42" Pompeii at the Concrete Casa

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Slab: check. It was terribly anticlimactic, probably the first time I've been totally ready when the concrete truck pulled up. I helped my neighbor with his sidewalk, and had just enough to fill all the cells in the block wall and finish the top.

It was a great mix, 6.5 bag and I put a pound of glass fiber in it as well, whenever I am not cooking pizza that thing will double as a bomb shelter.

I feel like I cheated by not having the mixer and oodles of bags of concrete, but I am very glad it happened that way

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Quick materials question as I wait for my slab to cure...Insulfrax vs. Durablanket - are they comparable? Insulfrax seems to be at a much higher price point.

I've seen a lot of discussion on these but no definitive recommendations.

Thanks...

[dmun]

Re: 42" Pompeii at the Concrete Casa

Durablanket is a new name to me. Seems legitimate. Unifrax urges you to contact a product engineer by phone to determine the best of several products for your application, I'd recommend this.

[michaewa]

Re: 42" Pompeii at the Concrete Casa

It was suggested as an alternative by someone I was trading emails with at Armil, I'm doing a little research now to see how it stacks up.

[ThisOldGarageNJ]

Re: 42" Pompeii at the Concrete Casa

I've been to their website before,, I get nervous when they dont post any kind of pricing as to me that means they will charge you what they think you will pay.... Im curious to hear how you make out

Good Luck
Mark

[michaewa]

Re: 42" Pompeii at the Concrete Casa

I got the firebricks this week, my insulation board should arrive today as well.

This may be a dumb question, but as you lay out the oven floor, there is no need to cut the bricks where they hang out from under where the dome will be is there? It isn't entirely clear from the photos.

The only advantage I could see from trimming off the excess would be slightly less thermal mass as you were firing the oven.

Also, any suggested sizes for the landing for a 42" oven? I'm trying to determine just how far back the center of the dome should be from the front of the slab to be comfortable to use and provide enough working area in front of the oven.

Thanks!

[dmun]

Re: 42" Pompeii at the Concrete Casa

there is no need to cut the bricks where they hang out from under where the dome will be is there? It isn't entirely clear from the photos.

No need at all. I only trimmed bricks where I could get a clear half brick to use somewhere else. If you are going igloo, you may want a roughly round shape to conform to your dome, but otherwise, just build the dome on the floor.

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Thanks dmun for the confirmation. I've spent the last few minutes looking back at pictures and have noticed a lot of people building the floor inside of the soldier course rather than underneath it (so the walls sit on top of the floor).

I'm going to assume this is a matter of personal preference (and as you said a function of how you are going to finish the outside) and will not materially affect performance. Since I will be enclosing the whole thing I'm not going to be bothered by the bits hanging out - insulation board, floor brick edges, etc. Please let me know if I'm way off there...

Cheers!

[ThisOldGarageNJ]

Re: 42" Pompeii at the Concrete Casa

rather than underneath

I put my soldier course on the floor... No problems and the oven works great... I think it is a matter of preference... I also did it to save cutting

Cheers
Mark

[michaewa]

Re: 42" Pompeii at the Concrete Casa

I'm generating a lot of questions as I begin to lay the insulation down...

I got four sheets of insulation board to be on the safe side. That leaves me with almost enough to do a double layer, i.e. 4" of insulation below the firebricks. My question is regarding thermal engineering...assuming I did two layers would it be worthwhile to have the first layer of insulation cover maybe 80% of the area of the actual oven floor (say under the center of the oven), then have the 2nd layer (directly below the oven floor) be fully covered? I guess the alternative would be to piece the extra insulation board together in a skirt around the edge of the oven. I don't know if that extra 20% would cause enough thermal leaking to make it not worthwhile. I would fill in the 20% that I couldn't do with insulation with concrete blocks cut to 2" or maybe even just sand.

Secondly, any reason not to do brick shims on the outside of the dome rather than filling in the largish joints with mortar? I thought I could cut a handful of bricks into shims, put a little mortar top and bottom, and put them in the joint. I'm definitely not a mason, so that may be more trouble than it is worth.

Finally, I replied to the original poster about the Essential Tool but didn't get any response. I thought I'd check to see if there are any of those still floating around out there that I could woo away from someone temporarily in exchange for shipping costs, lavish praise, and maybe even some homebrew rather than building my own.

Cheers!

[ThisOldGarageNJ]

Re: 42" Pompeii at the Concrete Casa

maybe 80% of the area of the actual oven floor

my only concern here is that you would create hot areas on the other 20% of the oven floor "maybe" giving you an uneven heating in the oven.....

or maybe even just sand.

sand is not a good insulator....vermicrete would be much better

I thought I could cut a handful of bricks into shims,

dont see any reason why you couldnt do this if you wanted to... Especially if you have cut pieces left over..

Cheers
Mark

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Thanks to all for your input both in this thread as well as the rich archives. I've spent most of the day a bit paralyzed by all the options and questions but starting to get a better handle on the steps ahead.

One thing that I'm not completely clear on is the landing - mainly where most of you are measuring the beginning and end of the landing - e.g. interior wall of the oven, exterior wall extended, or some other point.

Perhaps the attached image will make it clear - this is what I'm thinking, anyway. Basically the landing will be two full bricks deep (18") measured from the inner wall of the oven, or 1.5 bricks deep (13.5") measured from where the extention of the exterior wall will be. I've got it spaced so the door opening will be 20" wide at the bottom, and flared out to 25" measuring from the inside of the landing bricks. If you can't read the tape, it measures about 17" from where the inner wall of the oven would be to the edge of the board.

The red lines on the brick are where I would notch the bricks to give myself a 1" reveal. If you extend that red line and assume that footprint is the actual first course of the vent, it would mean a half brick width (i.e. 1.25") which is probably a bit thin. In actuality I would probably go with a full brick from the outer wall on out, so that the red line extended would line up with the inside surface of the brick closest to the oven opening.

This 'feels' about right to me, but I want to make sure I'm not cutting things too close for my vent, etc. It also works well with the insulation board and will serve to minimize the cuts I need to make.

Any feedback or suggestions? I feel like I'm completely over analyzing this...

[ThisOldGarageNJ]

Re: 42" Pompeii at the Concrete Casa

Hi Mich,
My only concern, Your landing/tunnel may be too deep.. Suggestion ... Take a broom stick and pretend its a pizza peel, just make sure you can access all areas of your oven easily from thru the door. If you can , you should be fine. My landing/tunnel is only one brick deep.. I attached some pics from when I was building hoping they would explain it better

Cheers
mark

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Thanks Mark, that is very helpful.

I'm going with your vermicrete suggestion. I formed up a 2" deep square slightly bigger than my oven footprint today, and got a bag of vermiculite.

I cut my IB out and had one complete sheet left over. I'm going to center that roughly under the oven starting around where the door will be, and pour around it. I may end up with spots that heat up faster than others I suppose, but I'm ok with that.

Should have some pictures later today. I also borrowed my neighbor's tile saw so I'm going to cut the soldiers before I have to run all over and eat turkey for the next several days.

Is the best way to determine the angle for the top of the soldier course just to lay it out and back into the angle? I'm going to try to use 1/2 brick standing on end rather than a full brick, and I'm hoping I can get two soldiers out of each brick.

Cheers...

[michaewa]

Re: 42" Pompeii at the Concrete Casa

That vermicrete is odd stuff. I used the guide here and went 10:1, I hope it sets up. Worst case scenario I'll just leave the wood forms around the outside.