Adding Gravel to Pizza Oven Foundation Prep - Backyard Wood-Fired Oven - March 2024

The last progress-report on our backyard pizza oven was earlier in March when I showed the cut-down concrete slab framing pieces (2x6's) that I cut to the final dimensions (Slab: 78" wide, 86" deep. 6.5' wide, 7'2" deep. Stand: 72 wide, 80 deep - 4.5 blocks wide, 5 blocks deep).  In that post, I talked about the next step is to fill the excavated cavity with gravel ahead of the rest of the slab prep.

I went over to Menards and picked up 10 0.5 cubic foot bags of their multi-purpose gravel.  Each bag is supposed to cover about six square feet.  I wasn't sure how far these ten bags would go, but I figured that was about the limit that I wanted to push my car weight-wise.  

I brought the ten bags home and hauled them (one-by-one) to the site and piled them up:

Opening each bag and spreading it out, I quickly discovered that I was FAR short of the amount of gravel that I REALLY needed to complete the project.  Below, is what the site looks like after ten half-a-cubic-foot bags of 1/2" gravel:

Now, as a refresher...this is built on-top of our drywell, so the gravel here is LESS about moving the water away from the slab and more about creating a level site to pour that concrete.

I also bought home 10 8x8x16" concrete blocks to begin to lay out the bottom of the stand, but I'm using one of them (in the photo below) to figure out the stand layout in relation to the drainage pipe.  I want to be able to place the frame on top of the gravel to allow for the stand to sit in a position that would have the inlet be on the 'inside' cavity of the stand.  

I suspect that I need eight-or-nine more bags of gravel to fill in the bare spots and to level-up the left side of the site.  That left-side is where the drywell tapers-off, so it required more excavation than the right side. 

In terms of what has been done (so far), here (below) is a look at the 2024 [Pizza Oven] posts:

My DIY Backyard Wood-Fired Pizza Oven Progress:

• I reviewed a couple of potential sites for the oven.  I've settled on the drywell location.
• I built a scale model of the cinder block stand using LEGOs. 
• I found some brick pattern inspiration on TikTok that I'm thinking of utilizing.
• I went back-and-forth about 10" vs 8"-wide blocks for the bottom courses and using L-shaped corner blocks.  I've decided to use 8"-wide blocks and NOT use L-shaped corners. 
• I used my post-hole digger to try to find the depth of the top of the drywell.  Turns out, it isn't very deep in some parts.  
• I listed the pizza oven as my #1 'early' priority.  Talk about a forcing function to sort-of WILL this thing into creation.  
• I began to think about renting vs. buying when it comes to concrete mixers including one from Harbor Freight.  I still am unsure about what direction to go.
• I began excavation on the drywell site.  There are a few considerations including existing plants and drainage that I've begun to navigate.  
• I hauled off what appears to be more than a yard of topsoil and turf from the site.  And piled it (turf-side-down) in the stumpery.  Covered with wood chips to reduce light.  
• I went back to Menards to figure out the rest of the building materials.  Including high-heat mortar, rebar and pressed bond beam blocks.  
• I cut 81x86" framing (for a 78" wide x 86" deep slab) and set it in place to decide final location and if I've done enough excavation.  
• I put down ten (10) bags of 1/2" gravel.  That wasn't enough, so I'll have to buy another round of gravel before proceeding with the framing.

What comes next?

More gravel.  Then, drainage pipes (a couple 2' sections of 6 or 8-inch pvc) and setting the framing.  I need to buy some nails to use to assemble the framing.  Finally, a few more cinder blocks to allow me to complete the first course. 4 more full blocks, 2 half-blocks - that should get me enough to complete the layout.  

Then, slab prep including:  vapor barrier, rebar (with ties and chairs) and a metal grid.   Need to decide on drainage for back two chambers and/or if sloping to front drain is appropriate.  

Once that's done, it is time to pour the slab.  That means that I have BOTH have the bagged material (48 bags of 4000 psi concrete mix) and the mixer on hand.  

From there, I can move on to the stand construction and (potentially) backfilling against the slab (with a potential french drain). 

Spring Break is a'coming and I need to find time to get the materials and make-a-call on concrete mixer rent vs. buy.   Time to get busy living (with a pizza oven) or get busy dying (without one).