Questions regarding base/foundation

[GJC]

Hi!

I'm definitely new to this. I came late to the forno bravo forum after starting my build and am amazed at the amount of information on here. I had very little experience with masonry when I started my project and have learned a ton so far. Definitely learning as I'm going, but I think the winging it aspect is going to come to a hault as I start building the dome. Reading about other people's builds and the complexity of cuts and angles I think will require a lot more planning.

Here's where I'm at...

I started with a cinderblock base with rebar and cement in the holes and faced it all with brick. I then poured a 4" cement top and then a 4:1 vermiculite/portland cement 3" layer for insulation. My question is....Am I ok to use the vermiculite layer as my foundation under my dome? Do I need to pour another smooth layer of cement on top of the vermiculite? I was going to put a layer of sand under my bricks to level everything out and then get going on my first course on top of the vermiculite, but I figured I'd ask before going any further.

Any recommendations would be appreciated. I attached a couple pictures too, so please let me know if anything problematic stands out.

Thanks,
Greg

[UtahBeehiver]

It is good you are at least asking before you reach the point of no return. 3" of 4 to 1 vcrete is a little light in terms of thickness and K value. 5 to 1 is structurally good enough for under an oven with 8 to 10 to 1 over the dome for insulation. If you can another 2" of 5 to 1 vcrete would be better. No to concrete, it would act as a heat sink. On another note, is there a particular reason you are going with full soldiers on the first course. This set up may require buttressing of the walls due to the natural outward pressure from the dome at the meeting of the dome and the top of the soldier. You would be better with 1/2 height soldier or a 1/2 headers. Leveling the floor, use a 50/50 slurry of fire clay and sand, installed with a 1/2" notched trowel (like you are laying ceramic tile) if your second vcrete layer is not level. I cannot see how much side room you have but you will need to factor in insulation thickness and final coating thickness as well.

[GJC]

Awesome! Thank you so much!

I'll put another couple inches on it this weekend!

As for the full length bricks, I’ll definitely take your advice and do half bricks. There a preferred method soldier vs sailor?

I left 6” around the outer perimeter for insulation and finish coat. Should I bump it up?

Cheers! Thanks for your input!

[UtahBeehiver]

Half soldier or half "header" not "sailor" will work (builder choice). 6" around perimeter should be fine even if using vcete (8 or 10 to 1) 4 to 5" thick. If you are using ceramic blanket (min 2") even better..

[GJC]

Great! Thank you! Poured another layer of 5:1 vermiculite Portland last weekend. Was hoping to start laying down the slurry sand clay mix this weekend and start laying down the floor. Is there a good brand of fire clay at a hardware store that I should look for? Is that the same as refractory cement? Any info on what to get would be appreciated! Thank you!

[UtahBeehiver]

hc muddox is a calf. brand of fireclay

[GJC]

Thanks Utah!

I've read a little about putting in weeping holes at this stage? Can someone please explain what those are and how they work? I'm guessing as the oven gets hot, moisture gets released from the dome etc? Why is it important to put the holes and are the specifics on how you want to install them?

Sorry for the ignorance. Just looking to learn!

Thank you!
Greg

[Chach]

Thanks Utah!

I've read a little about putting in weeping holes at this stage? Can someone please explain what those are and how they work? I'm guessing as the oven gets hot, moisture gets released from the dome etc? Why is it important to put the holes and are the specifics on how you want to install them?

Sorry for the ignorance. Just looking to learn!

Thank you!
Greg

those are put there to drain any water that may enter and get under the oven. wet insulation under the cooking floor creates poor performance of the oven. Some builders put weep holes in others raise the insulating layer if using a board type insulation by using ceramic tile or pavers first and then insulating board. some also do the raising and weep holes. Usually builders who use Vermacrete usually install weep holes. my oven is in an enclosure I did not install weep holes as it should be water proof but still you never know but I did use foamglas first which is a waterproof glass cellular insulation then 2" of thermogold 12. im not to concerns about water infiltration but you never can be to careful. now that I think about it I probably should have installed weep holes as it would not of hurt anything you just have to make sure you put some kind of screening in so bugs don't climb up through the hole.


Ricky

[GJC]

Thanks Ricky!

[GJC]

Hey there...

so a year later and I’m done with the brick dome and going to start the outer insulation. My domes not perfect by any means. I’m not a mason and this was my first time doing anything with brick.

But my question is this.... I was just planning on doing another layer of vermiculite/Portland mix around the oven. Should I do a ceramic blanket or would a 4-6” layer of vermiculite be sufficient?

Thanks for the input!

Greg

[UtahBeehiver]

Looks like you have limited space between parilla and oven. 2" of ceramic fiber with a stucco coat may be you best bet with the limited space you have.

[GJC]

Thank you!