BeanAnimal's 42" build - Pittsburgh PA

[BeanAnimal]

I hope to get the upper slab poured this weekend.

Back and forth decision between metered concrete and batch mixing. The metered will be more consistent and time between first and last wheelbarrow load will be 20-30 mins at worst. Site mixed - even with a second mixer and help, closer to an hour.

No center support - so structural reinforced slab. Rebar is cheap - so I guess I will double up and build a truly reinforced slab with a #4 mat on 6" or 8" centers.

Will likely just re-attach the outside wall forms and raise them up 6" with shims on the brick ledge.

Inside forms support - a few 2x6 or 2x8 cross supports on legs that rest on the inner brick ledge.

Insulation will be cal-sil board - so no perlite in slab. Will get an #80 bag count and use what I have. Somewhere north of 4.5" and south of 6" thick.

6" puts me closer to the final height I want (floor area in front of oven may be thicker than I had designed for initially) - though 4" concrete with 1" of perlite mix (and cal-sil) and a center support was what I had planned and built for. Don't see the need for the perlite and would rather double the cal-sil if/when needed when I get to that phase.

[BeanAnimal]

Busy weekend - not a lot of oven work.

Got the rebar mat tied
Set the side forms back up, raising them ~5.5 inches.

I had the extra #4 rebar so went ahead and tied a 6” mat, in effect a reinforced 2 way slab.

A bunker needs a suitable roof, right?

Slab clear span is 58x65 -no center support.


Stating to get things tied. Several vertical pieces of rebar embedded n the walls were bent over and integrated into the mat.


All tied, temporary internal braces in place.


Wall forms back in place and raised 5.5” with blocks. Ready to pour.

Yes - way stronger than it needs to be. Having fun and enjoy the thought that this thing will be here when the sun burns out.

[BeanAnimal]

Yesterday was a huge milestone!

Ordered the volumetric truck (can't say enough positive about the driver or the company, Pittsburgh Mobile Concrete and will defiantly use them for future project ). I have dealt with some real jerks in the past - most of these guys hate dealing with DIYers and weekend warriors. These folks were the exact opposite!

Kind of expensive - but it has been hot and I didn't want to risk a cold jointed pour batch mixing.

The slab called for ~20 cubic feet. So ~3/4 of a yard.

$318 with tax for the first yard, use it or not. Then $145 a yard after that, billed in 1/4 yard increments. I used a "yard" and to be sure, they were on the VERY kind side of that, after pouring the slab and filling one footer, they left me with two wheelbarrows full for the footer hole that I didn't get finished before they arrived.

Even with the price break from big box, $4 a bag for 45 bags = $180/yd - 3 trips to haul it in the F-150 and moving each bag 3-4 times and the mixing labor. She wanted to know if I was crazy at this point, by trying to save $130 bucks. So the batch truck it was!

So glad that I did!

Photos coming next post...

[BeanAnimal]

I used the interior forms and (2) 2x10x12s (on hand for a garden project) to build a wheelbarrow ramp. This worked like a charm and would have easily supported a motorized Georgia buggy if I had one to use.


Three wheelbarrows on hand - only needed two. That two wheeler is an awkward beast and going back to Lowes unused. Good for flat ground but not odd terrain.


The ramp - just recycled interior wall forms laid over 2x10x12s. Sturdy and stable. My buddy Andy (foreground) and brother (backgroung) finishing up. Maybe 15 mins from first wheelbarrow to last! Nice!


Screeded and vibrated (Harbor Freight $99 vibrator with 20% off coupon. Highly recommended!). Any enjoying a cold drink while we wait for the bleedwater to evap.


The slab is unlikely to be seen, but I steel troweled it to make it flat and seal the surface. Here it is it wet for curing after the hard trowel.

FWIW - I did not bull float. I simply wood hand floated after we screeded.

I covered the slab with an ez-up after we screeded, but got a bit behind (my help went home) with the footers and didn't get on the slab soon enough. The left side got some (a lot) of sun compared to the bulk of the slab that was in the tent shade. Ohh well - like I said, it will be likely enclosed! It is dead flat/planer/level and 99.99% of it is as smooth as a babies bottom.

[BeanAnimal]

Forms removed this morning (June 12) and keeping it wet. The arch is perfect, no cracks (it has been 12 days I think). Interior slab supports will remain for a week or two.

Will keep it wet for a few days - I don't think it will matter - the mix was great and there is so much rebar, that I can't fathom shrinkage cracks. But better safe than sorry. My eagerness to get the dome started may change the plans for watering!



As a side note:
I mentioned footers for the timber frame - 3 feet deep and roughly 20x20 = 8.33 Cubic Feet = ~1250 pounds. So solid footing for the timberframe and plenty of ballast for uplift prevention of the timberframe. At 5000 pounds + the weight of the structure (lets call it 1500 pounds). The roof area will be ~145 square feet. So maximum uplift resistance would be 6500/145 = 44psf. I calculated worst case for the proposed structure (using skyciv) to be about 22psf (and that is basically tornado winds). So more bomb shelter engineering!

-Bean

[BeanAnimal]

There does not appear to a lot of interest in these projects anymore. These forums are awfully quiet compared to what they used to be. I guess 1000 ovens later and interest has waned. I will continue posting progress simply for the sake of finishing what I started.

I was able to set the 2” CalSil floor insulation this morning. The oven slab is dead nuts flat, but the boards did not sit perfectly flat. It appears a few of the pieces are slightly warped. I used a bit of sand to support a few of the small gaps.



I left 8 inches in front to support the landing that will end up being roughly 12” deep. I hope this is not too deep, but no turning back now.


Once everything was centered, I poured a 1” layer of castable refractory cement for added thermal mass. The floor brick are only 2” thick. I debated adding an extra 1” of CalSil and 1” of thermal mass, but opted out due to slow materials availability.

I used a metal screed after the initial 2x4 rough screed and was a bit obsessed with FLAT. I don’t want to fiddle with lipage issues with the the floor tiles.


Hopefully starting the floor brick tomorrow!

[JRPizza]

Hey, we are all still here. In general if you aren't asking questions and nobody sees you doing something that is a mistake things will be quiet except for the occasional "looking good" posts. You are a man on a mission and seem to know what you are doing so I for one am just sitting back and watching your progress. Will be interesting to see how your kit comes together. I had briefly considered doing some kind of kit but convinced myself that with building a base and finishing the oven a kit would not have saved me much time. I was probably partially correct but as you say there is lots of brick cutting getting to the stage where you have a dome and chimney built.

[Jamie Dowdall]

I'm here following along. I'm new and dont have advice to offer, but I appreciate the time you're putting in to document and share your progress.

[BeanAnimal]

Thanks for the response. I hope it is a mission and not a slow motion train wreck! I am not so sure that I know what I am doing, but 20 years of planning has to count for something! Still amazes me how little gotchas can drastically change even the best of plans. Though, One could argue that the plan was not so great to begin with. Only snag so far is ground level, I listened to her and added a row of bloc to the foundation... so will have to deal with the final standing surface mess later.

i certainly paid a premium for somebody else gathering all of the materials and shipping them in one box, but other than that the kit has very few deviations from the plans/community upgrades and practices that have evolved over the last few years. One point of concern is the 6” flue and (what i:consider) a narrow flue gallery. That said, Ben has sold/built a lot of these and they appear to not soot up the front arch. Also, due to the timber frame this is going under, my chimney will be far taller than stock, so it should draw extremely well.

At this point i am still extremely happy that I am not chasing this stuff down and reading data sheets to see if some substitute alternative that is locally available will work.also glad to not be driving around hauling supplies. Curious to see how the 2 part mortar in the kit works. I used heatstop on a fire pit several years ago and found it finicky with a very short pot life life. I hope this stuff has a better feel.

[Jamie Dowdall]

Once I learned to browse this site from the search screen so posts show up descending chronologically regardless of thread, I found it much easier to follow the live builds. I think theres a lot of people viewing the forum but not necessarily knowing how to find the newest builds.

[BeanAnimal]

I didn't get a lot done on the oven on Sunday.

I drove 30 miles to a Home Depot that stocks mason's lime.... In retrospect, I should have waited until today and sought out a local brick/mason supply.

Instead of jumping in and doing the floor - I decided to cleanup and organize the site for the masonry work. I setup a mixing table and storage container/holder for the open bags of materials (wheelbarrow with a tarp and bungies). This should make things easy to start and stop mason work each day without toting bags back and forth and getting setup and tearing down over and over.

Hopefully setting floor brick this afternoon.

[UtahBeehiver]

I can't recall, is your kit bricks or cast? Either way, yes, I'm still watching, just not have seen any fatal flaws to comment on. Keep documenting, it is a great resource for future builders.

[BeanAnimal]

The kit is bricks - very well packaged and extremely well documented. I honestly can't say enough positive about the experience to do it justice. The process and final result are almost identical to the FB plans and community upgrades that have evolved since they were published. The only real difference is the pre-cast flue gallery. I will not need to build the transition from arch to chimney

I can't tell you how thrilled I am to not be actually cutting a few hundred bricks. I think you can see how I do things.. and if I were to cut the bricks, each brick would be custom fit for uniform mortar gaps. This saves me from going overboard - That is,10 years custom fitting bricks would have been fun. Today, it would make me grumpy.

[UtahBeehiver]

Been there, done that. I had to strive for tight 1/16" joints when I did my build 10 years just to see if I could do it. Now, I tell builders, just make the inside the dome joints tight and let mortar be your friend. I have seen the cast vent of your oven and it is very nice with clean lines.

[BeanAnimal]

I got the floor brick set yesterday evening. Not happy with a few of them, got caught fielding a work call while I was working on the oven and the sun was going down. I got up this morning and pried the offending brick up and scrapped away the bedding mortar...

I promised myself I would not be this OCD and I am 1 day into mason work resetting brick that are not "perfect".

Yes, the precast flue gallery is rather nice. It is a shame that I will most likely be covering it with part of the house structure. The entry on these ovens is roughly the same dimensions HxW but a bit shorter than the FB plans I think. My stone clad enclosure plans call for a decorative arch in front of the oven arch. At least that is what I modeled in Fusion360.