wood stove floor protector- use air entrained concrete?

[davefitz]

The manufacturer of a wood stove has specified that the overall R value for the floor protector be greater than or equal to 2.06 (ft2 F hr/btu). The generally listed value of R for air entrained concrete is R=3.9 per inch of thickness, implying a minimum thickness of 0.528" if air entrained concrete is used.

The question then becomes: Is there a certified test on file that demonstrates this R value, so that I can satisfy the building inspector? I have so far been unable to find a listed value for R for commericially sold air entrained concrete ( sakrete, quikkrete) .

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[cranky108]

Try cement board. I have used it below tile, because it is one piece, and can block an ember.

 

[Compositepro]

An air gap under the thermal protection is more effective than anything else. A required R-value for the thermal protection assumes a certain R-value for the floor itself. So, cement board with with spacers underneath every 6".