adobe+vermiculita insulation Other Oven Types Discuss adobe+vermiculita insulation in the Pizza Oven Design and Installation forums; Where are you finding the thermal conductivity values?...

[papavino]

Where are you finding the thermal conductivity values?

[kebwi]

Oh, I don't even remember. Most of the websites for the *manufacturers* of these materials (not necessarily the suppliers, who seem borderline clueless in some cases) either have data specs posted online or PDFs you can download. I honestly don't have them bookmarked, I've been skimming and skipping mostly.

[JoeyVelderrain]

Originally Posted by papavino

8# blanket is going to insulate better than 6# and 4#. The higher the density of fibers, the more little air pockets and tortuous the air path will be. It holds the heat back more efficiently than a less dense mesh of fibers.

yeah, this makes total sense to me.
thanks!

[voon]

When you say it works fine, dmun, do you mean that if you use the described method (drill mix, then add vermiculite last) then up to 10:1 can replace the standard 5:1 even for structural support, like the hearth...or would you not recommend going over 5:1 for the hearth and only using higher ratios for the dome?

I'm a new member, and no expert on oven building or masonry, but my understanding from reading the free Pompeii oven plans on this site is that vermiculite or perlite are not added to the concrete that forms the structural support for your oven. You make a form on top of your stand and pour normal concrete with 1/2 inch rebar inside for the structural support layer. The insulating layer can be FB board or vermiculite/perlite cement mix that is poured on top of the structural layer. Then you build the floor and dome on top of that.

Again, I'm no authority, but I don't believe that a vermiculite or perlite cement mix is ever intended to be "structural", especially underneath the oven. It's for insulation.

[dmun]

Again, I'm no authority, but I don't believe that a vermiculite or perlite cement mix is ever intended to be "structural", especially underneath the oven. It's for insulation.

This is exactly right. Insulation layers have high compressive strength, which means you can pile a lot of weight on top of them without their squishing, but no tensile strength which means you need to support this layer from below.