Remember that you should also build the arched entrance to the bread oven, therefore we recommend you to use a polystyrene or plywood template. Follow the... 3. Building a Foundation 1. Step 2: Pouring the Slab. After pouring the slab and getting an inspection (building permit remember? The concrete base... 2. First thing you need when doing a project like this is a building permit. Step 3: Supporting Walls/base. The opening of the entrance should be around 1′ wide, but you can adjust its width and height according to your needs and tastes. Brick Oven Step 1: Building Permits and Foundation. Plan your foundation. The proper technique for stacking the bricks is to start with the floor, then the back, walls, and arched roof. Continue laying the bricks using clay mortar, to build the brick oven. The instructions for this form will be included in the brick oven plan. … Most brick oven plans will include instructions for a concrete foundation. Build a foundation form.