Render/stucco dome a little help needed

[chidding]

Appreciate the help guys! this forum is the only reason i could do this project!

[eatingmorefood]

Howdy Mates : How do you make the final coating over the vermiculite to make it as waterproof as possible ? Were almost done, pictures here: DIY pizza, Pizza Making Supply, DIY Pizza oven, DIY pizza-ovens, DIY wood ovens, pizza Cutter, Pizza Stones, pizza knives, spice shakers, cheese shakers, crushed red pepper shaker, grill pizza, grill pizza, pizza Q, BBQ pizza, make pizza grill, makin Oven is built of mostly "FREE" recycled materials !
Cheers !

[david s]

Don't be in a rush to render over the vermicrete. If you calculate the volume of vermiculite used then you have added approximately a third of that volume in water. As you have made quite a rich mixture 8:1 verm. cement, then the mixture will not dry quickly because more of the spaces between the grains are filled with cement. Suggest you fire about 10 times before considering rendering over it otherwise you risk cracking the outer shell from steam expansion. Also suggest waiting until the outside render is complete and hard and again well fired before waterproofing. The render mix I use is 4:1:1 sharp sand, cement, lime.
Good luck.