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If you do 2-1/2 inch of firebrick, 1/2" of cladding should be adequate. It is going to crack, but it is not visible and should remain structural as it pertains to the minimal thrust of the of oven.
 

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Use the scratch refractory mortar for the cladding. I have made cubes and tested them in both the oven and bonfires, they do just fine. For laying the brick, however, Heatstop is worth the money. You can do 4" vermi/perlcrete then stucco over that for an igloo shape or as a monocoque shell if you do not want the extra cladding on the oven itself.

Some reading I have been doing leads me to believe that there has been a misunderstanding at what temperature portland cement reverts to it's constituent parts. I have had portland plant lab engineers tell me "500 degrees" is when portland cement begins to fail, but I did not clarify centigrade or Fahrenheit. Some of the recent articles I have read give the number as 500 centigrade.
I would like to see anything you have that shows anything different than 500f...it's always what I went on, and was told by a couple refractory engineers. But that doesn't mean their word is law, I just haven't seen a lot of trust put in portland for high temp applications...ones that are higher than wood ovens.

Sean, don't forget reinforcement in the cladding, otherwise it's just a parge and won't do much after cracking.
 

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http://www.sciencedirect.com/science/article/pii/S1044580314000643

http://www.scielo.br/scielo.php?pid=S1516-14392002000300014&script=sci_arttext

http://www.researchgate.net/publica...Thermal_Degradation_of_Cement-based_Materials

None of these specifically address our application, but since they are dealing with portland at high temps, some things can be inferred, one of which is that portland does not significantly degrade at 500 degrees Fahrenheit. Part of the issue is the aggregate used; it can cause degredation.
 

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I build my dome with the arched bricks. Then put 1x2 welded wire fence over the whole thing. Next came an inch or so of the cement fire clay mixture. I have no idea how it works out. It is under the perlite insulation and I can't see it. The dome is still OK.

One mistake I made was not to put a moisture break between the foundation and the brick work or the stucco rear. Now I have spaulding at the bottom with the freeze thaw cycles. But only on the stucco. Not the bricks yet.

Just put a layer of vycore at the bottom and build the stucco or bricks above. Or there may be some better way with edge screeds, weep holes and the like. Just remember...done is right!
 

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Discussion Starter · #26 ·
looks good Tscar. got the insulating pad poured last week. Was waiting on some perlite to come in because it's half the price of vermiculite. Finally went in to see if it's ever coming in and the owner says he never put in an order for perlite in the last 5 years so I have NO idea what his staff is smoking. Oh well, poured now.

Got the floor done today and the first course of the walls, haven't seen the camera in a couple weeks so you guys who like pics will have to wait.

Next question. 9" walls or 11.25? the arch will have a rise of 8" most likely. Is there a major benefit or disadvantage to either? With the 1/2 dome in the back the higher wall will give a little more room in the rear for roasts but really not many roasts i cook are even 9" in height. A ham would be but it could fit easily in the barrel part of the oven me thinks
 

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Yeah get it built and send me a price, I'll save my pennies for next year
 

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Discussion Starter · #39 ·
Walls are built and centre is ready for the barrel, but I'll have to do the half dome first. My decision to go with 3" thick units was a huge mistake. So much cutting and I hate cutting. Oh and i got my opening down to 17.25"

I've finally found a camera but this one won't recognize the USB so I could take pics but they are on the camera and I have no idea how to get them on the computer. If I don't find one of the good cameras soon I'll have to buy a new one
 

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I've finally found a camera but this one won't recognize the USB so I could take pics but they are on the camera and I have no idea how to get them on the computer. If I don't find one of the good cameras soon I'll have to buy a new one
Take the card out of the camera and put it directly in your computer (if it has a card slot), or get a USB card adapter for your computer.
 
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