Osburn 1800i "non-combustibe" hearth - no R value given

[par38lamp]

I have pretty much decided on a Osburn 1800i insert, and was reading the manual cover to cover today. It talks of hearth protection - 16" if unit is less than 4" from the floor, and 6" if it's 4" or above, plus 10" of spark protection.

Nowhere that I could find in the manual or website did it give the R value of the "non-combustible" hearth needed.

Thoughts?

 

[MountainStoveGuy]

then r value doenst matter, it just has to be non combustable.

 

[elkimmeg]

this is an interesting subject one that should be reconised and better explained I have to dig into codes but I do remember reading height requirements and reduction of r-
values. air space does have an r-value of .97 per inch That is why I also have pushed for damper block off plates a good seal creates a dead air space in that chimney cavity