Raised Hearth Construction Question - URGENT Help Requested

[Detector$]

We are building a new house and our builder is just about ready to get started on our hearth for our woodstove.

The stove is heavy (465 lbs) and requires a minimum R-Value of 1. We are good on the size requirements, but unsure of the construction methods and materials.
We will be starting on top of our OSB sub-floor, and were thinking of using 2x4 metal studs for air-space, then a layer or two of durock, and the top layer of brick or Owens Corning Hearthstones.

I have heard you guys talk about putting a layer of sheet metal down before and/or between the durock... why? To keep the stove legs from busting through the durock?

Is the layer of latex-fortified portland cement also required between the layers?

Will the durock support the weight of the stove and the pressure from the stove legs with the studs placed on 16" centers?

THANKS!

 

[fossil]

The only thing that's gonna keep the stove legs from busting through the Durock is to have at least a well-supported nice flat sheet of 3/4" plywood or OSB subfloor underneath the Durock. You can't put a sheet or two of Durock up on metal studs and set a stove atop. Durock is not a structural flooring material. The reason you've read about sandwiching sheet metal into a hearth is for the added insulative properties afforded, nothing to do with structural integrity. What kind of stove is it? How high would you like the hearth to be raised? I'll attach a pic of what we did...masonry over 3/4" subfloor, to raise the stove 12" because I hate bending over. Just a thought. Rick

 

[EatenByLimestone]

Feel free not to place a dead cat infront of the stove. It creeps some of the houseguests out. :lol:

Any reason why you are building it raised? An r value of 1 isn't too much and shouldn't require it to be raised any noticeable amount off the floor.

Matt

 

[EatenByLimestone]

Here is a list of common hearth r values.

(broken link removed to http://chimneysweeponline.com/horvalue.htm)

MAtt

 

[fossil]

I put my dead cat in all my pictures...it's kind of my artistic signature. Besides, I really miss him. Or at least I did until he started to smell real bad. :down: Rick

 

[Elfin]

Ha ha ha on the dead cat! I hope I look that content when I'm dead!

Fossil pretty much said it all, but one thing to add... for structural integrity, simply make sure your studs line up with the footprint of the stove. Add that structural layer of plywood and your structure will be plenty strong enough... what you add after that is for R-value alone and your substrate for your brick or hearthstones.