42” Pompeii in San Felipe, MX

[modified9v]

Thanks for the response guys... yes, the contractor is covering the costs to re-do it. Still not a good situation as it will set me back as far as time is concerned. I totally agree that had they formed it correctly I wouldn’t have had to lay down a 3/4” thick leveling material. That was going to be stucco on top of the scored concrete.

As far as to why it failed... I have never been impressed with small town Mexico concrete. In the third picture is how they do the sand. It is basically dirt that is run through a screen... the dirt is not washed. Also, the slab was not kept wet after the pour. It is my understanding that the slab should have been kept wet and covered for 7 day after the pour. It was not. Also should note that the thing is loaded with rebar... both 1/2 and 3/8. Probably wouldn’t collapse but why take the chance. I’m mean even the contractor said it was garbage.

Anyway, it will all work out and I won’t be out any extra cash so that is good. Things happened for a reason. I pretty sure they will get it right this time. I was not on site when they did the pour last time, but I will this time. I am going to suggest that my carpenter and I do the framing of the forms. I think I’m going to have them NOT finish it with a trowel. I think the trowel work is why the thing wasn’t flat in the first place. I’m thinking that a rough surface might give the FB board something to bite into.

Oh, and thanks Gulf, resizing pics seemed to make it easier to upload pics.

Mikie V.

[modified9v]

Wellll, what took all day to make took only 15 minutes to destroy. There is virtually no aggregate in the mix. Very little sand or rock. They are pulverizing it with little two pound hammers and chisels. Nothing stuck to the rebar. So sad.

[modified9v]

So the center section busted up. Where I have the arrows on the pic is where they have been chipping away. It’s been slow going for a few hours now. When they busted off the overhanging part above the arched opening I was worried they could weaken it... not a chance. That baby is loaded with steal and the mix was real good. That stuff came out of a cement truck. Big difference in the quality of the concrete.

I think they will have the demo done and framed for a pour by this evening.

Mikie V.

[modified9v]

Update: Well, the slab was removed and the forms were rebuilt.. they poured it yesterday. These guys have a very difficult time following instructions. I will say that I’m not at all happy with the way it came out and I’m looking for solutions.The only thing better this time is that the material they used to make the concrete looked much better and they used even more rebar. It is also 2” thicker (now almost 6”). The thicker deal may have been part of the problem this time. I don’t think the forms under the slab were strong enough to hold the weight of the additional concrete and overnight it has sagged in the middle where there was no reinforcement.

In the photo with the level you can see to the right just how much it sagged. In the other photo you can see a sample of a typical crack that has formed as well. The cracking runs nearly the entire length of the pour on both sides of the reinforcement below the slab. The cracks were present last night when I hit the sack but grew overnight.

Options: Well, I can have them rip it out and get my money back and do it myself. Have them try again (not gonna happen). Once the forms are removed I could put a permanent reinforcement under the suspect areas... Or I could just say screw it and build the oven on top of this monster.

Do I think it will collapse? No. Do I think it could sag more? Yes, and that could be bad for the oven.

Questions: Would you build a Pompeii oven on this stand? What might you do?

Thanks, from a very frustrated Mikie V.

[modified9v]

I just met with the contractor at the build site and he agrees that we have a problem. Concern is that as the oven get heavier, the slab will sag even more and it will comprise mortar joints on the lower courses and they could crack. His solution is to put a heavy duty steal frame under the slab and attach it to the sides of the dry stack.

After that we will put a thin coat of stucco on the slab to make it flat and level.

Wish me luck, Mikie V.

[JRPizza]

Something to consider - other than the floor bricks, most of the weight is concentrated in the circle of the dome bricks, and outboard of that if you build a doghouse structure. If you right-sized your stand the majority of the load should be over your walls except for the wood storage opening.

[Gulf]

In your pics, I don't see anything that remotely resembles a wet concrete color. Since you are having problems with the hearth slab, are you confident with the foundation and footers that are under the oven stand? If it is substandard, all the steel supports that your contractor recommends ain't going to help very much imo.

[modified9v]

JR... The stand is a bit large as I had intended on a larger landing. Also, was planning on the dog house too... over all the oven will not sit directly on the wall, but in just a bit. Not much.

Gulf... yes, the concrete here seems too always look dry after a day... sort of a powdery look. Light grey. Looking at it this morning is does have more of a wet look. Another reason may be the “cream” on top or just a bad picture... but it isn’t like the concrete I’ve poured in the States. As far as the footer, well it is 16” deep and tied into the block wall footer. Lot’s of 1/2” rebar. I will add that the way they bend the rebar here is different than anything else I’ve seen. I asked the conctractor about it and he said that this foundation was done just like all the houses are done here. They are still standing, but still much different than I’ve seen. I think we are good on that.

He should have the steel installed on Monday, which means Wednesday or Thursday (Manana, manana). After that, how long should I wait before I can start with my floor and dome?

Oh, just wanted to add that the heat index the day this was poured was 122f. Very high dew point as of late.

Thanks guys for the help and following along, Mikie V.

[modified9v]

While I’m waiting for the concrete oven base to cure and the contractor to put in the steel beams under the slab I thought I’d tackle cutting the FB Board. Can someone tell me if there is some sort of program I can use so I can maximize my boards? The oven floor is 43” and with the gap between the floor and the first course laid I have a diameter of about 51 1/2”. When I add in the area under the vent I’m basically looking at a 52” x 52” square area. 2,704 sq inches... I have 3 FB Boards that are 24” x 36”. 2,592 sq inches... Seems like I don’t have enough, but I know it’s possible. I’ve seen it done but my search on the forum has come up empty.

Can anyone help with this?

Thanks, Mikie V.

[JRPizza]

I used a CAD program (Freecad) to play around with how to best fit in my boards (see attached link), but it wouldn't help you fit 2704 square inches of brick surface on top of 2592 square inches of board. I had 6 1'X3' boards - the same area as yours, and I had just enough to do my 39" oven with a little left over to use in my insulated door. If you can't get more board you need to think about not insulating under your vent (may not be as important if you use a heat break, or insulating under your landing but not under the vent arch bricks. I built my outer arch on top of insulation board and sometimes think long term stability might have been better putting those bricks directly on concrete. You could also use some vermicrete to supplement your board to provide additional area, in addition to adding some depth of insulation. How thick are your boards?

https://community.fornobravo.com/for...392#post380392

[modified9v]

Thanks for the reply, JR. Man, I must have read your build 5 times front to back. Really glad you decided to document your build it has been very helpful.

I screwed up when I wrote my last post on the dimensions. I over estimated a little on the 53” x 53” and it DID NOT include the flue area. I went back and remeasured this morning and it’s 49 1/4” from outer dome to the outer edge of the inner arch... then, 51 1/2” outer diameter of the dome. That is 2,536 sq in. Haha... that gives me 56 sq in to the good. No way can I make that work. Oh, by the way... these are 2” thick.

Going back to my original plan I see where I had the heat break at the inside edge of the inner arch and the math worked out... but, math is one thing and working with a circle vs a rectangle is humbling for me...

I’d really like to not have to buy another board. Them babies are spendy with duty and shipping.

Since I don’t know how to use CAD I think I will cut up some cardboard pieces and see if I can make it fit. Might even try it out on some graph paper.

Thanks, Mikie V.

[JRPizza]

2" of floor insulation might be a little light. You should do a forum search and see how many folks that went with 2 were happy with it - you really might want to supplement with some vermicrete. It probably matters more if you are going to do some retained heat cooking - which most of us do. I always cook at least 2 meals worth of meat the day after I do pizza. Usually some chicken or beef followed by slow cooked pork.

[modified9v]

JR, did look into what other think about insulation. Nearly everyone says if they had it to do over again they would use more. Man, those 24x36 boards are over a $100.00 bucks a piece by the time I get them to my door. I just can’t swing another 3 of em... I like the vericrete deal but I’m coming up empty on sourcing it. I will continue to look. I still have to get my insulation blanket too.

By the way, I’m finally happy with my oven stand. The steel girders worked like a champ. We jacked up the floor and installed them. We are now level and strong... will just need a touch of fireclay and sand to take out the small undulations... or, make a vermicrete slab. The search is on.

Thank you, Mikie V.

[JRPizza]

Yeah I went with 5" of board as I could pick them up locally, if you call a 3 hour round trip local , and saved quite a bit on shipping. It's funny that I was tracking costs down to the gnat's eyebrow till I picked up my blanket and boards - at that point I figured I was all in and stopped keeping receipts.

[modified9v]

Man o’ man... been a month since I’ve posted with not a whole lot to report. Basically, the reasons for the delay have been weather and remodel related. It was just way to hot to work in the sun. The weather here seems to cool almost every year with the first full moon of September... almost right on the money again this year. The humidity has dropped and it is now comfortable enough to work out in the yard... well, it was!!!

I ended up going with only 2” of FB board simply because of the budget. I can’t pull anymore cash out until January and I’m not waiting that long. Layout of the board took a bit as the slab is not square. I ended up having to get one more board (24x36) and I have plenty left over to do the door. It will be fine where it is and I will live with it. The height of the floor is pretty high, but I like it... tested with the peel and I will for sure need more length to work the back but at least I can see inside without bending over too much.

Funny, I numbered all the floor bricks and forgot to take a picture for reference before I took it apart and moved it from my work bench... oopppps!!! Took a bit to get it in place but there it is. Made up my first batch of the home brew and mortared the first ring together. I used the 3:1:1:1 recipe but really think I didn’t have it soupy enough... made a second batch and used a bit more water... that was way easier to use, but I’m seeing it pull away from the brick slightly. Not sure it’s a big deal because the next day it was as hard as a rock. For reference, I’m using a red solo cup as a measuring device... Turned out that the mortar was just getting hard as I was 3/4 of the way through... I will be cutting it back as I go up with the first course.

Anyway, it’s always windy here and my shade structure is not happy... it want’s to fly. Oh, and it never rains here unless you are trying to build a pizza oven. No sooner than I got the bottom ring done the sky has opened up. Should be a short storm and I will use this time to cut about 3 courses worth of 1/2 brick.

That’s all for now, I’ll get pics up when I take the cover down and bet back to work. Thanks for following along and to those that have offered input I’m very grateful.