Sand

[captbo]

Does any one line the bottom of the FB with sand? is it a good idea or not provided it is kept dry?

[Fishless Mickey]

What are you hoping to achieve by using the sand?

[The Czar]

Keep it dry from what?

[Rev.Mike]

i have seen a couple wood stoves that had a false bottom int them that was lined with sand, kind of acts as an insulation/ heat retainer, i think it would work, JM2C

[Rodcrafter]

I've seen people use it in their water pan instead of water. But not the FB.

[captbo]

In the ways I had seen it used I gather it was some kind of heat insulation

[Gizmo]

I think if you check (laser) all 6 walls of any FB you'll discover the least amount of heat collects on the floor. Any attempt to insulate the floor will only effect a very small percentage of the FB total heat loss. Sand is cheap but the labor to maintain it isn't …. fire brick would do the same thing but it's much easier to work with.
imho

[captbo]

Got ya Gizmo. so if one was to design a FB to be about the 106% of the CC calculation one would take a 1" fire brink and allow for the space it occupies on the fb to get it right

[Gizmo]

I wouldn't add to the FB size to fit the fire brick into place. Once the fire brick get hot they will contribute heat stabilization to the overall cubic inches of the FB so changing the FB size would not be necessary. Just make sure your basket/ash pan etc will clear.