42" Pompeii in Eastern NC

[Gulf]

On that note, any suggestions on the first course? I'd like to keep it a true half-spherical dome, so am planning on using 1/2 size bricks, standing upright, instead of starting with full brick height. I haven't decided on 'solider' or 'sailor' though. My understanding is that they're standing the same vertically, but rotated 90 degrees depending on the type I lay. I'm leaning towards the sailor course, with the wider side of the brick facing the interior of the oven. Are there any pitfalls I need to be aware of?

I am afraid that you have been a little misled somewhere about soldier and sailor courses. However, if you want to have a "true half-spherical dome" (hemispherical), my advice is to lay the first course just like all the rest. It is a stronger bond and it will work better with your IT, without having to adjust.

[SableSprings]

Hi Caliea! I'm one of the folks that just used no angle/no bevel on my build--just cut 'em in half (until I got to the last two rows where I did have to cut a few angles). As JR noted, that method takes the most mortar...but the mortar is almost all on the outside and is hidden by your insulation & primary enclosure. I have read on the forum where builders have used the dry saw method. It works, but produces HUGE amounts of dust...definitely requires a good quality dust mask. Most folks either borrow or buy a 10 or 12 inch wet saw to do the cuts. I'm pretty sure there was one build where all the bricks were simply cut in half with a brick chisel (no angles, no bevels, and a learning curve I'm sure ). Since you've got another builder nearby, you might see if you can pick-up a wet saw from Harbor Freight and split the cost & use. Also, if you have any builder friends or contacts it would be worth checking with them. I borrowed a 12" wet saw from a retired contractor down the road with the promise of delivered fresh bread...after 7 years, I still deliver them a "thank you" loaf every week I bake.

I'm really surprised that getting the hydrated lime is a problem...it's available through our (Oregon) Home Depot & Lowes. It may simply be a matter of local terminology or talking to a local masonry worker. Being able to make and use homebrew mortar would be a lot less expensive than the HeatStop (which I also used -$$$$ ).

Don't forget that it will be to your advantage to put in a moisture barrier between the top slab and the hearth insulation board. Also, if you'll be baking bread, you'll probably end up getting a insulated (firing/holding) door along with a lighter (cooking/working) door. Incorporating a thermal break will also help with the heat leakage.

I've used our oven primarily for breads. I normally bake 15-20 loaves on a single firing and have done up to 30. My insulation base was only 4" of 5:1 perlite:cement and I've got about 8" of 8:1 perlite covering the dome. With my marginal insulation, I certainly do not have great, long term heat retention...and I really wished I'd sprung for the ceramic board underneath, but seven years ago it just wasn't in the budget. I've been very happy with the Pompeii oven for my bread and the 2.5" thickness of hearth has worked well baking (primarily baguettes at 575-585F -- takes about 15 min per load).

The one problem I have with bread in my oven is loading. The door width and round floor footprint make "fitting" the loaves into the oven a little difficult. I have settled into baking 5-10 loaves at a time simply because getting to the back loaves (over the front loaves) is a bit challenging. That said, the range of being able to cook a 25# whole turkey or a full sheet pan of biscotti (as well as pizza) is fabulous.

Sorry to be late to the party (and to ramble on with this post...), but I'm looking forward to watching your build progress and hope my input has some value for you.

[Caliea]

Just answered one of my questions: the wet tile saw is too small (not enough clearance on the moving bed to the engine housing) to cut through a brick. Takes 4 cuts to score it enough to snap a brick in half. Not ideal for precision bevelling.

So... can I cut them dry?

[Caliea]

I have a saw question. I'm in the unique position of having too many options. I have a wet tile saw (7" blade), a dry chop saw (14"), and a dry 10" compound miter chop saw.

Which will be the best for bevelling firebricks?

And as a followup - should I use a.metal masonry blade with a continuous rim or a fiberglass abrasive blade?

[Caliea]

Thanks Utah. I was having a hard time finding distributors - didn't know the proper search terms apparently I have found a Distribution International about 3 hours from me and they've been helpful.

I have ordered the insulating board for the base. Ended up going with just 2" of board, which is minimal, but within the budget right now. I plan on working up a brick jig for my saw this weekend, and getting the hearth bricks cut, and if I'm lucky and have some time, I'm hoping we'll get the first course of bricks cut and dry fit for the dome.

On that note, any suggestions on the first course? I'd like to keep it a true half-spherical dome, so am planning on using 1/2 size bricks, standing upright, instead of starting with full brick height. I haven't decided on 'solider' or 'sailor' though. My understanding is that they're standing the same vertically, but rotated 90 degrees depending on the type I lay. I'm leaning towards the sailor course, with the wider side of the brick facing the interior of the oven. Are there any pitfalls I need to be aware of?

We tore apart the slab form last night, and were pleased with the settling/packing we got around the edges, just by using a rubber mallet and lots of tapping while the concrete was wet. Not many 'bug holes'. I know it doesn't particularly matter on this slab, as it will be hidden, but we wanted some practice for when we pour concrete countertops for the project.

Hopefully I'll have some exciting pictures to post this weekend! *fingers crossed*

[UtahBeehiver]

With some effective layout you can get by with 3.5 panels per layer or 7 total. There are other brands of insulating board, IE Thermal Gold 12, Insblok 19. Local refractory distributors will carry these or something equivalent. Some national suppliers are Distribution International or Harbison Walker, most likely one of these near you. You could go with a 8 to 1 perlite or vermucilte/cement insulating base. According to a chart I have from David S. a 8 to 1 ration has a thermal conductivity (K) of 0.60+/- Thermal Gold 12 is 0.55 at 700 F..Just depends on the budget.

[Caliea]

I need advice on the insulating board under the hearth bricks.

I was researching the FornoBravo insulating board (36"x24"x2"), and from what I can gather, I'll need 8 of the 2 " boards in order to get a 4" insulating layer. Buying from the website, that's $570, not including shipping. I've gotta admit - that hurt my feelings.

(1) Am I estimating incorrectly? I am planning on a 42" oven, adding in the 4.5" of 1/2 bricks for oven walls, it gives me approx. 51" across that I need to cover, and the front-to-back measurement would be that 51" plus another foot or so for the vent/2nd arch area. That makes it 4 panels per 2" layer, which means I need 8 panels...?

(2) Is there another option that is more cost efficient? Something I can add under a single layer of the FB Board that might not cost so much? I understand that this is a critical step, but when I figure the cost of the blankets for the top, and this board underneath, I'm at almost $1000! Makes my pocketbook wince, and not sure I can spin and polish that enough to get by my husband without some major groveling.

[Caliea]

Hi Ron,
I'm near Washington, so I've gotten my firebricks from Adams Products in Greenville. I also got some Firebrick mortar from them - they can get Heatstop 50, but it's special order and expensive. I've looked at the firebrick mortar reviews on here, and it seems acceptable, so I think I'm going to proceed with it.

Good luck with your build! Nice to know someone in the "neighborhood" that's facing the same challenges as me

[Ron-NC]

Hi, I am also building an oven (barrel) in Eastern NC - an Hour south of Norfolk. I am having great difficulty locating Hydrated lime and insulating bricks without spending a fortune for shipping. May I ask where you are sourcing your refractory items? Thanks

[Caliea]

We formed the shape and poured the slab today! That little sentence is so deceptive. It's hard work mixing all that concrete by hand!
I'm looking forward to getting started on the fun process of seeing an oven take shape!

[Caliea]

Spectacular! Thanks for the visuals - those help a ton!

I'm hoping to get the hearth slab poured this weekend, and then I'll be on to the fun stuff!

[JRPizza]

Here is a picture of a beveled only brick, sitting upside down on my low budget angle cutting table. There are lots of designs for more elaborate cutting jigs, but I just shimmed the 2X6 to get the angle I needed and cut my bricks. Of course I did say my setup was not too precise. At the bottom of the dome the bevels are none to slight, but get progressively larger as you approach the top of the dome.

[UtahBeehiver]

See if this helps. In this pic angle aka taper. I was one who did full taper and bevel just to say I did it, but I tell builder now, like JR says, just focus on the inside joints of the build and just do a bevel near the inside dome face of the brick and let mortar fill in the backside and sides, mortar is your friend.

[Caliea]

Thanks Utah for the link to the calculator. I'm going over while trying to absorb the info so I can visualize better.

JRPizza - thanks for the clarification on the methods of construction. One piece of terminology I am having trouble with: let's say the end of the brick that faces inside the oven is side A. Would I bevel the 2 sides perpendicular to A and touching the other bricks in the same course? Or all 4 sides connected to side A are beveled?

[JRPizza]

Caliea, remember that there are three ways to cut the bricks for your dome (at least I can only remember 3) - The easiest is just cutting bricks in half (will leave an inverted vee of mortar inside the oven and use the most mortar), second easiest (in my opinion) is cutting the bricks in half and beveling the sides (no vee, slightly less mortar, more complicated cuts), and lastly cutting, beveling, and tapering (no internal vee, smaller external gaps). I chose to bevel only, as it eliminates most of the mortar that would be exposed to flame in the oven (except for the arch), because several of the builders in the "what would you change" thread linked below said they would only bevel, and lastly because with the bevel only it seemed easier to get brick on brick edge contact on the inner surface of the oven. Lots of folks go the taper and bevel route, but if you are looking to minimize the cutting you might want to look into bevel only.
PS, I also used DJ's spread sheet to get my bevel angles and it got me very close. My beveling setup was not too precise though, so I used the spread sheet as a guide, I only had to bevel two bricks and place them in position to see if there were any adjustments needed. If there was I just kissed them with the saw and cut the rest of the row with the adjusted setup.
We are all looking forward to following your build.