Pizza oven insulation, is there a substite for perlite, vermiculite and fiber glass wool?

Hello there! I'm making plans to build a medium/small brick pizza oven, maybe the inner diameter of the dome little bit bigger than the diameter of a yoga ball. i live in venezuela so it's really hard for me to find perlite, vermiculite, or fiber glass wool for the insulation layer, can i use a mixture of sawdust and cement or something like that for the outside layer? Or what could i use in wich proportions?

Or is it even a need for that kind of insulation in the oven i want to build? I would be using it to bake pizzas like once a week, for myself, or for no more than 6 people. It wouldn't be fine just the brick layer with an extra layer of concrete?

Rice hulls are considered to be an excellent insulator.
When combined with cob or refractory cement,  they burn out where the material gets hot enough and leave a void behind.
Where the heat is lower,  they still provide insulation.

Sawdust should work the same way, but less effectively.

Can you get the expanded clay balls, the ones used in houseplants? they insulate as well.

Otherwise there are ovens without insulation on top, however concrete may crack

Lava stone, light straw clay, mineral wool are all options. Just remember that you want quite a thick thermal mass layer inside the oven before you add the insulation. Bricks, then a few inches of cob, then insulation. Then an outer shell.

Luis Molero wrote:
Or is it even a need for that kind of insulation in the oven i want to build? I would be using it to bake pizzas like once a week, for myself, or for no more than 6 people. It wouldn't be fine just the brick layer with an extra layer of concrete?

I agree with what everyone else has said.  In your case I'd look for straw or rice hulls mixed into cob, which as William said will burn out and leave voids.

But I want to come back to that question you asked.  Yes, you absolutely need to insulate your brick oven.  If you make it properly the top of the oven reaches 1,000 degrees F.  If you do not insulate the oven, two things are going to happen:

1) The heat inside the oven is going to bleed off, and you're going to get poor quality pizzas.  You'll need more wood, more time, and get disappointing results.

2) Anyone who touches the oven is going to get a serious burn.

Brick with an extra layer of concrete does not count as insulation by the way.  It just won't work the way you think it will.

Thank you all for the help!! I might be able to find the fiber glass P.s: i'm new to the forum and i don't know how to make quotes, sorry...

Hi Luis,  Quoting someone is easy. Just click the "quote" button above the persons comment you want to quote and a new window should open up with all their comments in between some computer code to identify it as being a quote. If you only want to quote a small portion of what they said, then just delete the part that you don't want....just make sure that you don't delete the
"" before or after and you should be good to go. Also, if you want to make sure you got it right before posting, just click on the "preview" button at the bottom of the message window.
Hope this helps.

Luis Molero wrote:Thank you all for the help!! I might be able to find the fiber glass P.s: i'm new to the forum and i don't know how to make quotes, sorry...

That's a good start but remember that you're trying to insulate something that is ten times hotter than your typical attic.  Be sure to use a lot.