Insulating concrete vs Homebrew Fireclay Mortar

[HConrad]

Hi. After my son and my 3rd summer of working on this, we finally finished the dome (whew!) and have laid the insulating blanket and started on the layer of insulating concrete to cover the blanket. My question is this (and I've looked all over the PDF plans as well as the forum for an answer); before I go out and purchase more materials for the homebrew mortar, is insulating concrete a different product?

Many thanks in advance for your feedback,

Heather

[Spinal]

Re: Insulating concrete vs Homebrew Fireclay Mortar

Insulating concrete, or more commonly called Vermicrete is a mix of vermiculite and cement. You can use perlite if you can't find vermiculite.

Ratio is 5:1 for the parts that need structural functions, all the way to 20:1 for the dome insulation.

M.

[HConrad]

Re: Insulating concrete vs Homebrew Fireclay Mortar

Fantastic! That will be so much easier. So, to confirm, 1 part of concrete to 20 parts vermiculite for covering the insulating blanket, then? Our plan was to finish with stucco or adobe.

Many thanks, H

[Laku]

Re: Insulating concrete vs Homebrew Fireclay Mortar

Fantastic! That will be so much easier. So, to confirm, 1 part of concrete to 20 parts vermiculite for covering the insulating blanket, then? Our plan was to finish with stucco or adobe.

Many thanks, H

No. 1 part of cement, not concrete.

[HConrad]

Re: Insulating concrete vs Homebrew Fireclay Mortar

Right! Sorry - I was on my way out the door and was not thinking clearly. Again, many thanks! H

[david s]

Re: Insulating concrete vs Homebrew Fireclay Mortar

If you use 20:1 you may have trouble with it not being firm enough. It only needs to be strong enough so that you can stucco against it. It will depend how thick you make the layer too. I find 10:1 works pretty well.

[HConrad]

Re: Insulating concrete vs Homebrew Fireclay Mortar

Thank you so very much! I really appreciate the feedback.

-H