Double Brick Oven?

[sellingforaliving]

Good evening. I am putting plans together and hope to build a wood fired oven this summer. As I live in a cold climate I was wondering about cladding the exterior of a brick over with a second layer of bricks. The reason I ask is I recently took apart a old fireplace and noticed that it was constructed in this way. They had the fire bricks next to the metal fire box and then a layer of standard bricks on the outside of that. I have looked around online and don't see anybody building ovens this way. We live in area where it gets cold (-40C) in the winter and I would like to be able to use the oven year around. I thought that using a building technique like this might keep the oven warmer for a longer period of time. Thanks for the help.

[dakzaag]

I would suggest that you look a little closer at the builds online. Most of them are indeed some form of enclosure surrounding the actual oven. The main detail that determines how long an oven remains warm is the amount of insulation that surrounds the brick of the oven chamber. The more insulation, the longer it stays warm no matter what your climate is on the outside. As you look around at other builds, notice how much insulation and what type they put under the oven and then what they put around the outside of the dome as well. 2-4 inches of high quality insulation below the floor is recommended and the perhaps a minimum of 4 inches around the walls and dome is a good start. If you build an enclosure around the outside of the whole oven, then you can fill the area between the two walls completely up with loose fill insulation such as perlite or vermiculite which is a good insulation and relatively cheap.
Good luck with your build and keep us posted on your progress.

[RandyJ]

I responded to your question in another place too, but I will here too. I live in mn so it gets pretty cold here too. I used 4" of ceramic board under the oven and 3 " of ceramic blanket over the top of the dome. Then I also filled my enclosure with vermiculite. I also built a door with 4"of ceramic board in it. With temps at 0 or below I have seen up to 10 days before I am under 100F. So I would say you need to insulate as much as you can afford. It does make a difference.

Randy

[llamabucket]

I would suggest that you look a little closer at the builds online. Most of them are indeed some form of enclosure surrounding the actual oven. The main detail that determines how long an oven remains warm is the amount of insulation that surrounds the brick of the oven chamber. The more insulation, the longer it stays warm no matter what your climate is on the outside. As you look around at other builds, notice how much insulation and what type they put under the oven and then what they put around the outside of the dome as well. 2-4 inches of high quality insulation below the floor is recommended and the perhaps a minimum of 4 inches around the walls and dome is a good start. If you build an enclosure around the outside of the whole oven, then you can fill the area between the two walls completely up with loose fill insulation such as perlite or vermiculite which is a good insulation and relatively cheap.
Good luck with your build and keep us posted on your progress.

Hey dakzaag! If you don't mind me asking, is it absolutely crucial for the dome and walls of the oven to be insulated? We're in the process of making a simple oven and we just poured 4" of perlcrete under the floor, but we're having various issues with figuring out how to insulate the top of the oven (it'll be a simple freestanding barrel vault oven). We were initially hoping to get away with just making the inside with firebrick and then surrounding it with regular red bricks. We only want to cook pizza and don't need the oven to stay warm for days.

[david s]

Sorry to jump in here, but that is not a good idea. If you lay a second layer of brick against the first one it will suck the heat out of the first layer causing slower heat up, grater fuel consumption and faster heat loss as the heat in the outside layer is in ambient air and you lose it to the cooler atmosphere. You really want to hold the heat in the inner layer, 4" thick walls is plenty for retained heat cooking.