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Portland cement to perlite ratio

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  • Portland cement to perlite ratio

    For under the oven floor: I've seen on here a 3 Perlite :1 Portland ratio and a 10:1 mixture. Which is best for under my fire bricks of the floor? Why so???
    What comes easy won't last long, and what lasts long won't be easy.

  • #2
    The more cement in the brew the stronger it will be, but it also reduces the insulation value. A 5:1 is strong enough for the under floor application and still provides adequate insulation. Over the dome does not require much strength so is better made far leaner. A 10:1 brew is about as lean as I can go, but still being reasonably workable and strong enough for a decent substrate to stucco/render against. (See table)

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    Kindled with zeal and fired with passion.