Justin Pompeii

[Justin]

I have a few questions, hopefully someone here can help me with.

Firstly i am planning on using a 50mm (2") slab of insulating concrete with 2 layers of 12mm (1/2") insulating board. Ive been told the insulating board is far superior to insulation concrete and i can probably just use it by itself, however i thought i would compromise and just add a thin 50mm (2") layer of insulating concrete, what do you guys think about this?

Next, i was originally planning to use 50mm (2") refractory bricks for the oven floor, but then changed my mind to use the 75mm (3") thickness bricks, has anyone got experience with this? is 75mm too thick?

Lastly, has anyone added a thermal break between the vent arch and the oven dome? im wondering this because we seem to go to so much trouble to insulate the dome and yet the heat can travel from the dome out through the front archway of the oven.

Sorry for 3 questions, and thanks to anyone who can help me!

[exipnos]

As far as floor thickness goes, I also went with 70mm brick. Having asked the same question myself the answer is that its not to much thermal mass since after all its less then what your oven walls of approx 4".

For floor insulation I installed 10cm AAC block. Its a light weight cellular concrete that have similar properties to the vermiculite insulation concrete. If your supporting slab is already completely level and smooth the installation is very simple since its flat squares approximately 62 by 50 cm big. There are some threads here on FB that discuss this material and there are a few builders that have used it with good result. Check it out. If you where to combine your two materials (insulation board and insulation concrete) I would think it will be easier and better to combine insulation board with the AAC instead.

Just my take on this but by no means am I an expert so take it with a grain of salt

[Justin]

Thanks Exipnos, you have given me the reassurance that i need for the size of the firebrick floor, i just have minor freak outs some times and feel im designing this thing the wrong way. As for the insulation board, i have already acquired it, its called ISOMAG 70 Structural Insulation. And instead of using vermiculite i have something called Shiralite 120LW.
I guess if the normal thickness of insulation is about 100mm (as is yours), and im using 50mm + (2 x 12.5mm) = 75mm, it should be fine. Thats my theory anyway

[exipnos]

Hi Justin,

Just a recommendation. I'm not sure if you have decided on your dome assembly method but if you have not then I definitely recommend that you go ahead and taper your bricks. I have not and I regret it.

Cheers,
Kosta

[amber]

justin,

I've heard about people leaving a break between teh arch and dome, but for expansion/contraction reasons. I have no idea if this is a good move or not. Maybe someone who has done it/thought about it can weigh in?

[Frances]

Originally Posted by Justin

i just have minor freak outs some times and feel im designing this thing the wrong way.

Don't worry, that's all part of the construction process. You'd probably be doing something wrong if you didn't feel like that...

When I was building my dome there were a lot of discussions about having a thermal break between the dome and the archway. I can't remember if anyone actually went that way in the end - the consensus seemed to be that it would be more trouble than it was worth. The heat has to go out somewhere eventually. I believe its also a structural thing, if you have an added break just there, the archway may not tie in with the dome so well.

Somebody even had these really neat plans for an inivisible thermal break inside the dome floor just under the doorway. Does anyone remember who that was?

[Justin]

Originally Posted by exipnos

Hi Justin,

Just a recommendation. I'm not sure if you have decided on your dome assembly method but if you have not then I definitely recommend that you go ahead and taper your bricks. I have not and I regret it.

Cheers,
Kosta

I was originally planning on not tapering my bricks but i am now thinking otherwise. ill probably end up cutting them as im a bit of a perfectionist.

Originally Posted by amber

justin,

I've heard about people leaving a break between teh arch and dome, but for expansion/contraction reasons. I have no idea if this is a good move or not. Maybe someone who has done it/thought about it can weigh in?

I hope so I guess its not that bg of a deal then since noone seems to do this and thier ovens all work fine..

Originally Posted by Frances

Don't worry, that's all part of the construction process. You'd probably be doing something wrong if you didn't feel like that...

When I was building my dome there were a lot of discussions about having a thermal break between the dome and the archway. I can't remember if anyone actually went that way in the end - the consensus seemed to be that it would be more trouble than it was worth. The heat has to go out somewhere eventually. I believe its also a structural thing, if you have an added break just there, the archway may not tie in with the dome so well.

Somebody even had these really neat plans for an inivisible thermal break inside the dome floor just under the doorway. Does anyone remember who that was?

Yeah probably just better to keep it simple. thanks for the advice everyone!

[Justin]

Ok, so i made a very elaborate formwork for the insulating slab layer, only problem was that i made the mix too watery and now it taking forever to dry (yes i am impatient) so now im doing other stuff like making forms for door arches etc while i wait.
I cant wait to get the floor on!

[Bandrasco]

Looks great Justin!

[nodoubt68]

Hi Justin, love ya work so far. I also like your design with your dual firewood boxes. Good luck matey, looking forward to watching your progress.