2024 Neapolitan oven build

[daidensacha]

I used to do two 35mm layers of vermicrete with a week of drying between layers ( a thicker layer does not allow moisture deeper in to dry fast enough).

A handful of powdered clay for every litre of GP cement imparts more stickiness to help application.

For this interested here's my 10:1 recipe:
By volume;
5 parts medium grade perlite
5 parts fine grade vermiculite
1 part GP cement (+ a little powdered clay)
4 parts water

Mix dry ingredients then add water slowly folding in as you go (best done in a barrow)
If water pools in the bottom add a little more dry material. Too much water will wash the cement off the grains of perlite and vermiculite.

Good info David, thanks.

This is timely and really helpful for me. I’m in the final stages of planning for my own build, and working through details.

In Germany the grading of Perlite and Vermiculite is mostly in a range of millimetres.

From googling I read fine grade vermiculite equates to 1-3mm, and I have found 2-3mm Vermiculite here.

With regards to fine medium grade Perlite, I was looking at 2-6mm.

Would this be close to grades you mentioned?

[david s]

Yes. I’ve also found that the finer the grade the more water that is required in the mix. The drawback with this is that water turning to steam suddenly is your enemy, but allowing sun and wind do the job for you, while it works well, just slows down the build time.