I am back on track with my wfo build. The base was built with concrete blocks filled with cement. My wife and I love an outdoor fire so where most people have a wood storage under the hearth I have a zero clearance insert originally intended for indoor residential use. It vents out the back into a stainless lines chimney.
My hearth is 4" thick concrete and rebar. Yesterday I poured my 5:1 vermiculite/concrete pad on top.
My question is should I use normal concrete to skim coat this? I have access to castable at 51/bag and flue set dry mix at 110/bag
These prices seem high to what some have been able to buy, medium density bricks are 1.66 a piece
My plan was to use the brick for the outer ring and then fill with sand and use the castable for the lid. If I were to go with a brick lid what is the best mortar to use out of what I can access.
Its covered right now to keep it out of the weather but I will load some pics when I open it up
Thanks for any advice
You don't need to skim coat the insulating concrete, unless you plan to stucco the whole slab and oven. What are you doing....enclosure or stucco on the dome?
As for casting the dome, it's been done...mass is mass for the most part. The trick is to cast, cure and dry it so that the material doesn't develop structural cracking.
If you build the dome with brick, 'best' depends on your circumstances, because the mortar is fairly forgiving. You can use a component mixture of sand,Portland,lime and fireclay for fire mortar or buy a refractory mortar ( though it tends to shrink in large joints) or you can pour castable into the voids after building the dome.