Insulation question

[melvynhoare]

I am building a barrel oven and have a question on insulation, I am planning to place 3 inches of ceramic blanket followed by three inches of vermiculite and Portland cladding 6 to 1 mix. I will mainly be cooking pizza and tapas in this oven so with that in mind will I need first to put on the concerete cladding before any insulation, help!

[dmun]

Re: Insulation question

I'm afraid I don't understand your question. What do you need help with?

[Mojoe]

Re: Insulation question

The concrete cladding used in barrel ovens is not only for additional mass but also to strengthen the arches. The cladding you describe is more of an insulation mix not a structural mix, a 6-1 mix may be too weak.

[melvynhoare]

Re: Insulation question

I have three inches of buttressing on the sides and 4 inches at the rear, the arches are made with shapped bricks so will I need the cladding on the top to add strenght to the arches, or will it be OK just to add the insulation, thanks for the replys so far.

[Mojoe]

Re: Insulation question

I understand your logic in this hybrid build but I haven't read anywhere of a similiar build, not to say it hasn't been done. With no proven plans at hand, ultimately the decision is your to make as to the structural integrity of your oven. I will say that my main concerns would be the area where the arches meet the soldiers, where the arch meets the back, and the transition down from the front arch to the door. If you feel there are no structural issues then you could follow typical dome construction... blankets then cladding.

[melvynhoare]

Re: Insulation question

Any barrel oven builders out there who have completed a simular project, any advice would be welcome. I am not sure if I require more cladding. Would there be any benefit from putting blanket first then vermiculite or should I lust keep to the plans and put concerete cladding then blanket. I am in your hands.

[DrakeRemoray]

Re: Insulation question

Could you post some pictures? In general for tapas and pizza, you will want to keep your mass lower, so if it is structurally sound, I would not add any extra, just go with the blanket...

[CanuckJim]

Re: Insulation question

I've built a barrel vault Alan Scott type oven. It was intended for multiple bread bakes, so there are six-plus inches of refractory concrete cladding over the dome, then insulation. If you're not looking for multiple bakes, you might want to add about an inch or so of refractory concrete to the exterior of the dome before insulating. That would give you some added mass and structural integrity.

Jim

[melvynhoare]

Re: Insulation question

I have attached some pictures of my oven and progress made so far. If I can I would like to add blanket then 3 inches of vermiculite, if not I may go for option 2 which is an inch of cladding then insulation.

Please comment and give advice, and thanks for your input so far.

[Mojoe]

Re: Insulation question

I would not rely on that thin bead of concrete on your transition bricks (angling downward towards the door) in the second picture nor would I rely on the wedge of concrete supporting your end arch bricks (pic 4) without additional concrete. I feel that both the steep angle in the front and relatively flat arches would exert too much pressure (in combination with heat cycles) for their existing supporting structures.
Nice decorative brickwork!

[DrakeRemoray]

Re: Insulation question

I say add an inch of cladding. I have extra cladding on my pompeii (about an inch) and it is not too much for pizza and tapas and it is nice to have the extra retained heat for baking.

[melvynhoare]

Re: Insulation question

If I add an inch of cladding should I also use re-inforcing mesh?, would it then be better to add 3/4 inches of blanket followed by loose vermiculite or vermicuile concrete.

Thanks for all the posts and replies I am ready tp proceed but unsure which is the best option.

[Mojoe]

Re: Insulation question

1" will not require reinforcement unless you are concerned about cracks, more for aesthetics in which case you would use a fiber reinforced concrete. Any cracks you may get will be covered up by your insulation. General rule of thumb is the more insulation the better. On my barrel I have 3" of Inswool HP (2600F) blanket and 2" of loose vermiculite under a wood enclosure..temperature inside never exceeds ambient.

[melvynhoare]

Re: Insulation question

Thanks everybody for your imput I have gone for I inch + of cladding with a reinforcment sheet, just in case, I will add three inches of banklet then fill the void with vermiculite. Hopefully this will allow my oven to function as I want it to.

[Mojoe]

Re: Insulation question

Best of luck.