insulation board over vermicrete

[mieno]

Hi
If I was to use insulation boards over the vermiculite concrete layer (to improve the insulation effect), do I need to glue or mortar the boards to the vermicrete? If so, what is the material to use?

Also, do you spread an underfloor paste of sand and fireclay over the boards if you are laying down a modular refractory concrete floor as opposed to a brick floor?

Thanks in advance.

[Ken524]

Originally Posted by mieno

Hi
If I was to use insulation boards over the vermiculite concrete layer (to improve the insulation effect), do I need to glue or mortar the boards to the vermicrete?

Easy answer: No. You are going to build a 1500 pound on top of the board. Gravity will win .

Also, do you spread an underfloor paste of sand and fireclay over the boards if you are laying down a modular refractory concrete floor as opposed to a brick floor?

I'll let someone else take that question.

[dmun]

Also, do you spread an underfloor paste of sand and fireclay over the boards if you are laying down a modular refractory concrete floor as opposed to a brick floor?

No. The fireclay/sand layer is for leveling the brick floor if you are laying it on an uneven surface, like vermiculite concrete.

[RCLake]

Not that this is a normal way to do it, I used regular mortar to install my insulation board over the concrete. I didn't feel it would move in the future but had a concern during construction, also my board came 12" x 12".
I used a wet fireclay/sand mixture to place my firebrick floor, but with our winter winds that dried our to fast. When I was mortaring down my first soldier row I didn't notice that I readjusted the floor slightly, so I have a couple of gaps I'll fill with with the dust from sanding the floor down. If I had to do it again I would use a little refractory mortar to place the floor.
for what it is worth