Extended Hearth Construction Question with regard to proper method to "sandwich" Micore and Durok la

[njkev]

Hi,
I have constructed the rough framework for a 24" x 72" extended hearth in front of my fireplace out of 2"x6" lumber, with studs every 8", and 3/4" plywood over the framework. I have enough 1/2" Micore 300 (mineral fiber board)and 1/2" Durok (cement board) to allow for two layers of each material for my extended hearth. I require a total of 1" of Micore to meet the manufacturer's (RIDICULOUS) requirement of K-Value=0.43. The Durok is required ONLY as a rigid base for the tile.

Please keep in mind that my questions below are regarding structure rigidity requirements for the tile, NOT floor protection:

1) Is it better put the FULL 1" (two 1/2" layers) of Micore on the plywood together, and then the Durok over it, OR, is it better to alternate....1 sheet Micore...1 sheet Durok...I sheet Micore....1 sheet Durok?

2) If the FULL 1" Micore option is OK, should I use TWO 1/2" sheets of Durok as opposed to only ONE, or is it just overkill at that point?

Any constructive criticism and/or advice is greatly appreciated! If you have a BETTER option for me than the two I have proposed, please do tell me!

Thanks,
Kevin

 

[njkev]

ANYONE reading this have ANY opinion??????

 

[Jags]

Option 2 and use both sheets of Durock. The extra sheet will give you extra stiffness for the long haul.

 

[fossil]

^ What he said. Rick

 

[njkev]

Option 2 and use both sheets of Durock. The extra sheet will give you extra stiffness for the long haul.

Option 2, meaning alternating the materials......Micore...Durok....Microre...and Durok?
Thanks,
kev

 

[Jags]

Option 2 and use both sheets of Durock. The extra sheet will give you extra stiffness for the long haul.

Option 2, meaning alternating the materials......Micore...Durok....Microre...and Durok?
Thanks,
kev

No, I don't think I would alternate the materials. On the other hand I don't think there is anything to gain or loose by doing it.

 

[njkev]

Option 2 and use both sheets of Durock. The extra sheet will give you extra stiffness for the long haul.

Option 2, meaning alternating the materials......Micore...Durok....Microre...and Durok?
Thanks,
kev

No, I don't think I would alternate the materials. On the other hand I don't think there is anything to gain or loose by doing it.

ok...thanks for your advice Jags. Ignore the PM I just sent though... I just thought it MIGHT be more structurally sound alternating the material. No really sure.
kev

 

[Jags]

Durock does have the ability to flex or even sag with long term weight on it. I have even seen it "dent". With the solid structure of your frame, then plywood, you have eliminated most of this. So now its just getting your "R" or "K" value and providing a substrate for your tiles.

No real tricks to it. Slap it down, secure it and get to tile'in.

 

[njkev]

Durock does have the ability to flex or even sag with long term weight on it. I have even seen it "dent". With the solid structure of your frame, then plywood, you have eliminated most of this. So now its just getting your "R" or "K" value and providing a substrate for your tiles.

No real tricks to it. Slap it down, secure it and get to tile'in.

Jags,
Thanks again for your help! I'll post photos for before and after I tile it. BTW....what distance should I space the screws from one another? And should I screw each layer separately?
Thanks,
kev

 

[Jags]

Durock does have the ability to flex or even sag with long term weight on it. I have even seen it "dent". With the solid structure of your frame, then plywood, you have eliminated most of this. So now its just getting your "R" or "K" value and providing a substrate for your tiles.

No real tricks to it. Slap it down, secure it and get to tile'in.

Jags,
Thanks again for your help! I'll post photos for before and after I tile it. BTW....what distance should I space the screws from one another? And should I screw each layer separately?
Thanks,
kev

~12" should be plenty of overkill. No real need to screw each layer down unless your screws aren't long enough to hit the wood underneath.