What kind of screw would I use for attaching 5/8" Durock to 18g steel studs? (yes 18g). I was looking at the Rock-On screws but they don't say anything about 18g... I do believe I need the 1-5/8" and not the 1-1/4".

In addition, what kind of screw would I use to attach 5/8" Durock to masonry brick (including a thinset layer in between)?

Do I have to predrill?

Thanks
Brian

 

They make dedicated screws for the Durock.
Cement Board Fasteners On ITW Commercial Construction - North America
Those Rock On screws look like the same thing. 1-1/4" should be fine.

For the Durock to masonry you're going to need Tapcons and you will need to drill them.

 

Thanks man...

So the gauge of the steel stud shouldn't make a difference on those Durock screws? (They'll work on 18g just like they will on 20g or 25g)?

-Brian

 

Thicker gauge studs will take more spinning to start the screw... only difference. 1 1/4" is sufficient.

 

Along the lines of what Pete posted, you want to look for 'High-Low' screws. The hi-low has dual threads of different diameters and grabs thin material very good.
Here's an example:
https://www.homedepot.com/p/Everbilt...0008/206949574

 

Rock on screws are high-low, specifically for cement board. He has the right screws.

https://www.homedepot.com/p/Rock-On-...3301/300662298

 

Very good, just wanted to point out the hi-low in case it wasn't noticed. These screws are great!

 

Thanks guys, you rock. Piggyback question:

Regular old #10 1/2" self tapping sheet metal screws should be fine to attach the 18g studs to each other and the track, correct?

Thanks again,
Brian

 

You can... I will typically use these.

https://www.homedepot.com/p/Phillips...05-0/203809493

 

The key with the durock is that the screw head set flush with the durock. I would still use the durock screws but would probably pilot dril some holes first so the screws would grab into the metal early without a lot of pre-spinning which could rout out the hole too much. Other types of screws will not grab the durock correctly and tapcons would have to be counter sunk which would be past the fiber mesh level and not have any strength in grabbing just the cement core of durock. Would recommend Hardie as that is solid core and you could countersink and still have sufficient grab

 

I think that in his last question he's asking about the screws to use for the steel stud framing only.

 

@xsleeper - Yeah i was... those #8's good for 18g? I was gonna go with #10's

@czizzi - Gotta use the cement board due to fireplace clearance issue. Plus I don't wanna hang veneer on Hardi. Am I missing something about the tapcons needing to be countersunk so much that they'll be worthless? They wouldn't have to go any deeper than the Rock-Ons... Plus I still gotta lathe and mortar over them anyway. Not sure I understand the concern...? On a side note, the tapcons would just be on part of the field. The edges of the durock will be secured to the metal studs.

 

If you breach the fiber mesh on durock you lose holding power. The newest Rock On screws have been redesigned with a torque head driver instead of a philips head or square bit. They also now look very much like tapcons as far as the thread pattern but are specifically designed for durock and to sink the heads flush. I used to hate these screws, just used the new ones on a bathroom remodel and love them. It is the right fastener for the job. I've seen floors put in using deck screws in durock and the heads pulled through and they had cracked tiles as a result.

I would just predrill and use the rock on screws, once they grab the metal, it should be good to go. There is not a cutting edged on the screws so that is why predrilling would give the screws something to grab on to.

 

He's asking about fastening the Durock to masonry. How would you handle that C ?

The flathead tapcons are what I've used with a slight countersink.

 

Yeah, what PJ said...
I'm using the Rock On's where the Durock meets steel, but part of the Durock needs to be fastened to masonry brick. Tapcons are the plan, I just won't countersink past the mesh if that's an issue.... Like I said, it'll be covered with lathe/thinset and stone veneer anyway. A little protrusion from the tapcons won't be a deal breaker. Other than that I can't think of any other methods to attach the Durock directly to brick? The top half of the fireplace front will be all Durock over steel, but the bottom half only the edges will be in steel, the field parts of the Durock have to be secured to brick. There's no clearance to put more steel between the Durock and the brick face.