Newbie Hearth Insulation Question

[seventiesboy]

Hi
Just joined today after lurking for a while. We started our pizza oven project a few weeks ago and are getting to the stage of heart insulation and hearth laying.
We have built the brick and concrete base for the oven so far.
We are trying to keep to a budget and use recycled materials as much as possible.
The question is therefore when mixing the vermiculite/portland cement for the hearth insulation base could you add broken glass as ballast therefore reducing the amount of vermiculite needed.
This would keep the cost down but would the insulation still be good enough?
Thanks guys in anticipation.
SB

[texman]

Re: Newbie Hearth Insulation Question

70
Not sure if you have proceeded or not. I wouldnt use glass in the insulation. Vermiculite and portland are fairly inexpensive. Glass wont insulate either.
Tex

[seventiesboy]

Re: Newbie Hearth Insulation Question

Thanks for that.
Yes we have progressed and went with the standard vermiculite/portland mix for the hearth pad. This is drying nicely now and hope to crack on with the firebrick hearth tomorrow.
Didn't want to mess it up so thought it was best not to mess with standard thinking.
Thanks for the reply.