Should the first two rows be mortared in barrel vault design?

[Digga Don]

First time builder of barrell vault design based on Forno bravo. Have read posts reccomending the first two rows of fire bricks in main chamber be dry stacked. What is the reason for this? A commercial retailer told me to mortar everything. Confused Digga Don Tassie

[Steady]

Hi Digga Don, I have no knowledge to answer your question - just posting to welcome you as a fellow Tassie member

[Digga Don]

Thanks Steady. Building at a shack in central highlands so want to get it right as external temperatures will be high and low over the life of oven.

[Digga Don]

Also walls of vault main chamber will be brick bond pattern. should this extend inti the back wall or just finish flush and mortat joint

[UtahBeehiver]

I suggest you look at Karangi Dude's thread, he recently did a new hybrid barrel design and from Aussie land. Also I believe Tscar did a nice barrel as well.

[Steady]

He does some wonderful work

https://community.fornobravo.com/forum/regional-forums/australia/411585-karangi-dudes-barrel-bread-oven

[Digga Don]

The design im using has the flue next to main chamber. Will this prevent from baking after pizzas if I cap the flue to avoid heat loss.

[Karangi Dude]

Hi Don,
Who's design are you using? sounds like something that Brickie in Os did

[david s]

The front and back walls of a barrel oven or kiln should be built under the vault rather than beside the vault. The expanding vault has a tendency to push the walls out. The usual method of holding these ovens together is steel bracing.

[Digga Don]

Thanks IL PIZZAILO
I'll modify my build to that principle. The oven I am copying had walls built beside the vault. I can see how it may have moved over the years but i dont know if it did as my friend sold his house and moved away.

[Karangi Dude]

Hi Don,
Here is pic of a basic layout for a good size barrel oven, the door width is 50% the width of the barrel and and works out easy to do. The width and depth of the oven is about 920mm x 920mm without the entrance area
Cheers Doug

[Digga Don]

Thanks Karangi Dude Doug. The chamfers are to assist smoke flow from the oven to the chimney vent past what would otherwise be a dead corner I assume. I will dry stack and pre-cut these before assembly.

[Digga Don]

Karangi Dude
I have a couple of question around the metal support and insulation on your barrel vault.
I'm back on the horse after two traumatic collapses of my main chamber barrel vault. Both due to my error's , the first being plastic over the formwork which prevented the premix thin bed mortar Im using from drying on the inside in the Great lakes climate and insufficient buttressing. I removed the formwork, and it collapsed 3 hours later. The second arch which had a keystone flicked out from the skewback whilst I had temporary buttressing removed and excited with progress removed the formwork again. Whilst all the top courses where dry moisture and possibly frost had entered the mortar layer of skewback.

1 I was wondering if I should put a parge? coat over the main chamber with fiberglass render mesh or chicken wire in it to strengthen the whole thing?

2 I have installed steel supports on either side of the main chamber against the bricks with 0mm calcium board on the olutside.

[Digga Don]

I'm concerned about expansion of the steel and noticed your oven is the other way around. Im thinking i should change it?