Hello from Oklahoma

[patngayle]

Hi, I wanted to introduce myself since I have been reading and studying for the last few months getting ready to build an oven. We live on what's left of the family farm (about 100 acres) in a suburban community south of Tulsa, Oklahoma.

I started about a month ago and am somewhere about half done. I just wanted to thank the folks for showing photo's and answering questions from the new people since I have been able to listen in and learn a lot.

I'm doing a bastardized (can I say that?) oven based on the pompeii, but I built a round base and filled it with sand before doing the structural and insulating base. Since we have a large family I built a little larger than some others- the inside diameter of the oven is 44". I'm not sure I can figure out how to link some of the photo's. But if I'm successful and any of the members see something really out of whack, I'd appreciate any input before I make any terrible mistakes.

This might get to the photos- picasaweb.google.com/patngayle/OutdoorOven]Picasa Web Albums -


I probably won't post a lot, but I sure appreciate all the information,

Thanks Pat & Gayle

[Breven]

Re: Hello from Oklahoma

Guys-

Welcome to the forum...and thanks for sharing the pics. Very interesting design..I dig the all natural stone that you plan to cover it all with- very cool. Looks like you're almost done!
By the way, I used to work for PennWell in Tulsa, on Sheridan. Been through Jenks a couple of times too...
Keep posting! I'm sure we'll all like to see how this turns out.

[dbhansen]

Re: Hello from Oklahoma

Welcome! Looking good so far. Here's a linkified link to your photos.

I thought using an old wagon wheel as a concrete form was a rather unique idea, until I took a closer look....

[christo]

Re: Hello from Oklahoma

Very good progress!

I like the base design, it's going to look really nice with the stone facing. Are you covering the base with rock found on the property?

Christo

[patngayle]

Re: Hello from Oklahoma

Hi,
Yes the rock is exposed sandstone that the creek has washed out over time. I just went to the creek with the tractor and brought back a couple of scoops with the front end loader. I had origionally planned on facing the base with stone and the oven itself with stucco. I guess I will wait and see how it looks with the stone base.

We are lucky to have the natural materials on the property so I thought why not use it when I would have to pay $300+ a ton to buy stone shipped in from another place.

I'm in a bit of a pickle with the oven opening/door. I didn't think ahead enough and I'm not sure I have enough room on the slab to support an opening for the doorway/chimney assembly. I guess I will have to improvise something. I'll show in later photos what I end up doing.

Anyone else use buttress' in their ovens? Maybe a bit of overkill methinks.

I did add another more recent photo or two of the base more finished in the link.

[jengineer]

Re: Hello from Oklahoma

I'm in a bit of a pickle with the oven opening/door. I didn't think ahead enough and I'm not sure I have enough room on the slab to support an opening for the doorway/chimney assembly. I guess I will have to improvise something.


Pat - you have enough room that you can build up to the front area and create a landing to match. I bet you can pour a foundation in front of the oven to support an extension for a landing. Just what your back wanted to hear - another foundation. An option would be to use a fence post support structure to float a landing up to the front of the opening.

The only change that the forum would have suggested is to use more insulation in the base rather than less. You are correct that the sand will soak up the heat but that means more wood for the fire to get the floor up to temperature and to keep it there. If you are looking at bread baking that may be ok however the rule is insulate insulate insulate. If you have not built up more courses on the dome you are at a point where your could pull up your floor drop in a couple inches of insulating board and relay the floor. It would mess with your entrance way...

je

[patngayle]

Re: Hello from Oklahoma

Thanks for the input. I will probably do some sort of small slab in the front of the base to build it up. I may very will add some t-posts as a support they would fit into the process and never be seen since I'm covering the base with random rock. Thanks for the idea.

On the issue of the insulation depth, I guess I miscalculated the value of using the base as a heat reserve. Since we have about forty acres of hardwood trees on the property I don't think wood will be a problem, just the pain of having to burn a fire for longer prior to cooking. Since its primary purpose was for bread, with pizza as a great perk, I guess I probably won't tear up the floor since I'm not sure I could ever patch in along the edges after putting in more insulation, so I guess I'm stuck with having to fire it for longer on the front end of the cooking process.

But thanks for the input. I guess my thinking was off in attempting to use the base as a heat source as well as the bricks.

If anyone else sees any other problems please let me know since I have been working on the rock facing on the base ever since I realized I was going to have problems with the opening. I have not laid anymore firebrick till I figure out what to do with the opening. Thanks

[patngayle]

Re: Hello from Oklahoma

P.S. I am really going to add lots of insulation on top.

[jengineer]

Re: Hello from Oklahoma

The problem with the lack of insulation is that you may also be heating up the base and facing stone. Your stone fins will act like fins on a heat sink for transformers and the sinks for pc CPU's. They will pull heat away from the oven. We highly advocate oven isolation through insulation. Both the oven dome and the base below your floor mass are insulated. Now to figure out how to reduce the amount of heat loss.

You might want to think about leaving the last 2 courses of cinder block as it is until you have fired the oven a few times. Depending on how much heat transfer you get you may need to engineer a band of insulation.

here is your linkage picasa album - thanks for sharing
Picasa Web Albums - Pat - outdoor oven

On a lighter side did you do the shirt yourself. If so I am impressed very nice tying and dying!


I am slated to be on a business trip in Oak City October 6-16th. Stuck in the state for the weekend no they won't send me home for the holiday. looks like a road trip may be in order.

je

[patngayle]

Re: Hello from Oklahoma

We did make tie dyes over 4th of July, but this one was purchased on ebay. It is way way too detailed for us to accomplish.

Sounds like I really do need to tear up floor and add more. The heat sink metaphor really hit home. I don't want to, but. . .

The reason I only did the insulation two inches was that the oven floor ended up being higher than I wanted. What if I remove hearth bricks and replace with another inch and a half of insulation and then do floor in splits? Would the splits retain enough heat or do I need to stay with the full size brick in the hearth?

I guess I can just build up the surface in front of the oven with another couple of inches of fill so I can work in the oven comfortably. Anyhow let me know what you think about the possibility of using the splits.

Its to late for the suggestion regarding the rock. I got busy over the holiday weekend and its finished up to the concrete support floor, or thereabouts. So I'm going to have to address the floor insulation issue from the top. I did stop at the fouth level of half bricks on the actual oven so I can still remove floor to add insulation.

J if you are stuck in OKC over a weekend and want to take a road trip. Tulsa is about and hour and forty five minutes up the turnpike. You would be more than welcome to visit the farm

Thanks for the input. I don't want to do all this work and then have an oven that won't cook well.

[jengineer]

Re: Hello from Oklahoma

I shot a note off to CanuckJim as he is our resident bread baker. What I would like is some of our other builders to chime in on this discussion. This thread may get better reception over on the Pompeii Oven Construction section...

As for the splitting the floor I don't think anyone has done that. You would be forcing heat quicker into your insulating layer and if the insulating layer is not up to the challenge then you are heating up base and sand. Since the dome is resting on the floor you will have a dickens of a time getting the edge floor pieces out - it would require a bit of contorsion to get a cutting wheel in there to cut out the perimeter. So how about adding insulating where you can?

Hre is where I need others to chime in!

I am assuming you did not cement in your floor and you have more firebriack available. Pull up the full floor bricks where possible. Trim out the partials where it is not too tough. Add in the cement-pearlite insulation up to the level of a full brick. Relay the floor. This poses one slight problem and theat is the entrance way. If you use a full brick then your entrance has just gotten lower in height. At the section of the dome that makes up the entrance slice your bricks at an angle so that you maintain the full original height but it ramps up once you are inside the dome cavity. Since you are not too far up in your courses you can agjust the rest of the dome to maintain the original interior height.

OK forum member what do you think?

Modify the dome to get more insultiion under hte floor or bag it and build it as originally planned - after all sourcing wood for the oven is not a problem.

je

[CanuckJim]

Re: Hello from Oklahoma

I'd really have to second what je says about base insulation. Although it might seem like a massive amount of (re)work and mess, you simply won't get proper retained heat performance from your oven without under floor insulation, and lots of it. The trick is to isolate the hearth from surrounding masonry materials with some sort of insulation band. As well, if possible, you could retrofit high heat unsulation board UNDERNEATH whatever layers you've already done, but only once the oven is definitely dry and cured and fired (several months).

You may have forty acres of forest, but my guess is you'll be cutting down the shrubs around the house when that runs out.

The trick with retained heat baking is just that--retention. Without sufficient underhearth insulation your heat drop off curve will be very steep, and you won't be able to get multiple bakes out of one firing. Just maybe, depending, you'll find the temp drops to fast during just one bake, with the resultant loss of volume and good crumb.

This remains true even if you plan for tons of insulation on the dome. After all, it is the hearth on which the baking is done. Insulating one part and not another will not work.

Really, I know it's a pain, but do the insulation now. You won't regret it.

Jim

[Wiley]

Re: Hello from Oklahoma

Here's a suggestion that might save you alot of work and get you cooking with less fuss than tearing up the whole floor.

It looks like you used clean sand for your slab support. And from the detailed photos you should be able to locate the positions of the rebar in the slab.

Bore several 2 " diameter holes thru your floor in locations where you will miss the rebar. Use carbide hole saws and a heavy duty right angle drill like they use to bore holes in studs for wiring a home. These drills usually can be rented the hole saws themselves will be junk when finished with this and you may go thru several.

Now comes the fun part: Break up the sand using rods and vaccum out the sand using a shop vac. You might try building a nozzle much like a suction dredge, wherein you would take a piece of 1 1/2 inch PVC pipe and bore a hole in the side to accommodate a piece of copper tubing. Bend the copper so it is centered in the PVC and extends slightly below the bottom end of the pipe. Then flare and attach an air line to the copper tube outside the side the PVC pipe. Attach the 1 1/2 inch pvc pipe to a suction line of a shop vac and suck the sand out. The air breaks up the sand and the vaccum sucks it out. You might have to get creative with bent rods to break up the sand. Once you get two holes connected the job should go quicker as you could force air in one hole (using bent copper tubing for the angled end) and suck sand out the other.

Sounds a bit harebrained perhaps but I would try it before ripping up the whole floor as that would be hard to do without tearing up the oven.

I would suggest starting with a empty vaccum and keep track of how much sand you remove. But when you get the sand out refill the space with loose vermiculite or perlite. You do have the column in the center that still will act a a heat sink but that would be a lot less than what you have at present. If you get most of the sand out you will have quite a bit of insulation beneath the hearth. Plug holes and cook.
Wiley

[Wiley]

Re: Hello from Oklahoma

Second thought and easier: Cut a hole in the outside (six by six inches or better) and get the sand out. Patch hole, you are using river rock knock so out a large one in the back where it won't be seen or a noticeable and close hole with a similar sized rock. Bore single hole in top and fill with vermiculite or perlite.
Wiley

[jengineer]

Re: Hello from Oklahoma

Hey Wiley - I like that idea. His base has lots of rebar and should hold up nicely. He also put in a centre column so there is little chance of any movement. Since this oven is for retained heat it woulde be fine to have that mass of the base heat up. There will be heat loss around it if it is not insulated but at least you now have a solution to getting the floor insulated properly.

Pat - CanuckJim made an Alan Scott bake oven which has insulation under the concrete floor for a mssive heat. The set up there is insulation stuctural concrete which is a heat sink and then firebrick. After he got the oven up and running Jim found out that he was losing heat from his insulation layer and he had to engineer more insulation under the oven. Wiley is doing that with his suggestion. You will still have areas of the oven that may not be insulated but the majorbad actor has been mitigated.

je