept on a floor you also want thinset under it.

Too bad about the broccoli. :D

How 'bout brussels sprouts?

James Bontrager
08-24-2004, 09:47 PM
Understand that thin set is needed on the flooring end, appreceate the thought though. Have thought that I knew what I was doing previously (a lot of times), sometimes education really slows the job down.

Now about them brussel sprouts, they are ok every now and then...Now them fried green those are right up there with the Morel mushrooms..Fry up some bacon for the grease...dip them in flouer that has been spiced up......I'm getting hungry and it's bed time, sounds like tomorrows supper.

Thanks again. Jim

dave on his knees
08-25-2004, 03:14 AM
Hi I never use ring shank roofing nails, actually I have never seen them around. I use regular galvinized roofing nails by hand well I do have to use a hammer to get then flush with the floor :) . Anyway, anybody use a roofing air gun to put their nails in cbu?? Also, it is unmodified thinset below hardi and durock, right?? Thanks david

John Bridge
08-25-2004, 05:26 PM
Yes, I think the best nails are the old fashioned hot dipped galvanized roofing nails, the ones with the occasional galvanized bugger on them. ;) Hard to find nowadays. You almost have to go where roofers buy their nails.

I like "trees," and I like "clouds," too. And Morell mushrooms are a delicacy we simply cannot get down in these parts. Oh, I imagine there must be some epicurian place around that sells them, but common folk won't shop there. ;)

James Bontrager
08-26-2004, 05:42 PM
:topicoff: :topicoff: :topicoff:
Check ebay, we had a lousy season here this year, but I found someone in Canada selling dehydrated @ 15 a lb dry....What a deal.....I also bought some fresh, that came within 5 days @ 20 a lb. If I remember right they came from North Dakota.

Ebay is the place to shop!!!!

Keep getting kicked off from my ISP (I think that they are trying to move me to DSL), so I may have double posted....sorry, but am having mushrooms with supper tonite.....oh yes