37.5" corner build in SoCal

[Zimmy]

It's been almost a year I've been working on this oven build, so I figured it's time to create a build thread to keep track of things and let you kind folks see what I'm doing. The goal is to build an L-shaped structure towards the far back corner of my 1/4 acre suburban lot with the oven in the corner of the L, with the opening towards the inside of the corner. To the oven's left is a prep counter and to the right is a bar-height counter for folks to sit on the far side and at the end. The dimensions of the two counters are to take advantage of leftover quartzite slab material I have from a kitchen remodel. I started with a 6" concrete slab over 2" of compacted road base, all dug out with a pick axe, as the ground here is ~20% river rock held together by silty loam, undisturbed since this was an orchard in the 1950's. Since we're in earthquake country and the thought of several tons of masonry falling on family or friends haunts me, I hooked several L-shaped pieces of rebar under the slab rebar to tie the vertical structure to the slab reinforcement. There are two pieces of conduit for electrical to power a refrigerator under the prep counter and an outlet (phone charging) next to the bar seating. I'm dry stacking 8x8x16 CMUs for the structure. The second photo shows the initial layout . We got in a rush at the end of the corner slab pour, so a few pieces of vertical rebar ended up in the wrong place. I don't think anyone will notice them cut off in the wood storage area.

[Zimmy]

The prep counter is farthest from view of the guests, so I started there to get my learning curve taken care of. Every other vertical cell got filled with grout, adding extra when needed for corners or vertical rebar. Half a 5-gal bucket is about all I like to carry/pour. A bond beam on the top course ties everything together for shear loading. I will eventually cover it with HardieBacker cement board bedded in mortar to support and level it, secured with TapCon screws into the grout, then polyurethane construction adhesive will hold the quartzite in place. This is one place on the property the termites won't get to! If you are thinking of getting a diamond blade for your grinder to cut your CMUs, the segmented one makes a world of difference for cutting speed and still gives perfectly acceptable finish since it will all be under stucco anyway. Wear your respirator, silicosis is no joke.

[Zimmy]

While the prep counter will get an angle iron lintel to clear the refrigerator height, the oven and bar are higher and will get CMU lintels. I plan to put a decorative brick arch on the wood storage area to match the decorative arch on the oven. There were three triangular areas that got closed off under the oven. I thought about installing a time capsule but other priorities won out. The slab on top of the oven CMU structure is 3.5" of rebar-reinforced concrete topped with a 42" diameter ring of 4" thick vermiculite concrete for a brutalist-inspired total slab thickness of 7.5". Thanks to those who have gone before me for the reminder to shim the legs of the slab support so they can be removed easily. I foolishly added a curved area to the front of the slab which created issues with room for my arches and landing area. I also added a 3/4" chamfer to all edges just to make things more complicated.

The slab forms have a 2" reveal from the exterior wall of the CMUs to allow 1" for stucco and a 1" final reveal. This allowed me to screw the vertical 2x8s to the lower horizontal 2x4s to prevent the form from bowing. A 2x2 on the top exterior rim kept the upper area from bowing out. It was ~1/4 below the top of the 2x8 to not interfere with screeding the slab. Five 1/2" PVC drain molds were held by blind holes in the plug covering the wood storage area. No release agent was needed to remove them, just a pair of vice grips to twist out of the vermicucrete.

[Zimmy]

I have lots of ideas, most of them bad. One good thing I did was place the cement mixer on top of the prep counter so it could pour directly into the form instead of lift each pound of cement twice. Ratchet straps held it firmly in place to the pallet I nested into the CMUs. I already carried it from the shelf in Home depot to the cart, from the cart to my car, from the car to the wheelbarrow, from the wheelbarrow to the back of the lot, into the mixer. One less lift for my old body. Thankfully my buddy from New Jersey was in town and was able to help me with the pour. Unfortunately I did not vibrate the concrete next to the form well enough and got a terrible finish on the edges. For the slabs I used a DIY vibrator of a slightly bent piece of #4 rebar chucked in a drill motor and set inside a piece of iron pipe. That consolidated the concrete beautifully. For the oven upper slab I used a jigsaw with no blade on the sides of the form, but it was not enough. I should have whacked it with a rubber mallet as well. Oh well, the good folks at r/concrete suggested Sika 123 Plus as a fix for that.

[Zimmy]

Now we can actually start building an oven! Ignore that I have not poured the lintels or bond beam on the bar. That will come later once I feel like lifting more bags of mortar. My local masonry supplier only carries Whitacre Greer low duty fire bricks, which caused me great anxiety since the Pompeii oven .pdf instructions say to use medium duty fire bricks. But this thread assuaged my concerns about the performance of these bricks. I didn't have enough old Shuttle tiles in my office to use for the oven, and they are too delicate anyway. I originally planned to build a 42" oven, but realized that a corner build is really inefficient for space that the entry arches need, and scaled it down to 37.5 in the hopes of squeezing in a decorative arch to my curve-encumbured slab. I tapered the landing under the dome arch 1/4" over one brick length to allow a slightly better view factor into the oven and simplify removal of the arch mold. The floor was bedded into a 50:50 mix of sharp masonry sand and Lincoln 60 fire clay from the good folks at Aardvark Clay. My favorite tool setting (reworking, actually) the floor bricks was a $0.25 fork from the thrift store! This brought step and gap measurement flashbacks from early in my career! My buddy welded me up a IT using a Harbor Freight clamp and bits and bobs from his garage. I made sure the center line of the bar is in-line with the center of the face of the brick to avoid stepped bricks.

I ended up with a 19.25" wide and 12.125" tall dome arch opening, which is 65% of the oven height. Pretty close to the preferred 63%. Thanks to JRPizza for helping me out with that. I cut the length of the 1st dome arch brick (level with cooking surface) down so that it only protrudes 2" from the oven OD to buy me more space in front. I plan to have a 1.5" reveal and overlap the dome arch with the vent arch by 1.5" to incorporate a ceramic rope seal to thermally and structurally isolate the vent arch from the dome arch. If I get lucky, I may just have enough room to fit a thin decorative arch in front of the vent arch. I plan to use a 6" diameter DuraVent anchor plate, which has a 10x10 footprint. Unfortunately the fastener spacing is not specified. Let's assume it is 3/4" in from the edge of the flange. So a 9" brick + a 2" extra piece + 1/4" grout line gives me 1-3/8" from the fastener centerline to the edge of the brick. I think I can live with that.