Cost effective alternatives to ceramic insulation

[yoboseyo]

I find ceramic insulation to be prohibitively expensive. It's either just where I am or I'm underestimating it's cost. The price for a layer of 1" thick material is reasonable, but when you get to the recommended 3-4", for both dome and hearth insulation, I'm looking at upwards of $500 for insulation materials alone. And I don't want to skimp on "good" insulation, noting that the thickness of vermiculite to achieve similar thermal conductivity is both space-limiting and unsightly.

So what I was thinking, is that the major advantage of ceramic insulation is its high temperature tolerance, right? Surely after the first inch, you can use forms of insulation with similar thermal conductivities but lower temperature rating, right? The cost of insulation can be halved if I can find cheaper material for 2/3 of it.

Thoughts? Recommendations?

[Gulf]

Hi Yoboseyo,

Welcome to the forum. Imo, you are correct in your reasoning. Ceramic fiber is an excellent choice for the first 1" layer as long as it is fitted neatly. You did not mention whether or not that you are building an igloo or an enclosure? My advice may change and will depend on your choice.

[yoboseyo]

Hi, I'm planning on building an igloo

[Gulf]

Okay. 1" of ceramic fiber blanket will work fine as an insulation as well as an expansion joint between the dome and a vermictete or perlcrete layer (10 to 1). Also, ceramic fiber board will work well on top of the same at a (5 to 1) mix.

[yoboseyo]

I read that some people recommend 3" of ceramic insulation for optimum performance, both around the dome and under the hearth. You recommend just 1" and then vermicrete/perlcrete? Vermicrete/perlcrete is a less effective insulator. I was thinking of something with similar insulation like Rockwool.

[david s]

I tried rockwool for a couple of ovens to save some cost, but found it difficult to work against because it’s springier and tends to compress the money saved was little compensation for the extra difficulty and labour increase, so I quickly went back to ceramic fibre blanket and 10:1 vermicrete.

[Gulf]

I read that some people recommend 3" of ceramic insulation for optimum performance, both around the dome and under the hearth. You recommend just 1" and then vermicrete/perlcrete? Vermicrete/perlcrete is a less effective insulator. I was thinking of something with similar insulation like Rockwool.

david s has addressed the use of rockwool blanket over the dome. I can't confirm the compression strength of all rockwool board insulations. 2" of ceramic fiber board is about equal to 4" of V/Pcrete (5 to 1) which both should have the compression strength that you need to hold up the dome weight. 1" of ceramic fiber board placed on top of 3-4" v/pcrete should reach the "optimum" that you are looking for.

Three things that you should also note:
1. Not all insulation boards that are sold have the compression strength needed for a wfo dome. That includes ceramic fiber board and rockwool. You must get the material data sheet from the provider to confirm that.
2. V/Pcrete works very well as long as it is allowed to dry and stay dry. Elevation and drainage shoul be a major concern with any under floor insulation.
3. Calcuim silicate board has about the same insulation factor as ceramic fiber board and may be cheaper to source for under the dome insulation.

[rajhlinux]

I find ceramic insulation to be prohibitively expensive. It's either just where I am or I'm underestimating it's cost. The price for a layer of 1" thick material is reasonable, but when you get to the recommended 3-4", for both dome and hearth insulation, I'm looking at upwards of $500 for insulation materials alone. And I don't want to skimp on "good" insulation, noting that the thickness of vermiculite to achieve similar thermal conductivity is both space-limiting and unsightly.

So what I was thinking, is that the major advantage of ceramic insulation is its high temperature tolerance, right? Surely after the first inch, you can use forms of insulation with similar thermal conductivities but lower temperature rating, right? The cost of insulation can be halved if I can find cheaper material for 2/3 of it.

Thoughts? Recommendations?

Whats crazy is that ceramic blanket is cheaper than ceramic fiber boards. Was wondering if anyone here used ceramic fiber blanket is insulation for the base foundation.

[Gulf]

The blanket is soft and pliable. It will compress under the weight of the dome walls. That will reduce it’s insulative quality and leave a bulging floor where there is not as much weight.