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-   -   Base size and hearth to fit question (http://www.fornobravo.com/forum/f8/base-size-hearth-fit-question-4251.html)

Puy de Dome 06-09-2008 03:53 AM

Base size and hearth to fit question
 
Hi

I am reading page 13 of the Pompeii oven instructions - the dimensions.

I would really like to build the 42" oven, but, as you might have seen on my other thread, the base slab I poured was really designed for a barrel vaulted oven - which I have now decided against.

Here's a pic of the base. It measures 50" wide by 56" deep, by 6" in height.

[IMG]http://i194.photobucket.com/albums/z...t/IMGP1562.jpg[/IMG]


According to the info on page 13, the 42" oven needs a base of 69". Am I reading that correctly?

So I start out with an exterior dimension of 51", which exceeds my base, then by adding the insulation and other layers, end up at 69"?


If this is not going to work in my case, can I still maximise my oven internal diameter without compromising the thermal mass and the insultation? I do want a proper dome, not a gherkin shape.

Many thanks.

Puy de Dome 06-10-2008 12:07 AM

Re: Base size and hearth to fit question
 
Anyone? Can I put a domed oven on my slab that measures 50"x56"?

Can I just take however many firebricks out of the chains and maintain the correct dome shape and insulative properties? Please.

SpringJim 06-10-2008 03:38 AM

Re: Base size and hearth to fit question
 
I see no problem with putting your domed oven on that slab.

I even think that you can extend the insulating layer beyond the slab if you want or even put some cantelevered bricks to hold that light layer if you need some additional space. What is the insulation layer going to be? What is the enclosure or final structure going to be.

I take the plans as great guidelines but I'm comfortable with variations...I'm headed to pear/egg/ovoid shaped not quite gherkin

....but don't gherkins come in lots of shapes:eek: ?

enjoy the build:)

dmun 06-10-2008 05:31 AM

Re: Base size and hearth to fit question
 
I did a quick sketch of your slab size and 42 layout:

http://www.fornobravo.com/forum/phot...ovensketch.jpg

As you can see, your 42 oven dome fits perfectly on top of your slab, but there's not a quarter of an inch for insulation. The good news is that your heavy dome will be fully supported, but you will have to build outward to accommodate the insulation layer. You could cantelever out an enclosure using metal framing studs, supported by the notch on your stand, but that might look awkward. If it were me, I'd pour a little more concrete at the ground level, and build your exterior walls up from ground level, to give you the extra room you need. You obviously don't need to insulate your wood storage, but a few internal baffles will confine your insulation to the areas where you need it.

Dutchoven 06-10-2008 05:54 AM

Re: Base size and hearth to fit question
 
Great looking design sketch dmun. I have to start playing with sketchup again...too cool.
Puy
Looks like you already have some kind of walls along the side of your block walls...is this true? Let us know because there may be a way to incorporate that into the way you will insulate
Best
Dutch

Is that slab in your picture just your structural hearth slab? If so did you plan on some other insulation in that area? If you can, give us some specifics on how that was constructed, materials, etc.
Best
Dutch

Puy de Dome 06-10-2008 08:14 AM

Re: Base size and hearth to fit question
 
Yes, hi. The following thread has info and better pics on the slab:


http://www.fornobravo.com/forum/f9/w...area-4189.html

The design came from Rado Hand's website in Australia. So originally for a barrel vaulted oven.

The slab is six inches deep, by 50" wide and 56" deep (ie, front to back).

It has three pieces of mesh/rebar in it. I deviated from the original plan inso far as omitting the vermiculate insulation in the top of the slab.

You can see that to the sides of the slab are two brick walls. Below this, and only partly in view are two supporting 'legs' - in fact a double concrete block wall - waaaaay more than needed for the oven, but are needed to act as support for the wooden deck-like areas to the left and right.


HTH.

Many thanks.

Dutchoven 06-10-2008 08:34 AM

Re: Base size and hearth to fit question
 
Quote:

Originally Posted by Puy de Dome (Post 34701)
Yes, hi. The following thread has info and better pics on the slab:


http://www.fornobravo.com/forum/f9/w...area-4189.html

The design came from Rado Hand's website in Australia. So originally for a barrel vaulted oven.

The slab is six inches deep, by 50" wide and 56" deep (ie, front to back).

It has three pieces of mesh/rebar in it. I deviated from the original plan inso far as omitting the vermiculate insulation in the top of the slab.

You can see that to the sides of the slab are two brick walls. Below this, and only partly in view are two supporting 'legs' - in fact a double concrete block wall - waaaaay more than needed for the oven, but are needed to act as support for the wooden deck-like areas to the left and right.


HTH.

Many thanks.

OK Puy,

I am quite familiar with Rado's plans, the barrel vault that I built is for the most part directly from those. As you might already know, you will want to put some type of insulation layer on top of that slab. Otherwise your oven floor will not ever really stay hot enough. That slab will become a huge heat sink.

Since you have these side walls it might be possible to run a course of concrete blocks or bricks to bring you up to the height of your hearth slab and then either pour a wider insulation layer on top of that or use the more high tech calcium silicate insulation boards. I think you will be able to gain the extra space needed to insulate the dome as well. How do you plan on finishing the oven? Gabled house, igloo?
All the best!
Dutch
P.S. After looking at the other pics I feel you can definitely pick up the extra space you need and still preserve the exterior look of the oven. It will be a nice finished product and the more you insulate the oven, and I mean insulate it, the happier you will be when it comes to baking and pizza.

Puy de Dome 06-10-2008 08:59 AM

Re: Base size and hearth to fit question
 
Thanks Dutchoven

Glad you know of Rado's plans. I'm now planning on putting an igloo oven on my hearth. I hear whayou say about the insulation on the hearth.

The brick wall to the sides respresent where the outer wall on Rado' plans would have been. I guess I can build out wards to within a couple of inches of their outermost edge and this make room for the base of the igloo.

I found something quite useful here in the UK that I can use to clad that part of the oven base - they are called 'slips', and are think slivers (10mm/quarter inch thick) of brick.

I'm not set on the exterior shell of the igloo, but thought about usng half bricks, end-on, to match the existing walls. I somehow think that a plaster (you call it 'stucco' I think) then painted might look a bit odd. Maybe not.

Puy


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