Hearth Design Philosophy

[C5dad]

Re: Hearth Design Philosophy

Hi,

Looking to get some advice on the Hearth design in particular the insulation medium. I have purchased Vermiculite to blend at the suggested ratio of 5:1 with portland cement. Is the insulation cement strong enough to place the floor and dome directly on top of or is there an extra layer required to provide stiffness?

Yes, it is more than strong enough to support your dome. You do not want your dome on up insulated material as the heat will get "sucked" out -that is a highly technical term ya know.

Chris

[C5dad]

Re: Hearth Design Philosophy

Someone has said have the floor 'floating' what exactly does that mean? I was intending to bed mine down using a quite wet mix of homebrew
( i intend to have my floor inside the soldier first chain).

A floating floor is free to move with heating and cooling. Please do not bed your bricks and make sure there is a gap between the floor and dome (about the thickness of corrugated cardboard) to allow expansion of the floor outward without damaging the dome.

[Georgel]

Re: Hearth Design Philosophy

Door shape: Is there and advantage of the rounded doors? My house has straight lines and I am thinking of a rectangle door. Is this going to be a problem? 47 inch oven with16 inch dome height and 10 inch high by 20 inch door.

[Aquaponicsguru]

Re: Hearth Design Philosophy

I have seen glass bottles with perlite/vermiculite used for cob type pizza ovens. Anyone have any opinions on using glass bottles with a p/vcrete mix?

[narcosi]

Re: Hearth Design Philosophy

Hi AT,

Thanks for the info. Maybe I am using different terminology, being from the UK and all that.....I have attached a quick diagram of my proposed construction - please excuse lack of scale or detail as I am still earning SketchUp for this project....



I hope this all makes sense. The "Thermalite" blocks are lightweight, insulating concrete blocks that are very common here. The Ceramic Fibre insulating board is what I think you all call "FB Board". Damp proofing membrane is a polythene sheet that will go under the base slab itself - I would also use another layer of DPM after the first ocurse of concrete blocks in the support walls.

Cheers,

Alasdair

Did you ever build this?

Im just starting out in the UK and have created this topic where i could do with advice: https://community.fornobravo.com/for...-oven-build-uk

thanks

[narcosi]

Wow - this is a really useful thread, thanks everyone who has posted.

My plan is: https://community.fornobravo.com/for...-oven-build-uk

100mm (4") reinforced base
50mm (2") FB (should i double this???)
I too was planning fire bricks on their side for extra mass (is this a waste?)
I will then be building the brick walls on the FB

Just read about leaving a small gap around the floor and not setting floor bricks - thanks (wont this fill with ash etc? / do you clean it?)
I assume the walls however are fully set with oven cement?

I have a few questions on my thread which i am looking for advice on so please have a look for me.

with a plan for staight side walls would you use blanket down to your FB base of even do vertical FB up the sides?

thanks all!

[narcosi]

Re: Hearth Design Philosophy

Here is a drawing of what I did on mine:
It's a 42" oven, the concrete block base I did is 6 1/2' feet deep by about 6' wide. The width seemed about right for any 42" oven using glass fiber insulation (I used 3 layers of 'FB blanket') and I have a steel framed structure beyond that. I imagine if you do an igloo style (stucco or rendered exterior) it would be about the same.

I also have a row of concrete block thru the middle of the base stand to cut the 'wood' storage under it in half. This whole design of mine may have little to do with your design but I hope the oven dimensions help you out.



this is what it looks like:

Great post and diagram - thanks
I dont see a thermal break in your oven floor into your vent space - is this ok? struggling with the whole thermal break thing
it does look from your diagram that you planned one in the walls - or am i miss reading it?

loads more questions here: https://community.fornobravo.com/for...-oven-build-uk

thanks

J