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Insulation question regarding compression strength

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  • Insulation question regarding compression strength

    I'm soon pouring the base so I’m planning ahead and sourcing materials for the rest of the build. On the insulation below dome, I have a question about compression strength.

    I have found this calcium silicate board multipor:
    It has a compression strength (compressive resistance) ranging from 200 kPa to 350 kPa. I could compress the material with my fingers easily!
    From my calculations my dome’s footprint will be about 0.2 kg/cm2 (90 cm diameter) and 200 kPa equals 2 kg/cm2. So I should be on the safe side with a factor 10??

    What is the consensus on minimum strength required from insulation boards?

  • #2
    75 psi or about 517 kPa at 5% compression
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    • #3
      Click image for larger version

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ID:	421972 Given that a 10:1 vermicrete is considered inadequate and a 5:1 about right then the min would be around 150 psi.

      Last edited by david s; 05-02-2020, 04:35 PM.
      Kindled with zeal and fired with passion.


      • #4
        I found another calcium silicate board, skamowall, with 2800 kPa, about 406 psi. It has similar insulating properties. That should be a better solution then.

        Here a picture of my progress so far. Getting ready to pour foundation today.