So it begins.. Pics+Questions

[chidding]

Hi all!

I finally have the frame completed and am hoping to start the pizza oven asap.

As I dont require a cement base I was planning to put sheet metal ontop of the metal frame and poor the vermiculite+cement mix. Am i correct in assuming this would be the correct method?

Also which vermiculite would i use. G2 or Fine Vermiculite, G3 or Medium Vermiculite,
G4 or Coarse Vermiculite.


The top of the pizza oven frame is 50x50 angle iron which is 1.3/1.5m so ill require 97.5 litres of mix.

I have been given 50x50 rebar mesh.. would this be required or have no real benefit?

Any help appreciated!

[dmun]

Insulating concrete has no tensile strength, no reinforcement is of any use. It has to be completely supported from the bottom.

[chidding]

Thanks Dmun,

Any thoughts on the vermiculite?

Cheers

[splatgirl]

I think I used the medium.
There's no reason you need to fill the entire base pan with vermicrete. It only needs to be UNDER your hearth/oven bricks. It would save you some mix and effort if you formed off an area just slightly larger than your oven footprint rather than the whole perimeter of the stand.

Putting rebar in the vermicrete isn't going to do anything except add weight.

I can't tell from your photo, but it looks like you just have "joists" in place to support the metal sheet of your base? I would add some perpendicular bracing, myself. Can't get that part too sturdy.

[splatgirl]

Now that I look at your photo again, I would DEFINITELY Add some joists sections that run perpendicular to what you've got. And I'd like to see the overall structure braced in the other direction, too. You've got the lateral covered with those diagonals, but that's only half the cube.
All of that said, I'm not a structural engineer so I'm just going with my gut, here.

p.s. Is your fence made of corten steel?

[chidding]

No idea on the fencing metal to be honest, all we call it is colourbond. COLORBOND® steel: Home

The base was designed to handle over 1000kg so im presuming this should be ok, it was designed by a structural engineer and welded by our lead fabricator (25years experience). So im hoping this would be ok..

Option 1.. really strong metal sheet with a 50mm vermicrete mix.. vermiculite is only $20 per 100L so this is a cheap option.

My option 2 is to do 25mm concrete reinforced with 50x50 rebar.. and then do 25mm vermicrete.. is this enough?

Option 3.. 50mm reinforced concrete with a form ontop made with vermicrete..

[splatgirl]

it seems like you are confusing the structural and insulation aspects--

The vermicrete layer is for insulation only. It has ZERO structural value. To have your oven work and retain heat properly, the vermicrete layer needs to be 4"/~100mm (unless you are using board insulation, in which case you don't need the vermicrete at all.)

As far as what holds that and everything else up, as long as it is utterly stable and can support the weight of your oven and whatever facade finishing you intend to do, concrete or steel sheet are both viable options.

IME, 25mm/1" of reinforced concrete would not ever be considered structural nor capable of load bearing (besides being difficult to impossible to fully embed the rebar and mesh in such a thin slab) To be such, it should be 4" thickness and reinforced with rebar and wire mesh. I guess it's possible your base was designed to allow for a thinner slab...run it by your structural engineer.

If you go with steel sheet, that would be taking the place of your reinforced concrete slab. From that point on, you would follow the pompeii plans to spec.
If you are going to go with a reinforced concrete slab instead of the steel sheet, you'd construct that according to the pompeii plans (or per your engineer) and then proceed as above with the vermiculite layer.

[dmun]

Any thoughts on the vermiculite?

There doesn't seem to be much practical difference in vermiculite particle size. Use whatever is convenient.

[chidding]

Thankyou so much for the help.. guess its back to the drawing board.

What i might do then is metal sheet at the bottom of the 50/50 angle iron with a 50mm concrete reinforced slab.
Once thats completed i will make a 100mm Form of vermicrete ontop of the slab.

Can you confirm this would work... considering i dont really have any other options..

again.. your help has been amazing.. very much appreciated.

Originally Posted by splatgirl

it seems like you are confusing the structural and insulation aspects--

The vermicrete layer is for insulation only. It has ZERO structural value. To have your oven work and retain heat properly, the vermicrete layer needs to be 4"/~100mm (unless you are using board insulation, in which case you don't need the vermicrete at all.)

As far as what holds that and everything else up, as long as it is utterly stable and can support the weight of your oven and whatever facade finishing you intend to do, concrete or steel sheet are both viable options.

IME, 25mm/1" of reinforced concrete would not ever be considered structural nor capable of load bearing (besides being difficult to impossible to fully embed the rebar and mesh in such a thin slab) To be such, it should be 4" thickness and reinforced with rebar and wire mesh. I guess it's possible your base was designed to allow for a thinner slab...run it by your structural engineer.

If you go with steel sheet, that would be taking the place of your reinforced concrete slab. From that point on, you would follow the pompeii plans to spec.
If you are going to go with a reinforced concrete slab instead of the steel sheet, you'd construct that according to the pompeii plans (or per your engineer) and then proceed as above with the vermiculite layer.

[splatgirl]

In this case, when you say "sheet metal" to me that means steel plate, aka something thick/rigid enough to do the job on it's own, no concrete needed. Pulling a guess out of my hat, I'd use 1/4" thickness or more. Measured by gauge, that would be about a 2.
But if by sheet metal, you mean something flexible or bendable (anywhere from about 14 gauge and higher), then you'll need the concrete, yes. In this case, the sheet metal is mostly just a pan to contain the concrete during the pour and contributes very little to the structural integrity. You could substitute a removable plywood form and achieve close to the same thing. But again, I am not in agreement with the idea of only a 50mm reinforced slab. Everything I've ever done with reinforced concrete and steel that is structural and load bearing has been 4"/100mm of material.

I would do either a 4" reinforced slab OR steel plate as the base. To do a little of both seems like twice the work to achieve a lesser result.