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2 meter diameter New build oven with pumice reinforced with Basalt Rebar

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  • Alomran
    replied
    Originally posted by Gulf View Post
    Sorry for the late reply.
    In my opinion, soft insulated firebrick should be sealed from any compartment that food is cooked or passes thru during the cooking process.
    I have put 2 pieces of Kiln insulate refractory bricks on the arch which I can replace easily, Is the light weight Kiln insulate refractory bricks present a health hazardous with food?

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  • Gulf
    replied
    I should have elaborated a little more about that. You can see an example of it my pics above. Since I have a roof over the build, I have a good example of how not to do it. Where the dome meets the chimney can create a sharp valley where water can collect during a hard rain. This valley is a bad place for different types building materials to intersect, stucco/render to brick for example. That will result in a cold joint that is difficult to waterproof. Even with the same material, the sharp change in direction is subject to crack. That means water intrusion. If freezing weather is figured into the equation that means further damage. Building this area up level across from the apex of the dome or at least contouring this transition will save some problems in the future.

    Building without a cover leads to another area that needs to be addressed. It may well be the easiest point for water to enter the oven. That is the oven entry. Forno Bravo and some other companies address this with a brow over the entry. That will help with a normal rain. With a wind driven rain, that is not enough, imo. I included a storm door with my build for that. It takes another reveal on the face brick or in the stucco for it to work.

    Also, Make sure that the ledge or landing is lower and slopes slightly away from the entry for water drainage.

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  • Alomran
    replied
    Originally posted by Gulf View Post
    Alomran,
    Since you will not have a roof cover, make sure that you build up the area behind the chimney level with the apex of the dome before installing your final render/stucco and or tile.
    Thanks Gulf for the great idea about cantilevering concrete. I was going for an over kill by bolting L shape metal to hold the vermiculite+pumice mix.

    Sorry, but I didn't get what you meant in the above quote ;(
    Did you leave the metal roofing sheet sandwiched between the ceramic blanket and the vermiculite insulation? or did you pull it out?
    Is the light weight insulate Kiln bricks health hazardous with food?
    Last edited by Alomran; 10-02-2019, 03:24 PM.

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  • Gulf
    replied
    Alomran,

    It doesn't appear that you have enough room on the sides of your hearth for the insulation layer. I'm not sure about the back. I had the same problem. I took care of that by pouring a reinforced concrete cantilever ring to support it. After forming the ring, I placed a thin sheet of roofing metal against the ceramic fiber insulation. My thinking was that it would help keep from compressing the insulation and keep the insulation from wicking water from the concrete. Once that had set I installed the vermicrete. The last pic shows a mesh that I installed over the vermicrete with spacers. I then installed what I called at the time a stucco layer. It was not a coventional stucco application. More like water resistant ferrocrete. That layer is very strong and water resistant. It is not a breathable layer like true stucco. That is where a vent comes into play and is very necessary with a water proof outside shell. I did lot of cooking in the oven prior to installing the brick venier and had no cracks. To date there are no cracks in the outside shell.

    Since you will not have a roof cover, make sure that you build up the area behind the chimney level with the apex of the dome before installing your final render/stucco and or tile.

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  • Alomran
    replied
    Originally posted by Gulf View Post
    I may have a different understanding of exacly what type of "bubble aluminium thermal insolent" that you are referring to. Aluminum melts @ around 700 degrees F. Im not sure that 1" of ceramic fiber is enough insulation to prevent that from happening at the apex of your dome. The type of insulation that I am famiiar with ( aluminum foil on both sides) has PVC plastic foam with air filled cells that will melt at an even much lower temperature. . The aluminum foil will also help keep moisture in, if there is no other means for it to escape. Some of us have installed vents for this.

    Three inches of ceramic fiber blanket or the equivelant is the minimum recommended for the dome. I think that it takes twice the thicknesss of 10 to 1 vermicrete to be the equivelant. So, that would be at least another 4" of vermicrete. I hope that others will comment on the pumice. I have no idea what that adds or subtracts from insulating efficiency.

    You really need to think again about covering this beast with roof to keep the water out imo.
    Thank you again for the great info.
    In this case, I will add 6 inches of vermiculite mixed with pumice as a thermal insulation.


    Will tiling the dome using a Dunlop specified for swimming pools ( Water proof) tile adhesive for swimming pools be a good option to protect the exposed dome from water going through dome cladding?

    Perhaps, adding a layer of water proof black paint (made of asphelt) on top of the 6inch cm vermiculite is safe enough?

    Unfortunately, I live in a green belt with a local committee of retired people, I have aggravated them during the 4 year waiting for the oven to be completed, as the oven is visible from the outside ....my next door has contacted the local council and the local fire brigade as well as the planning department to stop the construction of the oven. Therefore, canopy is out of the question as I may be breaking the deed of the land/house purchase> I need the shelter for keeping the oven dry as well as protect it from a falling falling tree as the garden is part of a woodland.I have incorporated some steel into the concrete hearth with the intention to add acro supports at each corner to provide a metal frame to protect it from medium size branches falling on windy days..
    Attached Files

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  • Gulf
    replied
    I may have a different understanding of exacly what type of "bubble aluminium thermal insolent" that you are referring to. Aluminum melts @ around 700 degrees F. Im not sure that 1" of ceramic fiber is enough insulation to prevent that from happening at the apex of your dome. The type of insulation that I am famiiar with ( aluminum foil on both sides) has PVC plastic foam with air filled cells that will melt at an even much lower temperature. . The aluminum foil will also help keep moisture in, if there is no other means for it to escape. Some of us have installed vents for this.

    Three inches of ceramic fiber blanket or the equivelant is the minimum recommended for the dome. I think that it takes twice the thicknesss of 10 to 1 vermicrete to be the equivelant. So, that would be at least another 4" of vermicrete. I hope that others will comment on the pumice. I have no idea what that adds or subtracts from insulating efficiency.

    You really need to think again about covering this beast with roof to keep the water out imo.

    Leave a comment:


  • Alomran
    replied
    Originally posted by Gulf View Post
    Sorry for the late reply.
    I would skip the bubble wrap and add some more refractory insulation. Either, another layer of ceramic fiber or a few more inches of the vermicrete type insulation.
    Thank you for the great guidance, the reason I've considered using aluminium is due to the fact that for neighbourhood issues, I will not be able to build a canopy to protect the dome from the elements of the British weather, including the endless winter rain.So thought of the aluminium wrap as act as a water membrane against water going through the external cladding/tiles and through the vermiculite;ite insulation. Given the dome is over 7 meters in area, so for financial reasons only 1 inch ceramic blanket, what thickness of vermiculite/pumice should be added?

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  • Gulf
    replied
    Sorry for the late reply.

    In my opinion, soft insulated firebrick should be sealed from any compartment that food is cooked or passes thru during the cooking process.

    The brick in the back of the entry, directly above the inner arch get extremely hot.

    I would skip the bubble wrap and add some more refractory insulation. Either, another layer of ceramic fiber or a few more inches of the vermicrete type insulation.

    Leave a comment:


  • Alomran
    replied
    I would like to consult the wise team at this gI have just managed to nearly complete the dome, on the following matters:

    1- Is the chimney bay essential to be made of firebricks of the type that stores heat or is it possible to use the light weight vermiculite kiln bricks that is light in weight and thermally insolent, begging to point out the dome is made of 23cm thick firebricks dome thick? I am considering this option to reduce the weight on the suspended concrete platform carrying the arch bay.

    2- Is the gap between the dome and the chimney bay only as a thermal break to prevent a thermal bridge? or is it for reducing the thermal expansion that may occur in the dome as well as in the chimney bay that may cause crack between the 2 structures?

    3- Would using kiln bricks made of vermiculite be a good option to replace the insulation robe?

    4- Is 2 layer of bubble aluminium thermal insolent added on top of the 1 inch ceramic blanket and a 10cm mix of pumice and vermiculite be enough to insulate this massive beast?

    5- I have made a double arch to spread the immense weight of the weight of a 23cm thick dome wall on the entry arch, do you think this is an over kill? I just felt that in case there is a material failure, I don't wish to rebuild this oven!!

    I would appreciate your advice on these matters. Thanks
    Attached Files

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  • Alomran
    replied
    Hopefully I will cement in the arch and publish more images tomorrow.
    Attached Files
    Last edited by Alomran; 09-14-2019, 05:08 PM.

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  • Alomran
    replied
    Unfortunately, I am using only the grinder as I couldn't bother to rent out a proper cutting machine sue to esceeding my budget. Hence the brick cutting looks a bit wonky!
    Last edited by Alomran; 09-14-2019, 05:07 PM.

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  • Alomran
    replied
    After 4 years of neighbours complaining to the local council, sabbotaging my electrical cable to my allotment and following a threat from one of my sad alcoholic neighbours, to have a fist fight! I have decided to stop reinventing the wheel, I have decided to listen to the wise voices of many here including Karangi Dude and david s .
    I have decided to demolish the red brick soldier bricks and restart with the proper way by using firebricks.
    I have created a moulding frame made of timber for the dome, made of the weathered timber that has been sitting in my garden exposed to the element for 4 years.
    Please forgive the brick laying standard as I have never laid down a piece of brick.
    My work is very messy and does not live up to the standards of the rest on this forum.

    the internal diameter is now 192cm, The internal height of the dome is 75c

    m.

    The cost of a single fire brick in Surrey, UK is about 4 each + Shipping. I have purchased in access of 840 bricks.
    The project is well over budget and over sized and running 4 years late! Now I have restarted and racing against the English weather. I could not put a gazebo as the neighbours are getting mad with me with numerous retired busy bosses around.
    Last edited by Alomran; 09-14-2019, 05:27 PM.

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  • UtahBeehiver
    replied
    I really can't answer that because each build is different with different variables, some take longer than others. All I can say is the more you fire, the more you get to know the oven. I learn something new each time I fire mine up. I can give you one nugget of advice that came from David S, if you see a lot of steam you are going too hot too fast. He advocates placing a tarp over you oven and if there is condensate forming then the oven is still wet.
    Last edited by UtahBeehiver; 07-17-2017, 07:29 AM.

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  • Alomran
    replied
    Originally posted by UtahBeehiver View Post
    It all depends on how much water there is in your build, not only mortar but brick, insulation, etc. This where I see a lot of builders get impatient and crank up there ovens too high too fast only to ask why their oven cracked. You can still do some cooking during the curing stages. I recommend using briquettes during the initial stages of the cure, there heat is more easily controlled without flame spikes. You can BBQ yourself something at the same time. Slow is good.
    What is the ideal curing time in your opinion?

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  • UtahBeehiver
    replied
    It all depends on how much water there is in your build, not only mortar but brick, insulation, etc. This where I see a lot of builders get impatient and crank up there ovens too high too fast only to ask why their oven cracked. You can still do some cooking during the curing stages. I recommend using briquettes during the initial stages of the cure, there heat is more easily controlled without flame spikes. You can BBQ yourself something at the same time. Slow is good.

    Leave a comment:

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