Sizing my build

[Ronny82]

So I am in the planning stage, ready to start the base. Seeing as i have no friends with ovens, I have no manner of truely looking at completed ovens to get any perspective of size and ability. I have been reading and reading and reading, but I cannot decide on size.

I cook for 8 every day, 4 adults and 4 teenage hungry buggers. I want the multi stage cook, which comes down to thermal mass, and insulation to achieve optimum results. But how big?

I'm thinking a 1200 or 48" dome will provide all the versatility I could dream of. But, could I go smaller? Room is of zero issue and it will become part of a Wood fired outdoor entertainment area.

Of course I will have more questions later on, but for now, I just really need advice on deciding size. The oven is phase 1, and size basically depicts start point of the area as a whole.

Thanks in advance
Ron

[UtahBeehiver]

That is a tough one to answer, a 48" ID oven is VERY large and typically leans more towards a commercial size. It will take substantially more wood to saturate and fuel the oven. But if that is the size you think you need and will be firing the oven a daily or regular basis to meet you cooking needs then nothing wrong with it. Karangi Dude (originally from Coff's Harbour) did a top notch 48" high dome but he also taught WFO cooking classes all the time. Look at his build thread, he has done 3 ovens but the 48" is number 1. Multi day cooking really comes down to using the right amount of insulation. Heavy thermal mass is geared more towards bakers or production cooking

[deejayoh]

48" is a huge oven. I have a 39" (one meter) oven, and it's plenty big to feed a large family. I've done steak dinners for 20, pizza parties for 80, 10 loaf bread bakes.... food to feed the whole neighborhood. As Utah suggests, better to focus on insulation and heat retention, so you can do multi day bakes - or be able to refire it in short order. If I fire on consecutive days, my oven will clear in 30 mins on day two. Another thing you might want to consider if you think this is going to become a primary cooking device (rather than just entertainment) is adding a gas feed. Much easier to use every day with gas, and you can always throw in a bit of wood for flavor.

[JRPizza]

I also built a 39" oven and think it is a good compromise of not too big and not too small, and some of the numbers worked out very well which makes me think 39 might be the "ideal" size. I took the FB recommended sizes of door from a 36 and a 42" and interpolated to get a door height (see below). Notice the door height for 39" is very close to the ideal height of 63% - I took it as an omen . Also if you check out my build you can see that at 12.25 high and 19.5 wide you can make a perfectly half circle arch (@9.75 radius) that sits on a full brick (2.5").

Inch	ID	Height	Width	Height
36	36	18	19	12	66.67%
39	39	19.5	19.5	12.25	62.82%
42	42	21	20	12.5	59.52%

[Ronny82]

I think my brain has been overloaded after reading these builds. I'm in awe with the quality of workmanship, but it is something I wish to attempt. However wife prefers the dome look rather than the enclosure. So let's say I decide on going smaller as suggested, let's work on 42" as I can always go down to 40, but can't go bigger obviously. For insulation, I was thinking going commercial, 4" CalSi underfloor, 4" blanket over dome, plus 2" perlcrete, plus 1" finishing render. Does this sound feasible.

Thanks again
Ron

[UtahBeehiver]

Happy wife, happy life so I see a dome in the making. The insulation amounts are high end of the scale (beyond this is diminishing returns) so you should be able to get multi-day cooking out of the oven with ease. Being a dome, you do need to design in means to keep the CaSi from wicking water from the hearth, ie weep holes in the hearth, raising CaSi slightly off the hearth. You should be happy with either a 42 or 40" oven, these are still large ovens.

[Ronny82]

Thanks Utah. Fortunately I am only in the start phase, I will bore everyone with construction questions later lol. Where I'm at now is, 42" oven, and 12" wall, equates to 66" width. I'm taking a stab in the dark and am going to add another 12" depth to allow for chimney arch. So 66x78 is the base I need to build to accommodate oven. Atleast i have an area to work around an get started now

[UtahBeehiver]

The hard part for you downunders is finding materials either affordable or available. But I have seen several resourceful Aussie builders that are great scoungers and repurposers. Start stockpiling now and look out way ahead for materials needed in the build maybe not needed right now but later on.

[Ronny82]

I'm.honest not expecting it to be cheap to build, as such it will be a long project. Basically whenever I have $200 spare I plan on buying whatever I can with that and build a stockpile up as u suggested. I think I have worked out stand size now, will see if I can get a pic to load to get your feedback if you don't mind. Wife has changed things on me again and has decided on a corner setup now

[UtahBeehiver]

I did a 42" corner build so you can look at my thread and it will give you design ideas for a corner oven.

[Ronny82]

Thanks for that mate. I will look it over after work. Let's see if this works, hopefully photo attaches. An extra bench is being added to each end, top left as a work bench and off bottom will be an area for either a gas or wood grill. I want wood ofcourse but for convenience gas may be a more convenient option.

[JRPizza]

Ronny, not sure why your are dividing up the space under your hearth slab, but you might want to consider not blocking it off. I don't think internal support is needed for strength (most of the weight is distributed around the mean diameter of the oven), and I usually fill the space with firewood to save me from walking back and forth to the wood shed.

[david s]

Ron,
Not sure if you are building into a corner with existing walls, but if you are be careful not to have the oven placed too tight into the corner if you plan on an igloo style. It becomes really hard to work around the back half of the oven. Additionally you will be left with an unusable space behind the oven in the corner. If you do have existing walls an enclosure style is a better option.
I also think you should consider going smaller unless you have a forest nearby and you enjoy spending a lot of time cutting and splitting wood. I regularly fire my oven to cook just two sourdough loaves (how much bread can one family eat in a day?) and my 21” oven would use around 2kg of wood to do that. You won’t be firing up a huge beast for one roast meal or for three pizzas. Smaller ovens also require way less materials and labour resulting in a far cheaper build.
Dave

[Ronny82]

JRpizza, 2 reasons, 1, most builds I have seen so far for corner builds have done similar, that said I do like Utah's stand and may play around with my ideas again 2, as the oven will end up completely suspended I don't trust concrete enough to not have extra support.

[Ronny82]

David. I am starting the build in a completely open area, with 0 restrictions. Plan is to have a kinda triangle roof setup over the entire area so during the build the most I will have to deal with is a post at back corner and the roof.

As for size, I have primarily gone large in size due to quantity I cook at once. I am quite fond of allowing for leftovers, being as both we and I work full time. Its not unheard of for me to cook a brisket, pork and lamb shoulders at once. Great for making quick pies during the week.