Increasing thermal mass ideas..?

[Ruben]

Good day to all, I scanned the existing threads but couldn’t find any info about my dilemma. I currently have a fire brick oven with a 44” internal cooking area. The dome is is constructed with 2.5x4x8 fire brick layed horizontally. It’s insulated with 4” perlite cement mix and a 2” stucco outer layer. I fabricated a 1/4” steel plate door with refractory internal lining.
my dilemma is that my oven is not storing enough heat for my long cooking purposes. my original intention was to use the oven for cooking large meat portions such hole piglets, lamb, etc.
I’m having to add more wood to during the process to complete the cooking.

My 2 ideas are: both require removal of the stucco and insulation only leaving the fire brick in place.

1st. Apply a 4” layer of clay, straw and sand mix directly on fire brick. Allow it to cure then add 3-4 inches of insulation (either perlite/vermiculite) then the stucco outer finish.

2nd. Using refractory mortar, attach a layer of solid clay brick directly on fire brick . Then , same as above, add 3-4 inches of insulation (either perlite/vermiculite) then the stucco outer finish.

Any thoughts, recommendations or critiques are appreciated.

[JRPizza]

Ruben, can you add a sketch of the cross section of your oven? When you say the bricks are laid horizontal, I am not sure if the shell is 2.5 or 4" thick. Also how was your floor constructed in terms of brick thickness and under floor insulation. Folks can help you better if they understand the total build.