My first attempt for 42" oven / changed to 36"

[George_M]

Re: My first attempt for 42" oven / changed to 36"

Hi,
Yes i mean zigzag pattern.I will use large size bricks and i will not have many edges,you are right.
Can i use something else except clay because i haven't it.
Maybe chamotte/cement in ratio of 10:1 or more?
Just a small amount of cement.

I plan to start the dome on the cooking floor.
So the cooking floor will extend outside the dome.

[Tonyp]

Re: My first attempt for 42" oven / changed to 36"

Hi George,

You mean the zigzag herringbone pattern? I think that is more so you don't have too many edges all in a line to catch the edge of a peel or pan or tool. If you are using those large size blocks I don't think you will have too many edges anyway. If you get them close to the same level it's not too big a deal if the edges line up and are perpendicular to the oven entrance.

The recommendation is to NOT stick the floor bricks to the insulation layer OR to each other. That will allow them to move slightly and if you ever need to replace one you can remove it easily. You can use a little dry clay/sand mix underneath the floor bricks to help level them though.

What you need to decide though is do you want to have the floor bricks extend underneath the dome bricks or remain within the inside of the oven. You do not need a gap between each floor brick. However, if you decide to have the floor bricks inside the dome then the recommendation is to leave a small 1/8" gap between the dome and the outer edge of the floor bricks, which will fill with ash.

There are pluses and minuses to each. It's easier to just lay down the floor bricks and rough cut the edges and build the dome on it. It's more work to fit the floor bricks within the dome. If you want to ever change a floor brick though it's harder if the dome is sitting on the outer edge of the brick.

[George_M]

Re: My first attempt for 42" oven / changed to 36"

Hi,
The rain continue and today, so time for questions for the next step

As for the cooking floor.
I saw many people who put the bricks like waves,but my question is for the distance between floor bricks.

1)My misgiving has to do about thermal dilation-contraction.If the bricks has no distance between them,i think that will destroy the floor.
So,need distance or not?


2)Also i saw that he didn't put cement between bricks,only at the bottom to stick on the perlcrete.Is it correct?

Thanks

[George_M]

Re: My first attempt for 42" oven / changed to 36"

Thanks again Tony!
I hope that tomorrow the weather will be better to start the frame.

[Tonyp]

Re: My first attempt for 42" oven / changed to 36"

Hi George,

Oh I see what you mean. So either the first or second method using half bricks you will still end up with a 4.3" thick wall. I built mine with the wide side down. I felt it was easier to cut the angle on the narrow side instead of the wide side and easier to mortar more on the wide surface. Even though you have to cut more angle because the brick is wider and the gap at the back bigger initially. Really up to you how you do it. But you will need a perlcrete width of at least 36" + 8.6 + 2(1" beyond each side) 46.6" so your 47" plan is good. I would go longer though front to back to factor in the entry area.

[George_M]

Re: My first attempt for 42" oven / changed to 36"

Sorry, my mistake.
I think that you mean for the first row of bricks because i saw many builders that the first row put the bricks at the thick edge.
But,yes i will build on the flat side (4.3")
For example this builder put the thick edge in the first row.
http://www.fornobravo.com/forum/atta...t-img_1933.jpg

Another builder put the flat side first
http://www.phone2forum.com/interface...GRnFw%3D%3D%0A

And some others put hole bricks with angle
http://www.fornobravo.com/forum/atta...6_172035up.jpg

I think that the first two methods is easier for me to start the oven because i have angle grinder to cut the bricks.
So giving angle with the grinder is not the easiest think.

But why starts the construction with 3 different methods?
And which is the easiest?

The hearth is almost 55 wide x 60 deep but i don't want to make more than 36".
I think is good size.

[Tonyp]

Re: My first attempt for 42" oven / changed to 36"

Yes,i understand now.
I will use half bricks but the thickness will be the same,6cm(2,3inch).
The lenght of the bricks will be the half.
Thanks Tony!

Hi George,

Your bricks are 8.5 x 4.3 x 2.3 and you are placing them on the narrow edge for a wall 2.3" thick? Most builders place them on the flat side so the oven wall would be the 4.3" measurement. You can use them on edge if you want. The oven will heat faster but not hold as much residual heat. It's probably also a bit less stable building with the bricks on edge.

Did you end up making the 55 wide x 60 deep hearth? If so you have plenty of room for the thicker 4" wall. You could probably bump the oven to 38" and still use a 4" thick wall on a 55" wide hearth.

[George_M]

Re: My first attempt for 42" oven / changed to 36"

Yes,i understand now.
I will use half bricks but the thickness will be the same,6cm(2,3inch).
The lenght of the bricks will be the half.
Thanks Tony!

[Tonyp]

Re: My first attempt for 42" oven / changed to 36"

Hi Tony,
Why you calculate 2x half brick size for the external size?

Hi George,

If you measure the outside diameter across the center you will pass through the insulation and brick twice. Once on each side of the circle. I am assuming you are using a half brick thickness for the wall of the dome? For purpose of calculating the width and length of the perlcrete you can remove the insulation thickness. Hope that clarifies!

[George_M]

Re: My first attempt for 42" oven / changed to 36"

The external size is cooking floor + 2x the wall thickness. Wall thickness is brick thickness + insulation layer. If you are planning to put a coating directly on the outside of the insulation you have to add that in to wall thickness also.

Your outside dimension, not including insulation, with a roughly 4.5" brick is 45" (36+9). So going 47" wide on the perlcrete will give an extra inch on each side.

Hi Tony,
Why you calculate 2x half brick size for the external size?

[Tonyp]

Re: My first attempt for 42" oven / changed to 36"

Hi Tony,
I plan to use ceramic blanket.

Also i plan to make the frame for the perlcrete 47x47inch (1,20mX1,20m).
I think the size is good enough
What do you think?

Hi George,

You want the Perlcrete to extend at least to outside of the dome brick. I would probably go about an 1" beyond the dome on each side and back. You could end the perlcrete at the outside front edge of the dome arch but I would probably extend the perlcrete under most of the entry as well.

Your outside dimension, not including insulation, with a roughly 4.5" brick is 45" (36+9). So going 47" wide on the perlcrete will give an extra inch on each side.

47" of depth will extend the perlcrete only an inch beyond the front of the dome arch. Those entry bricks close to the dome arch and oven floor will get pretty hot while in use and if there isn't much thermal break will suck heat out of the oven mass. So extending the perlcrete further under the entry bricks will help with heat loss to the concrete hearth underneath.

[George_M]

Re: My first attempt for 42" oven / changed to 36"

Hi Tony,
I plan to use ceramic blanket.

Also i plan to make the frame for the perlcrete 47x47inch (1,20mX1,20m).
I think the size is good enough
What do you think?

[Tonyp]

Re: My first attempt for 42" oven / changed to 36"

Hi George,

What are you planning to use for insulation outside? The type you use and how important it is for the oven to stay cool to the touch and hold heat will make a big difference on the thickness of your insulation.

I am using ceramic blanket and planning on at least 4"+, although a few snug spots it's more like 2.5-3". If you are not as concerned about the oven getting warm on the outside and holding heat for as long as possible then you don't need as much insulation.

The external size is cooking floor + 2x the wall thickness. Wall thickness is brick thickness + insulation layer. If you are planning to put a coating directly on the outside of the insulation you have to add that in to wall thickness also.

[George_M]

Re: My first attempt for 42" oven / changed to 36"

Due to bad weather conditions i stopped the activities for now.

As for the total external size is:
36" cooking floor + half bricks 4,3" + 6" insulation = 46,3" ???

My calculations is correct or i missed something?

Thanks for your replies!

[david s]

Re: My first attempt for 42" oven / changed to 36"

Thanks Tony!
Between the perlite insulation layer and oven floor must I put some material or I can build the oven floor on it?

The usual is to put down a layer of 50/50 sand, clay either wet or dry, as a leveller between the vermicrete and the floor bricks.