Design phase of my new WFO at the Cove

[tommo21]

Hi All,

I want to start a thread to document the design process of my oven as it evolves and to benefit from the input of all the experienced builders on this site. Please feel free to raise any points i may be overlooking as i plan. Thanks in advance.

Here are the plans of my design so far:

1. It will be a corner orientated oven
2. I will be constructing a dome and cooking floor out of fire brick (which i read are exy in Australia)
3. It will be protected from above via pergola roof, but may catch some wind driven rain.
4. The size i am thinking is 1200mm or 47" - i need to read some more on the pros and cons of oven size, which leads to
5. The oven will be used for all types of cooking, i cook outside at all opportunities. i plan to cook Steaks on a tuscan? grill, roasts, foccacias, the odd loaf of bread. But pizza cooking will be the primary purpose of the oven.
6. i do want to finish the surrounding area with concrete benches (polished or tiled) and maybe a feature piece of stone at the oven landing - preferably at of near cooking floor height (but this is not at the expense of drainage problems - i do not want water on or near my fire brick) I remember seeing a build where the hearth was poured with a recesses area for the oven, is this the best set up? or can i pour in two parts - hearth then bench tops.
7. Flue will be SS triple skin (not sure of best size yet)
8. Finally the finish i am leaning towards is a tile mosaic finish similar the the FB Vesuvio. i am thinking either to leave the igloo shape and tile this, or build a freestanding brick enclosure around the oven in a cylinder shape and either use attractive face brick or mosaic this also. I also like the band of copper around the base (i saw another FB build incorporate copper also, looks the goods). I also like the overhang over the oven opening. But i still want to have the flue at the front of the oven like the plans show.

Thanks for reading, I need to firstly get the size right the dome shape sorted and then the technical stuff can be nutted out.

Any input or comments welcome.

Cheers

[tommo21]

Oven floor versus walls

I have always watched with interest the discussions on whether the oven floor should be inside the dome walls or if the floor should extend under the dome floor.

The plans talk about a cut in floor having better thermal performance. I assume this is because the floor bricks have a gap to the dome bricks, then insulation and therefore maintain their heat because of the extra dome brick.

The thing i have read that is of concern is that some people note burning the base of the pizza before the top is cooked. Is the cooking floor being too hot an issue? or is the shape of dome more to blame here?

Would extending the floor under the dome help even things out by contacting the floor and dome bricks?

Cheers

[david s]

Hi Tommo,

1. Be careful if building in a corner if you have a wall or fence on either one or two sides. It is hard enough being close to one wall once you get the insulation on and then have to do the outer shell.
2. You may like to consider solid reds for the dome, but firebrick is preferable for the floor.
3. Good plan. You don't give your location, but keeping a WFO dry is preferable to having to dry it out after heavy rain periods.
4. 47" is a big oven. I'm a fan of small ovens and I'm of the view that their many abvantages far outweigh those of big ovens. But it depends what you want to cook. I regularly cook for parties of 40 people or so in my 21" mobile oven, pumping out two min pizzas one at a time. They cook as fast as I can prep them and guests share whatever comes out. If you want to sell individual pizzas on a commercial scale that's a different story.
5. If you want to fire up the monster just for a few pizzas for the family, you'll probably only bother doing it once, unless you have a good supply of free wood and willing offspring to cut and split it for you.
6. A recess in the supporting slab is fine, especially as you have your oven under cover. I have a drain hole in the bottom of my supporting slab to assist moisture elimination from the underfloor insulation.
7.Double skin should be sufficient, but overkill if you must. Stay away from any timber on your pergola. 21" oven needs 5" flue, 36" needs 6" and 42" needs 8" 47" probably 10"
8. Decorative only, your choice.

Hopes this helps you.
Dave

[UtahBeehiver]

I second David S, a 47" is really big, Floor cut inside of dome on floor works either way, the most important part is the floor and dome are insulated from the concrete hearth.The gap in the floor cut inside is an expansion gap. Not sure what you mean by extra dome brick? Floor heat typically is lower than dome heat, so cook you crust to where the bottom is just right then you can finish the top by what we call "doming" use your metal peel and raise the pizza to the top part of the dome, a few seconds there and the top is cooked. Lots of times people piling on the toppings which makes it hard to cook the pizzas, the old saying, "less is best".

[tommo21]

Thanks Utah,
Is there anyway you can see that doming could be avoided by design? Obviously a lower dome height would assist.
Cheers

[UtahBeehiver]

Doming is a tool not design flaw solution. WFO are finicky animals, if you have the time and patient you can always try and equalize the oven temperature between the floor and dome but it is nearly impossible with a live flame.I am not sure you can build a WFO that has perfect temperature control. You could go with gas, no that FB has a gas version.

[tommo21]

Thanks Utah, Wood oven is by far my preference.
I would like to build a fairly low dome anyhow, and as such i will aim to have a vertical section of brick work at the floor - dome junction.
The plans give a few options for starting off. And I have read a few threads about how this is best approached.
I will begin to draw some plans up.

[tommo21]

This is the general layout of the area.
The oven will be positioned on top of existing retaining walls and it will be at the same level as a lawn behind. A pergola will cover the oven mostly.

Two issues i am anticipating early are; moisture wicking and possibly smoke staining to my pergola ceiling which will be painted white.

To address wicking i will use a moisture barrier beneath the hearth slab and beneath the floor insulation layer, i am considering adding a layer of porous blocks or boards (like foamglas or equivalent in Australia) under the insulation layer - i saw this used by another builder and using a concrete additive like Xypex.

The smoke issue i am a little less sure about. The ceiling will be 2.5m above the oven floor. Does anyone see a problem here? Logic tells me that if the oven is flued correctly there should be minimal smoke from the front. And some ovens are used indoors so i hope this will not be problem.

The plan shows the still large 1200mm or 47" oven. I will be reducing this somewhat. maybe down to a 42" i think was suggested.

Then i really want to check the ease of reach in to the oven to optimise the landings.

[tommo21]

I am leaning more and more towards a low dome height style of oven.
Can a full or 3/4 soldier course be stable without butressing?
I was reading through a few builds that had what looked like 2 full height soldiers with a metal band around the top course.

[tommo21]

The arch shape also seems to be built in a few different ways, some with straight sides others in a true arch shape.
Can those builders who have been through this decision help with there any notable pros and cons of each style?
Build ability or ease of use when cooking?

[JRPizza]

Tommo, I went with a higher dome oven to get the tallest door height I could while maintaining the door/oven height ratio needed for the oven to breathe (mine is ~63%). I am a pizza nut and have been since I was a kid, but wanted to be able to get a big turkey or large roasting pan through the door, and didn't want to ever wish I had more height. You mentioned using a tuscan grill - door height will be handy when you are reaching in to turn your meat. I don't know of anyone that built a high dome that wished it was a lower one. As for arch style, I did a hemispherical one mostly for looks and to copy the builds that I admired the most. I did a layout of the two opening styles and did not think I was losing any width at the top that would matter with the roasters and pans we own. My opening is 19.5" at the bottom and that is plenty wide, and the first 2.5" is straight up anyway.

[tommo21]

Thanks JR, All good points there. I think it will be a decision based on aesthetics for me, i will have a look at some more photos and go from there. Obviously hitting that 63% number is important. So wherever the dome ends up i will adjust the arches to suit.
And i guess i can report that I have officially started on the oven 'build', just.
I have poured the footings for the hearth slab to bear upon. I have a slightly different set up to the plans, my oven slab will be supported on an existing retaining wall at the front and the new footing beam at the back.

[tommo21]

Another thing that i am wondering now, is, do the dome bricks need to be tapered on the sides as well as top and bottom? Or is it adequate to have large mortar joints at the outer dome?

The design dimensions i have agreed with myself on:

1. 40 inch floor (1020mm)
2. 19 inch dome height (480mm)
3. 19 inch opening width (480mm)
4. 12 inch opening height (300mm)

I have the hearth slab poured and is now curing.

I need to order some insulation and fire brick.

i am planning to install a heat break between the inner arch and the vent arch,to increase the oven efficiency. Would solid reds (clay bricks?) be an adequate choice for the vent arch?
Would the reds provide me any advantage apart from cost saving? Could i use them for the dome arch also?
I am thinking the reds might be harder and avoid chipped edges?

Thanks for all your help.

[deejayoh]

You taper the sides only, not the top or bottom. The reason for tapering the sides of the bricks is if you want to have a tight fit on the inside of the dome. If you don't want to taper the sides, you end up with little triangles on either side of the joint, not really a big deal - but not as aesthetically pleasing as if you taper the bricks.

You don't need to taper the top/bottom, because the joints there don't matter. At the front they will be tight (2 flat surfaces) and at the back, no one will ever see them.

If you are curious about the tapers, you can check out my spreadsheet in the tools & techniques forum. It calculates all angles for you based on inputting your dome dimensions.

[tommo21]

Thanks deejayoh,
I have studied the calculators and jigs, all very fine work, but i wasn't sure if anyone was cutting the large face. Thanks for confirming the norm.
I would like to eliminate the inverted vee and if i can find a sensible priced brick saw i will. brick saws here in Australia are about $1000!! i might be able to source a cheaper 'tile' saw and make it work.