Rebar Installed for Pizza Oven Hearth - June 2024

The last I posted about my DIY backyard wood-fired pizza oven, I shared how I made and mounted the forms for the reinforced hearth on top of my cinder block stand.  With the forms set-up and square (and level), I began to finalize the rebar setup.  I ran a couple of rows around the flow-thru bond beam blocks that made-up the top row of the stand.  Before doing the rest of the rebar, I laid down a couple pieces of vapor barrier on TOP of the tile backer board segments.  Once in place, I ran vertical rebar up the filled cores from the foundation slab, through the block stand and out the top.  

I tied a grid of 1/2" rebar together and spanned the hearth with seven pieces each direction.   I used zip ties to tie them together and some block fragments to elevate the center part of the grid.  On the edges, I tied this rebar grid directly to the vertical posts.  

Once that was done with the rebar, I cut up some one-foot segments of 1/2" pvc and drilled holes through the tile backer board to insert these pipes for weep holes.  See below for a look at the rebar and pvc drain pipes in the heart:

I felt pretty confident in my forms as I used those 2x4's as 'stiffeners' around the edge, but as a backup measure to protect against the forms from bowing, I used some old espalier metal wire and tied each of the paired sides together.  See below for a look at this wire reinforcement in action:

The wire probably isn't needed, but I had it on hand, so I figured....why not over-engineer the forms.  Below is a final look pre-pour: Vapor barrier (partial), 1/2" pvc drain pipes, plenty of rebar and a pair of criss-crossed metal wires to pull the tops of the forms together and protect against bowing.  

Next up:  build a platform for the MudMixer, then pour.   Once the hearth is poured, we get to move on to the ACTUAL oven building.