Is it okay to cut the stove boards from tractor supply/Lowes?

So after doing some research here I am pretty sure that against my father-in-law's insistance, my 3-4 inch thick stone hearth over framing is not gonna cut it for the 1.5 r-value needed for the NC-30, except where the old millboard is at(too far right of where I would like the new one), I'm considering a piece of stove board. Wanted to know if it is possible to cut the imperial brand type 2(I can only find instructions for their type 1 online)? I am sure that this will void the warranty but do you guys think it would affect the actual thermal protection(other than the smaller area)? Don't really wanna do a raised platform if I can get around it.

Well, after some careful thought I think I've decided to build a raised platform from 2 1/2" metal studs on at least 8(probably 7)" centers, with two layers of 1/2" durock and tile over it. The reason I was looking to find something I could cut was because the stone hearth(I'll try to snap a pic soon) is 42" x 12ft. long, with same stone behind as an entire wall. It's already raised about 8 inches from the rest of the floor(built on 2x4's, then ply, then the stones). I'm gonna make a removable extension out of similar material to get the 52" in front of the door I need.
This was never a problem because the two previous stoves on the hearth were side loader circulators and there was old school(asbestos) millboard underneath the 3" thick stone. I don't know if either of the old units needed a high R-value underneath them or if my father in law thought the stone would insulate good enough but I have since learned here that that stone provides virtually no R-value..

All in all, a lot of extra work, but I'de rather do it right vs. burning down the house(although on second thought... ).

bobdog2o02 said:

Not even remotely funny.

https://www.hearth.com/talk/threads/boom-house-burned-down.128097/#post-1725432

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Didn't mean to offend bobdog.. A fire is nothing to scoff at. I have known several people who have had their homes burned to the ground(one girl I went to school with that this happen TWICE!). I was just making a small jest at the state of my 1860's farmhouse, where my frustrations come to fruition when I run into the issue mating modern day construction materials to an old farmhouse where "straight and level" and "on center" didn't seem to matter to the original builders..

begreen said:

Can you post a picture of the full hearth that illustrates the issue? I'm not following why the board needs to be cut.

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Here is a (bad) pic of "the stone wall" as we call it for obvious reasons. Ignore the clutter; we just got new furniture and had to get the excercise stuff off the carpet to clean.

ddahlgren said:

Thinking outside of the box what about some sort of wrought iron platform under the stove with enough air space so easy to clean under it?

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ddahgren,
That would def. Look pretty cool but I think it would get a lot more pricey than I wanna do to make it weight bearing enough.