40" pompeii, first time builder

[totalnewbie]

Hey all,
On the sage advice of Utah, I am starting a thread on my upcoming build. For background, I don't really have masonry skills, though I've laid some tiles in bathrooms and done house renovation. I started off thinking I would build a sandcastle home-brew cast oven to keep things simple and affordable, but I decided that If I'm going to put in this much effort, I should build something that will last. We bought a house with a walled garden but no outdoor living or cooking space. East coast, so too hot in the summer and some snow in the winter.

I've read the Pompeii book a couple of times, and it does a great job of outlining options and trade-offs, and I'm hoping this group can bridge the gap with some real-world experience when the time comes to make to those decisions. I'm thinking 40" and I want to build in inches, not metric. Right now, there are a lot things I know from the book that I don't know how to answer yet. Depth of landing, should I overhang it, if I overhang it do I pour the hearth and the overhang landing the same time, what height do I use for the landing if I don't know my finish material yet, enclosure shape, dome height (is a low dome harder to build, can you tell when you cook?), I want to make real Naples pizza, do I shape the enclosure with chicken wire, rebar, or metal studs, how to cut the angles for the oven opening bricks, should I cut all those tapered bricks or use more mortar, where to buy my stuff, what is the best material for a spacer on the outer edge of the dome and vent, am I going to use the IT or a mold (foam, plywood, or sand), finish the plug or pour it in castable, landing material, make a door, find a chimney, which bricks should I buy so they last and don't spall, do I wrap the dome with aluminum foil before insulation to keep water out, do I install a metal rim around the oven floor to keep water out, is all sand the same. I'm sure there's more. The garden floor is brick. Do I have to take them up under the oven, or can I build the stand on top of them.

This is going to be fun! I know that I need to answer some of these questions before I even do the final sketch for the hearth and order my blocks!

This group is incredible. I don't think I would even think about doing something like this without all of you experienced and incredibly helpful builders.

Thanks for all the help so far, and in advance for what comes next.
Newbie.

[totalnewbie]

Hey all. I've found most of the materials locally (I'm leaning toward perlite because shipping costs for boards and blankets is really high to Virginia). I'm starting to plan out my timeline. It seems like one of the big time components is cutting firebricks in half. I bought the Harbor Freight 10" tile saw ($500).

Is there a best practice for doing this? I'm wondering if you can cut the brick at 1/3 depth (or even 1/4), and then hit it with a mallet and mason's chisel to break it in two to go faster. The cut edge faces outward, so you never see it. What do you think? Is score and break a potential "go faster" trick?

Thanks for the input.

[MarkJerling]

It depends very much on the bricks. Some bricks will break neatly along the cut line, others not. With the type of bricks I used, it did not work, but I know with some other bricks it might.

[UtahBeehiver]

Just remember it takes about twice the thickness of pcrete to equal CaSi and ceramic blanket. 5 to1 under floor and 8 or 10 to 1 on dome.

[mongota]

Is there a best practice for doing this? I'm wondering if you can cut the brick at 1/3 depth (or even 1/4), and then hit it with a mallet and mason's chisel to break it in two to go faster. The cut edge faces outward, so you never see it. What do you think? Is score and break a potential "go faster" trick?

Thanks for the input.

Some advice. This will a build full of questions and head scratching. You'll spend some extra money in one place and save some in another. You'll waste time trying to figure out a slick method to save time, or you can save time by just getting to work.

Heck, I almost gave myself a bald spot with all the head scratching I did.

You can score and snap most firebrick. And you can waste a few brick in the process. You can tap a break line with a brick chisel and tap tap tap tap until it snaps. You can partially cut a line and tap tap tap to break it. You can rent a splitter, manual or hydraulic. Or you can just cut the darn things through with your wet saw, getting a fast and clean cut, all while letting the cutting diamonds do the work. I recommend the latter. Wet saw, diamond blade, full cuts. Just get it done.

You'll have roughly 250-275 brick in your oven. Give or take depending on design. Some full brick on the floor. Some cut in half for the first few course, some cut into thirds for the upper courses. Cutting with a wet saw and a decent diamond blade, the cutting goes fast. They go accurate. And they mortar together easier. The cutting or the brick is not what will slow you down.

If you're building a house enclosure then loose fill insulation can work. I did a stone dome so I used 4" of board under the floor and 4" of blanket over the top of the dome to maintain the dome shape.

I used some graph paper, a pencil, and plenty of eraser to lay out my design. It helped me think through the dimensions, the proportion, and the clearances. Doing that work answered a lot of my questions.

The height of my oven floor is maybe an inch below elbow height. It's a comfortable height for me when wielding a peel. A deep landing and landing tunnel may limit your side-to-side action when working within the oven with a long-handled tool.

Tapering brick. You don't need to taper then entire side of each brick. I do recommend at least tapering the first inch or so of each side, so you'll have thinner mortar joints on the inside face of the dome.

You're in the planing and thinking phase. Come up with a plan and be able to explain why you want things the way you want them. Be ready to shift expectations as your build progresses. Some things that were near and dear during the design phase may not be important later on. Some ideas you might not have thought of, you may want to incorporate as your build evolves in front of you. Some build to the plan, some shift gears and change things up. Nothing wrong with either path.

Welcome to the forum!
Best, Mongo

[totalnewbie]

All great input. Thanks. I think I'm good on the perlite thickness and mix with Portland cement. If anyone knows a good source for ceramic blanket and calsil board in the mid-Atlantic, let me know. Distribution International was pretty challenging to work with and they didn't have any inventory near me, so shipping put it out of reach. You ask masonry dealers if they have bulk perlite and they look at you like you have two heads. Perlite from Amazon looks best.

Mongo! Thanks for the response. I can see wasting time and bricks trying to save time and money! haha. Clean cuts it is.

Has anyone calculated bricks/per minute, or the total time to cut 250 bricks? :-)

[rsandler]

Agricultural suppliers may have perlite for cheaper than Amazon; trick of course is finding one that will sell to individuals (unless you know a friend with a farm who can lend you their FEIN). Near me there was an ag distributor that had 4cuft bags of perlite for $15, but insisted they were wholesale only. To get loose perlite for my enclosure I ended up cleaning out an Ace Hardware an hour's drive away that happened to be down the road from a perlite factory and had the big bags for $18.

For the CF blanket at least, I'm not sure if I can find them again, but on my first oven I managed to get my blanket from an HVAC contractor supply place in DC; you might call around to HVAC supply places near you.

To reduce brick cuts, one actually-useful time-saving method is to use an angled fence/jig, which lets you get two tapered half-bricks out of one full-brick with three cuts, instead of 5. See http://www.fornobravo.com/forum/f28/...ble-16780.html for the original idea, also my simpler version that relies on tilting the head of the saw instead of the jig table: https://community.fornobravo.com/for...697#post455697. But note that depending on your level of perfectionism, you'll end up having to do a bunch of additional cuts regardless of your method, when the angle you thought was right for the whole course ends up not working for a particular brick. YMMV.

[totalnewbie]

I keep doing research off and on for a late winter, early spring build. Thanks to everyone who has made helpful comments and sent messages.

I'm all in for a true Naples oven. Tall first course soldiers and a low, aggressive dome. So lots of outward thrust, and need for some buttressing? How do you do that buttressing? The Scott oven uses a massive concrete shell, that won't work here. Any input would be appreciated, and links to oven builds in this forum where members have already done this would be incredibly helpful! There are images on the web with (mostly Italian builders) doing this, but I can't find any real instructions.

Also. I have a red clay brick terrace I'm taking up and I'm considering using the bricks for the dome (not the floor of course). They're real red clay from the 1980/90s (probably). They're in nice shape with little wear and tear. Alan Scott said you would build the dome using red clay if budget was an issue.

What do you think? Would that be OK?? It's a hobby oven (not a restaurant) with weekend cooking.

Happy holidays, all.

[MarkJerling]

As for thrust, yes you'll need some way to stop that flat dome from spreading. There are various solutions and all work to some extent. Steel rings, chain, etc have been tried. I think brick buttresses would be my go-to if I were to do it. Of course, the tricky part is to know how much buttressing you'll need. I have no idea.

Clay bricks can work, but not all brick is capable of handling the heat cycles. One idea I have seen done is to make the bottom two thirds of the dome in regular brick and then change to firebrick as the top of the oven is, of course, the hottest when you're cooking. It may be a good idea to see how some of those clay bricks behave if you repeatedly heat and cool them to 600degC.

[totalnewbie]

Thanks Mark. I can't really work out the best way to buttress the solider course. I can't see buttressing the dome with more brick or concrete -- that would make the dome mass too thick. I don't have metal skills or access to a shop. I also can't see a layer of vermiculite concrete providing must outward support. Maybe I build a simple hemisphere dome.

On a real practical note, I am struggling finding materials. If anyone has built in Northern VA and knows sources, I would appreciate it.

Last, can someone point me to a good posting on the type of sand I'm looking for.

Thanks all!

[totalnewbie]

Sorry to be asking so many questions.

Is there a good shopping list link someone can forward? Or a Google doc spreadsheet? I'm going to build either a 90cm/36" or 100cm/40" oven and I need to start getting serious about buying the right quantities of everything, so I don't have to keep re-ordering (I do that too often) or have a lot of material lying around at the end.

Thanks again.

[rsandler]

There is a materials list in the Pompeii oven plans (the appendix toward the end). The deejayoh's dome calculator may also be useful for the number of firebricks: https://community.fornobravo.com/fil...etch?id=319989 .

As far as sand, you want a relatively fine sand, as it will be easier to work with, and easier to get tight joints. I used a 30 mesh "industrial sand" sold in bags from my local big box store on my second oven, and it was fine. From my research, a finer sand would have been nice, but I couldn't lay hands on any. A "mason's sand" might fit the bill.

I built my first oven in DC, and got my bricks and much of the other masonry materials (sand, lime, bagged fireclay etc.) from Ernest Maier in Bladensburg, which should be a reasonable drive for you from NoVa; they also have locations in Gaithersburg and Charlottesville.

[totalnewbie]

Thanks rsandler. I wrote to Ernest Maier and will call if they don't respond. It's too bad there isn't a company out there who specializes in pizza oven materials -- blankets, Calsil boards, etc. Oh well. haha.

Here's an idea. Let's say I want to do the first course as a soldier, and then build a dome lower than 18" for a 36" wide oven. Not a hemisphere. I would like to balance having a lower dome, without running the risk of getting cracks from the lateral thrust of the dome against the soldier course with buttressing.

How high would you all recommend I go to balance better pizza cooking with structural integrity.

Last thing. I have a pile of free red clay splits that I am planning on using for the dome. Looking that pictures of traditional Naples oven builds, they use very narrow bricks. I don't think the splits will work well on a basic hemisphere dome (36" wide and 18" tall).

What do you think?

[david s]

Firstly, our hosts who kindly supply this forum for home builders, also sell all kinds of oven building materials and could probably advise you of alternatives if they’re not in your area.
Regarding the style of oven you want, ie vertical walls at the
perimeter and a low dome, it is not recommended for brick builds unless the walls are either buttressed or steel braced. This is because the mortar joints are under significant stress from different thermal expansion rates. Cast ovens by contrast however, get away with this form even though they’re usually thinner, by being cast in sections. Most cast ovens are of this form. So if it is this style you’re after, you might be better off going with a cast “off the shelf” or self built oven rather than do buttressing or steel bracing.

[totalnewbie]

Hi David,

You have a lot of experience. What does buttressing mean in this case? I've seen the Scott oven, which is encased with inches of concrete. That's buttressing. You can't, or at least don't want to do that with a dome oven. The 4.5" brick is basically already too thick for a typical backyard pizza oven doing a mix of pizza, roasts, fish, some bread, paella, etc.

Other than a metal band -- either around the dome itself or the soldiers, how do you "buttress"?

A mid-size kit is around $4,000 delivered to my region. I'm trying to avoid that.