Hearth insulation. Vermiculite v pumice

[kriso]

Hi there everyone, I have just found out about this site and have now decided to change my plans for a pizza oven to on of these ones. I have already built the base so now have to look at extra insulation in the hearth. In New Zealand fire bricks and vermiculite are pretty expensive $7 - $8 per brick and $10 for 5 litres of vermiculite. Has any one ever used pumice and concrete in the hearth instead of vermiculite? Would the thermal value be reduced too much?
Look forward hearing your thoughts.

Cheers
Kris

[dmun]

Pumice works, the ancient romans used it, it's way better than some of the workarounds like sand or broken glass. You may need more than the four inches you need for vermiculite or perlite.

8 dollars for a one dollar firebrick? What are they doing, shipping them by parcel post?

[Neil2]

Check for perlite. It does as well as vermiculite.

[spt]

Hi Kris

I am from New Zealand and also in the process of building an oven. I managed to pick up 100 litre bags a vermiculite from a garden supply off the internet for around $60.00 - do a search and find the cheapest. Also using fire bricks from placemakers for around $6 each after getting a discount for bulk purchase. Unfortunately we do seem to be paying way too much for bricks in New Zealand compared to others on this site.


Regards

Dave