Durock users...

[trailblaze]

yeah it's me again.. haha

on to the Durock cutting/layering/ thin setting etc.

1st question... one side says mortar other side Masic? whats Masic, and if i was going 3 layers, should they all be the same side up?

2nd question.... I plan on thin-setting the bottom to the middle layer and then the middle to the top...also screwing the sheets together using Durock screws.... since i'm thin-setting them too how many screws do i need to use, like one every 6" or 12"

3rd...when screwing them, should i drill out a pilot hole a tad smaller than the screw?

4th and last question... do i need to worry about expansion and contraction with temp changes?? i screwed the 2x4s down like crazy then screwed the plywood to them like crazy if that makes a difference

 

[fossil]

I've put down a boatload of Durock, and I've never seen where the two sides were labelled anything, or appeared differently. Maybe they've changed the product since I last worked with it. Dunno what "masic" is...could the word be "mastic"? I really don't think I'd worry about it all that much, they're just slabs of cement going down horizontally. Maybe a grid of screws about 8" on center. Genuine Durock screws are self tapping/threading, no need for pilot holes, in fact you'd likely defeat the design of the Durock screws. Rick

EDIT: Durock will not absorb moisture, thus no appreciable expansion/contraction.

 

[axlerosewood]

1 rough side out for tile thinset to adhere to. Mastic is adhesive or glue.
2 every 4" or more the better
3 no
4 no worries lots of screws

All the best

 

[trailblaze]

yeah it was mastic... kinda scewed up with the way it looks painted on the board...

ok, i'll scew each layer to the one below it pretty good.. and my screws are made by Buildex "Rock-On" #9 hi-lo thread for Durock or Wonderboard...

glad to know it won't expand or contract... i kinda figured the Durock wouldn't, but maybe the base layer or plywood

 

[trailblaze]

I've put down a boatload of Durock, and I've never seen where the two sides were labelled anything, or appeared differently. Maybe they've changed the product since I last worked with it.

yeah, the rougher side has the writing on it and is the "mortar" side...the other side is smooth and no writing

 

[BJ64]

According to the book from Black and Decker called "The Complete Guide to Decorating With Ceramic Tile", it does not have a thing about multi layers of Durock. I will venture a guess that you are creating something similar to the thicker cement board. With cement board the book says put screws every 6 inches along the sides and 8 inches apart in the inside. Drive screws 1/2" from the edges to prevent crumbling.

Mastic is a type of glue for installing small tile. It is good for wall tiles smaller than 6x6 and is not good for floor tile (from that book).

As for pre-drilling the holes, I could not find any thing.

As for expansion, leave a 1/8 inch gap between sheets of cement board. Tape joints with alkali resistant fiberglass mesh and mud together with thinset.

That is the best I can find from that book. Hopefully somebody that has actually done this will add in to this.

 

[fossil]

Those screws'll work just fine...no pilot holes. Since you're spreading thinset with a serrated trowel between all layers of your sandwich, it hardly matters which side is which...I don't think it really matters anyway. (Personally, after two entire bathroom/shower installations, and I forget how many square feet of countertops, I don't care if I never see another piece of Durock in my life %-P ). Have fun! Rick

 

[BJ64]

Those screws'll work just fine...no pilot holes. Since you're spreading thinset with a serrated trowel between all layers of your sandwich, it hardly matters which side is which...I don't think it really matters anyway. (Personally, after two entire bathroom/shower installations, and I forget how many square feet of countertops, I don't care if I never see another piece of Durock in my life %-P ). Have fun! Rick

That is cool. By the time I got done looking that stuff up you guys had the issue plastered!l

 

[axlerosewood]

Being a tile guy... use lots of screws. 1/4" trowel for the thinset and screw every 4". We just use drywall screws. What you are doing is laminating like wood. The screws are the vise to laminate it untill the mortar dries.

Make sure its not the cement board with styrofoam balls in it. Very stinky when heated up!

 

[trailblaze]

well, thanks again for all the info... this site is one of best forums i've joined! you guys are very helpful and you don't get all smart-assy with answers to what are probably stupid questions...

well i just cut all 3 layers, didn't leave any space at all between joint... and didn't plan on using joint tape... hmmm

i'll follow the screwing guidlines.. who would have thought by this time in my life i'd be asking how to screw something..

 

[04074]

Durock recommends 1/8" between panels: (broken link removed to http://www.usg.com/USG_Marketing_Content/usg.com/web_files/Documents/Installation_and_Appl_Guides/DrckCement_Board-Installation_Guide.pdf)

 

[trailblaze]

Durock recommends 1/8" between panels: (broken link removed to http://www.usg.com/USG_Marketing_Content/usg.com/web_files/Documents/Installation_and_Appl_Guides/DrckCement_Board-Installation_Guide.pdf)

well i guess i could get an angle grinder and take a tad off... but then from what i read, u fill the joint back up with mortar, then tape it and level it.... for my application... being level isn't "much" of a concern... the top rock isn't ever going to be completly level

i did learn from reading that to thin-set it to the plywood... which i didn't think needed done!!

 

[firefighterjake]

Durock recommends 1/8" between panels: (broken link removed to http://www.usg.com/USG_Marketing_Content/usg.com/web_files/Documents/Installation_and_Appl_Guides/DrckCement_Board-Installation_Guide.pdf)

Oops. Guess I have to tear my hearth all apart now.

Actually, this thread is as good a place as any to thank anyone and everyone who has ever posted any information on how to build a hearth (and especially the person who did the wiki article on hearth building). I don't have pictures yet (waiting until I get the stove in, trim up and get the wall painted), but I have to say thanks in no small part to the folks here I'm really pleased with my slate hearth . . . especially considering the fact that this was my first ever "tiling" job.

 

[pumiglk]

I believe the tape and fill between the cement board sections is to fill the voids and prevent deflection and ultimately cracked tiles. Not filling seams may also create voids for grout to retract into and give uneven grout or bubbles. Don't know if with the size of the rocks you were laying down these would be significant issues. Doesn't take long to skim coat the screws and fill the seam voids though so proabably better safe than sorry.

 

[trailblaze]

I believe the tape and fill between the cement board sections is to fill the voids and prevent deflection and ultimately cracked tiles. Not filling seams may also create voids for grout to retract into and give uneven grout or bubbles. Don't know if with the size of the rocks you were laying down these would be significant issues. Doesn't take long to skim coat the screws and fill the seam voids though so proabably better safe than sorry.

my work-in-progress thread shows the size rock i'll be using... i am really thinking it's not going to matter... i'll be putting about 1/2"-1" of mortar on top of the final layer of Durock, and my top finish rock is tough to break with a 8lb sledge soo cracking shouldn't be likely

 

[pumiglk]

yeah, that was my impression - they look plenty sturdy