New Build to Fit Space

[JimboK23]

Hey Gurus,

I am looking at building an oven to fit a space where an old crappy gas BBQ was. I have drawn up some plans but was just wondering if anyone has experience with a tunnel shaped build like this and if i should do it or just bite the bullet and clear the space and start from scratch with a pompei.

So in the photos is the space where i want to build it, I will knock the back wall out and make a tunnel type oven as it's more rectangular than square. I have attached some 3D model photos as well of my plan. The Model is all 75mm fire bricks on a 50mm ceramic fibre board base. I will cover the dome in 50mm ceramic blanket then ~35mm vermicrete the outside of that and then ~15mm render finish. Would that be enough insulation to do longer cooks? Or will i need the whole half brick width to retain enough heat?

The other thing i am questioning in my design is the chimney placement, hopefully you can see in the 3D model screenshots then plan is to have it just inside the doorway slightly lower than the outside course of bricks.

Thanks for letting into the forum! Look forward to learning a lot!

[JRPizza]

Since I'm spending your money I would vote for starting from scratch
Seriously I am suggesting this for two reasons.
First ovens carry most of the weight around the perimeter, and most stands are sized so that the oven sits such that the weight is supported close to the block stand. It looks like if you build in that opening you would be putting quite a bit of load on those thin bricks and mortar joints and could very well have a failure. That floor is thin and does not look like it was designed to take bending stresses and vertical loads.
Second, when I built my stand it was, in terms of the entire process, a relatively small part of the overall time and cost. Starting from scratch will let you design the oven you WANT to build, not the one you have to fit in, and unless you are already a mason you will gain some skills and familiarity that will serve you well during the rest of the build. You will also hear from most here that the round Pompeii oven is structurally superior to a vault style oven, and possibly even easier to build.

[MarkJerling]

Why not just fill the space up and build a round oven on top? Barrel ovens are very different animals to round domed ovens.