hardibacker screws [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


View Full Version : hardibacker screws

08-29-2004, 09:36 PM
I did a search and found some information on screws not being completely flush, but still don't have a difinitive answer. I used thinset and the recommended screws to attach hardiboard over 3/4" OSB. Some of the screws are not completely flush, but most are and some are even countersunk. The screws that are sticking up, are just slightly above the surface. If you run your finger over them you can tell they're not flush, but it's small enough that it would be next to impossible to even measure the height above the surface. It's definitely less than an 1/8 of an inch and probably even less than 1/16". I was trying to use a punch to flatten them down, but it's pretty tough. I got a little concerned because I layed down a tile over some of the non-flush screws and it rocked just slightly. Will the thinset over the hardiboard be enough to take care of the problem?


Sponsored Links

08-29-2004, 09:41 PM
Hit them with a hammer! Leave them up and you will be fighting your instalations all the way.

08-29-2004, 09:59 PM
That's what I thought. They are really hard to budge. It took a lot of pounding just to get one screw flush. I since bought a more powerful drill and they are going in much easier now. BTW, it seems Wonderboard would be a little easier to sink screws since it doesn't seem as dense. Am I right?

Thanks much,

Chris D
08-29-2004, 10:32 PM
I too am having the hardibacker screws not sinking flush. No luck with the hammer. I can go the Dremel tool route to cut off the heads of the worst offenders. How many screws do I need to drill into the Hardibacker? The Home Depot tile guide says 1 every 4 inches. That seems excessive, but what do I know. The guide also said to put a coat of thinset under the cement board. I read elsewhere in this forum that some tilers lay tile directly on the plywood. What gives?

Here's my question along the "How level is level" vein: If I am laying down a WarmlyYours heating pad (which adds about 1/8" on top of the hardibacker, do I still need to be concerned about the screws? Or do I need to be even more concerned about the screws?

Chris Dart

08-29-2004, 10:47 PM
You need the mortar under the backerboard. It will make or brake the floor.
Screws: Do just what Hardi tells you. If the screws that you are trying now don't work well get another brand and try them. I have had good luck with the Orange ones. and a driver with a LOT of power.

Use Fiberrock and you can staple it with a a wide crown staple like used in a Senco M-2

08-29-2004, 10:49 PM

I shouldn't be making suggestions because I barely know what I'm doing, but I hit the offenders with a big punch and after a few million whacks and a great cardio workout, I got most of them flush.


08-29-2004, 10:59 PM
From your description, Aaron, your screw heads might be low enough that the thinset will take care of it. However, as Jerry points out, it's a hellofa lot easier to deal with them now than when you're trying to set tiles. If in doubt, mix up some thinset and set a tile over your worst offender. If it's OK, don't worry about them. But a good smack with a big pounder should flush them a little better. This is not something you wanna be doing with a lot of the screws, mind ya, but if there are just a few high ones, it'll help.


Listen to Jerry. :)

08-29-2004, 10:59 PM
Look, don't worry about it. 1/32" out of flush is nothing to get bent out of shape about - pardon the pun. I have two bathrooms both sheeted in 1/2 wonderboard. I went through almost 10 boxes of Rock-On screws. Hardly any of them are flush, and trying to back them up, and tighten them down again often resulted in me stripping the head. Once the thinset goes down you won't even notice, and I had to do some heavy duty screeding to get my walls flat with a straight edge. They barely caused any trouble. I had more problems with the out-of-plumb and out-of-square sections of wall to worry about that.

08-30-2004, 06:06 AM
I had the same problem with my floor install. I used a 3 pound sledge hammer. It took about 2 good blows and it sunk in just fine. Definately make sure that they aren't too proud, it will cause the tile to be high on one side. Boy will you be pi$$ed when you see that one tile sticking up, knowing that you should've fixed that screw.

Spoken like I've made the mistake before, huh?

08-30-2004, 07:21 AM
Thanks for all the advice. I think I'll go to Home Depot and buy a bigger hammer.


08-30-2004, 08:15 AM
Hi Aaron.

Going forward, I'd switch to galvanized roofing nails. Setting screws flush in Hardibacker is a royal PITA. Here's a quote from the James Hardi website, Hardibacker FAQ"

Q: Why can't I get the screws to sit flush with the Hardibacker?
A: The screws that you are using do not have the power to rout out the material in order for the screw head to sit flush. Be sure to use the specified screws (1-1/4" No.8-18 by 3/8" HD Hi-Lo S or S-12 for metal studs, ribbed phil wafer head, self drilling, corrosion-resistant screws). If you continue to have difficulties, we recommend switching to 1-1/4" galvanized roofing nails..

For additional info. on Hardiboard, visit Hardibacker FAQ (http://www.jameshardie.com/backerboard/homeowner/faq.php)

08-30-2004, 08:31 AM
I'm using Rock-On cement board screws (#9 x 1-1/4). I'm wondering if my drill is not powerful enough. I just bought this Craftsmen drill, but it's only a 5.0 amp and 0-1500 rpm's. I'll try some different screws as suggested. Do the screws need to be fastened immediately after laying over thinset or can they be down later? I put the screws in right after I glued it with thinset. I've only done one board so it's not too late to do the rest correctly.


08-30-2004, 08:51 AM
Aaron, I think your drill is fine, the screws are fine, setting the screws while this thinset is fresh is the correct way. Getting those screws to set flush is still a PITA :bang: :bang:.

If you want to pre-drill holes with a countersink bit, that's one way. The other way is to follow Hardi's advice and switch to nails. :)

08-30-2004, 09:05 AM
I like the pre-drill idea. Do you have a recommendation on what size bit to use? Obvoiusly the pre-drilled hole should be a diameter that will allow the screw to go in easier while fastening the board down tight. I'd rather not experiment, so any advice would be appreciated. Again I'm using
#9 x 1-1/4" Hi-Lo screws by Rock-On. I'm not sure about the countersink bit. Would I drill the whole first and then use a countersink bit over the hole to make an indentation the size of the head so that it can screw in flush? Please exuse the ignorance.


08-30-2004, 09:38 AM
5/32" pilot hole +/with a countersink cutting head will work.

Edit P.S. Just for clarification, I'm only talking about drilling into the backerboard now, not the stud.

08-30-2004, 10:15 AM
Yeah, your drill is ok. I'm using an 18v set on the highest torque setting so it won't "break" at a specific amount of torque. I know it was doing the job because I couldn't rotate my wrist for a few days afterwards.


Steven Hauser
08-30-2004, 10:24 AM
Nails are faster and frustration friendly.


Chad Brown
08-30-2004, 10:35 AM
The green Durock screw sold at Home Depot work much better. For one, they are phillips head and not that ridiculous square head that never seats properly. They are also a much flatter head and will flush out much easier.

08-30-2004, 11:19 AM
Rock-On screws. That's what I've been talking about. They don't sit perfectly flush, but they do stand up about 1/32". Not enough to complain about...

Gil Smith
08-30-2004, 11:28 AM
An impact driver makes short work of setting screws in Hardibacker. With 900 in-lbs of torque I haven't found a screw yet that I couldn't drive flush in a matter of seconds. Have to be careful not to "countersink" it right thru the board!

I've seen the advice before to drive the screws flush with a hammer, and frankly I don't think I would do that. It's one thing to drive a nail because it's depending on skin friction around the shank to hold it down, but when you whack a screw down with a hammer all you're doing is shearing the material around the threads, reducing the holding power of the screw. You may as well just remove the screw and leave it out, IMO.

08-30-2004, 12:04 PM
Some of the screws have stripped heads so I was unable to remove them. I pounded them down with a big punch. Should I put another screw next to the pounded ones? We're not talking about screws pounded down 1/4 on inch. Most of the offenders were just barely protruding. The hardibacker seems like it's on very solid.


08-30-2004, 09:07 PM
Seems I read somewhere that Hardi recommends that when a fastener is in doubt to put another one 1" away from it. If you do that, to avoid having another with a protruding head I'd carefully pre-drill (thru the Hardi ONLY) with a bit slightly larger than the screw threads. This will keep the threads from engaging the Hardi and lifting the board away from the substrate. Slightly countersinking the pilot hole with a bit the same diameter as the screw head wouldn't hurt either.

08-30-2004, 09:16 PM
Geeze, what a screwy fuss. 22 posts on screws thus far and still going strong. If y'all used nails, y'all be grouting by now. :D

08-30-2004, 09:27 PM
What Mike said. :D

James Bontrager
08-31-2004, 04:58 PM
I had a post earlier about this, and have decided that from now on I will be using nails. From my experience you dull out a counter sinking head in short time (on hardibacker). I used a 1/2 drill bit (cheapest I had) to make the counter sink, and had no problem with the heads sitting flush. I just didn't like taking the time to go through all of those steps. A lot was explained in the previous post I had Its subject line was "securing cbu".

Good luck, Jim

08-31-2004, 05:19 PM
Ok, as much as it seems like a bad idea to nail down backerboard, sounds like nailing the hardi is much less frustrating than screwing. That being the case, can I use my roofing nailer to knock it out more quickly? The coils of nails don't come in ring shank, but Hardi's site does not specify ring shank. Thoughts?

08-31-2004, 05:48 PM
My problem was solved when I switched from phillip heads to the square heads. They're green and made by Buildex. It's not "rocket science" but it seems there is a feel for putting in these screws so they end up flush or below the surface. I definitely got better once I learned how much preasure and speed on the drill I needed to avoid stripping them. By the last half of laying down hardiboard, I was drilling like a pro--OK maybe not, but it did get easier.


08-31-2004, 07:03 PM

Don't need ring shank. Need corrosion resistant; HDG best, don't even come in ring shank.

Big Wagon
08-31-2004, 07:37 PM
I'm with Aaron. I just put in Hardibacker using the green, square head "Backer On" brand screws that they sell at home depot. I used a 14.4v Makita cordless, and I had no problem getting every screw flush. No stripped heads. I drove just under 200 screws with not a single problem. In fact, I had to be careful not to overdrive them right through the board. I think the square head must make the difference. Oh, I turned off the clutch on the drill and used The Force to get to proper depth. Thanks Yoda.


08-31-2004, 07:45 PM
Big Wagon has The Force? :eek:

09-01-2004, 09:48 PM
My husband and I are tiling our first floor and have just screwed down the Hardi backerboard. We found our first drill did not have enough power to set the heads down into the board. We bought a better drill and we were able to drill the screws right down with no problem, in fact, we had to make sure we didn't screw them all the way down to the subfloor. We used the Hardi backerboard screws. I hope this helps. We are just beginners ourselves. Good Luck!

Big Wagon
09-02-2004, 09:28 PM

The Force is at my command only when using power tools--no good when working with thinset, trowels, and other tile tools. See post on recent failed mosaic installation "Mosaic Madness" for example. :cry:


09-02-2004, 10:25 PM
I saw that, Dave. :(

I've got just enough hours on the handle of a trowel to know that the only Force that's with me is the economic one that made me take up the trowel in the first place. I think it takes a long time for the Force to find its way into a trowel. Or maybe it got lost in one of my chisels or saws or something. :D

04-24-2006, 09:51 PM
I had to lay the hardibacker when I retiled my bathroom.

I used self-tapping, flat head, square bit screws and had no problems getting them flush.
The square bit is nearly impossible to strip out.

04-25-2006, 07:04 AM
I used "backer-on" made for hardibacker board. My cordless drills did not have enough power to do very many screws. My Dewalt drill was to powerful and stipped them out. I finally used an old cheapie Black and Decker and it worked the best but even then I had trouble stripping out the heads of the screws. About every 3rd screw I used either would not sink and or would strip out. I would have to say that screwing this board was the hardest part of the project.

05-30-2006, 03:05 PM
On my kitchen, I used the green Hardibacker screws and my Makita screwgun. I bought some cheap #2 square Dewalt bits for it, and they didnt last long. I switched to using the included bit in the Hardibacker boxes and my 18v Dewalt drill and had no problem, except for driving too deep. I set it at the lowest speed, and had very little problems. If your screws are stripping out, I would check out the driving bit and make sure the corners are not rounded off. This will keep the screws from going flush when the pressure gets high on the bit.