Corner Build Foundation Question

[ralogan55]

Let the games begin.....

After determining a corner build for the Pompeii is the best option for me I looked on pp. 17-18 of the Pompeii Oven Instructions regarding the foundation and am still a tad confused. None seem to equate to a 36" or 42" Pompeii oven that I read so much about.

If I subtract 9" from the exterior dimensions I come up with interior oven sizes of 26.5", 31.0", 34.5", and 40", respectively. I understand that the 36" oven isn't exactly 36" - more like 35.6" (or something like that, but not 34.5"). Or am I wrong?

Egalecki built a 36" on a 64"x64" corner build, but there doesn't seem to be much room left for an enclosure should I go that way.

I have enough room to build a foundation of 74" on the long sides and 51" on the short sides (plus the 45 degree foundation angle in front). That should be enough for a 36" Pompeii, but what about a 42"?

I tried laying it out on a grid as suggested, but there wasn't enough room for a 78" depth.

I don't see enough discussion (or I'm dizzy from all the reading) on the subject so I need some help.

Thanks.

[fxpose]

Re: Corner Build Foundation Question

I understand space is extremely limited in your situation but have you thought of just laying the hearth slab and simply building whatever size dome would fit within? That is the route I would take if I were faced with that situation, letting the limited space dictate the maximum size of my oven.

[ralogan55]

Re: Corner Build Foundation Question

I sure did and in absence of any better advice that's probably what I'll do.

I'm just under the impression that things come together easier with a 36" or 42" oven (ie, even number of bricks, material list is done already, etc.).

I'm sure I could figure things out with a 39" or 41" oven, but why make more work for myself unnecessarily.

Some things can be costly (time and money) to correct. Since there's a wealth of expertise out there I'm asking first. There's a name for the other kind of people (fool).

Thanks.

[Les]

Re: Corner Build Foundation Question

.

I have enough room to build a foundation of 74" on the long sides and 51" on the short sides (plus the 45 degree foundation angle in front). That should be enough for a 36" Pompeii, but what about a 42"?

I'm not quite visualizing your set up - can you post a rough sketch of your corner area?

Les...

[ralogan55]

Re: Corner Build Foundation Question

My jpeg photo files are too big and I can't attach an Excel file so I'm SOL for right now. Let me work on it. Thanks for the offer.

Rick

[Les]

Re: Corner Build Foundation Question

Do a crude sketch using paint - should come through for us to see.

[ralogan55]

Re: Corner Build Foundation Question

Wow, I didn't know I could cut-and-paste from Excel into Paint (duh!). I guess I learn more from FB than just oven stuff.

The first attachment is my layout that I built in Excel. It shows my foundation size, block layout, and rebar config. I have a foundation of 74" on the long legs and 51" on the short legs (plus the front angle) less 2" setback on all sides for the block.

The second is a new photo taken this morning of my oven site in the corner of my backyard.

I kinda over-excavated, but I have 6'5" to work with on the right long leg, but are using 6'2" and 8' at the top leg (and using 74" here also).

This corner isn't a 90 degree corner and the fence (at the left) diagonals pretty quickly inward and has created some problems in placing the foundation concrete forms.

Any comments or observations would be appreciated. Thanks.

Rick

[Les]

Re: Corner Build Foundation Question

It looks to me like you can build a 42 inch. You will need to do an igloo instead of an inclosure. You will also lose the prepping area in front of the entrance, but it seems like a small price to pay for the larger size.

The numbers I used are:

42 inch inside diameter
9 inches total brick width
6 inches of insulation (3 on a side)
2 inches for cladding (1 inch on a side)

Les...

[ralogan55]

Re: Corner Build Foundation Question

Thanks, Les.

I was just looking at gjbingham's corner build (which you "consulted" on) and learned some things (as always).

He had a 56"/40" +/- stand and ended-up with a 37" oven which created/required a cantelever in the front.

Your measurements from the last post seemed to be from side-to-side, which confirms my calcs (except for the cladding). But my bigger problem is overall length.

According to page 13 of the Pompeii Oven Instructions the all-in length of an enclosed 42" oven is 78". With a 70"/51" stand (and according to my calcs) I have 82.65" (diagonally) from the far corner (upper right) to the center of diagonal front (lower left). Shouldn't I have about 4.65" to spare (length-wise) with an enclosed 42" oven?

Geometry & Trig weren't my strong suits so I may be missing something here. I would prefer to have the option of an enclosed oven unless that's absolutely not possible.

What am I really gaining in having a 42" vs. a 36" oven (other than 6") from a practical standpoint?

Thanks again.

Rick

[dmun]

Re: Corner Build Foundation Question

Geometry & Trig weren't my strong suits so I may be missing something here. I would prefer to have the option of an enclosed oven unless that's absolutely not possible.

You can do an enclosed oven in the same footprint as a igloo if you get creative with your metal studding. You can skip the sill plate all around, and just secure it to the stand in the corners, and then tie it together higher up when the dome curves in.

[Les]

Re: Corner Build Foundation Question

Rick,

I didn't do any calc's either. I simply drew out your dimensions and placed a 59 inch circle in it. I had to place it all the way into the back corner to give you the distance you need for the entry. Pretty crude but it worked for me. Sometimes a picture is worth a thousand calc's. If you did do a cantilever in front - that would be a game changer. I don't see where you would have any issues at all. I think your biggest challenge is the set back from the fence. That may be a problem regarding code/neighbors.

[ralogan55]

Corner Build Foundation Question

Thanks for the help, Les. I've always been an admirer of your build and have copied all your photos to help in the process.

At the end of the day I think I'm gonna do what fxpose had suggested: build my 74" x 51" and then build the stand with a reasonable sized cantelever in the front to handle the biggest (not to exceed 42") WFO I can.

Once I get the stand built I'll know for sure what I can do. For right now, I need to focus on framing, rebaring, and pouring the foundation.

Thanks to all for your help. I'm sure I'll need more later.

Rick

[egalecki]

Re: Corner Build Foundation Question

Sorry, got here a little late! If I hadn't put so much extra vermicrete on the outside of my oven (there's probably 4 inches on top of the two layers of blanket), I'd have had room for an enclosure using the nifty steel studs. You would still have to use the blanket since the insulation would be insufficient on the sides otherwise, but you could fill the rest of the enclosure with loose vermiculite.

As far as 36 vs 42 goes, well, I used to think a bigger oven would have been better, but as I've used it more, really, I can't cook more than two pizzas at a time successfully anyway- and I could fit three in my 36. I just can't manage that many without burning them. And to tell the truth, I usually only do one at a time, since they go so fast! When I am baking lots of bread, I sometimes wish for more space, but I don't actually need it. What I need is to make smaller batches of bread.

The things you don't want to forget are:
-Your entryway needs to be wider at the front than where it hits the oven. It's really hard to get a door to work well if it's not tapered. See Ken's oven for a nice taper.
-No one will be looking inside your oven to see if all your joints are perfect and even and smooth. Trust me- it is NOT worth making yourself miserable to have an immaculate job. Good enough to stand up is just fine.
-If you do an igloo, caulk where your chimney meets your stucco- if you don't, it'll get wet when it rains, and that's BAD.
-Modern insulating materials rule! Yes, they cost money, but they do a better job in less space. As Dmun says "insulate, insulate, insulate".
-Oh, and don't forget to insulate underneath as well!!!!!
-have fun and enjoy the process as well as learning to cook in it!

[olddude]

Re: Corner Build Foundation Question

36" is = to about 7 sq feet
42" is = to about 9 sq feet
from what i can gather from reading of others is this 42 in oven not likely to fire for just a couple pizza's
takes more wood and longer to heat up
so i modified mine stood the edge cors on end to give me more room next to sides
but i'm building the 36
better to cook more often and have second tought about heating it up

[ralogan55]

Re: Corner Build Foundation Question

Well, I've got my excavation done (overexcavated) and my forms set. We need the rain in CA, but it's slowing me down. I have sandy clay soil (silica) and it takes forever to perc and dry out.

Next thing: compact soil, lay rock base, compact again, install vapor barrier, wire mesh, and rebar. Then look at it a long time. Rain coming on Monday (supposedly). Concrete on the Apr 24th. It'll take about .6 yards; the rest will go inside the garden/seat/retaining wall. I'm ordering a one yard in a pull-behind unit from the local equiment rental yard.

Is a 5 sack mix strong enough or should I get the 6 sack mix?