First course

[Omaharosario]

Some new pics of our recent progress.

[Faith In Virginia]

Re: First course

I'm a bit confused by your pictures. Does your soldier course sit directly on your concrete slab then you filled the interior with something?

[Omaharosario]

Re: First course

I'm a bit confused by your pictures. Does your soldier course sit directly on your concrete slab then you filled the interior with something?

A little different huh?

The soldier course is sitting on the cement slab and filled with, First layer 1" 1800 degree fiber board, follow by 4" refractory cement, then a 1" 2300 degree board, then we will lay our firebrick cooking floor on top of that. The reason I am leaving the 2300 board and cooking floor out till we get out dome done is because we want all of the refractory to cure correctly. Not the most traditional way but we like it so far.

[Faith In Virginia]

Re: First course

I only ask because when you heat your oven the dome will get hot. But that soldier course to the concrete will wick your heat away from your oven to the concrete slab. See where I'm going with that?

[Omaharosario]

Re: First course

I only ask because when you heat your oven the dome will get hot. But that soldier course to the concrete will wick your heat away from your oven to the concrete slab. See where I'm going with that?

I guess I did not think about that, I thought the 2 boards and the refractory cement would be ok.. So when you put your soldier course on top of refractory, the refractory wicks the heat away from the cement? Any suggestions...

[Les]

Re: First course

Since its only the first coarse - I would pull it and insulate under it.

[Faith In Virginia]

Re: First course

I think the big trick is to heat just the oven bricks. (Your progress so far looks wonderful) so if you don't have an insulation layer between your solders and your concrete base as your trying to get your oven to temp your loosing some of your heat to the concrete slab. So it it were a swimming pool, you'd have a big leak if you know what I mean.

My thought is that I believe the oven will function as a pizza oven as it is but it won't be very efficient. If your looking to do more then pizzas and cooking days after the firing your oven will be at a disadvantage. So the choice is yours on (leave it as it is or get insulation under the solders) I know others will chime in on this one so I would give it some thought before you proceed any more.

[brickie in oz]

Re: First course

The heat will just trickle out trough the bricks into the concrete base and you will be forever feeding the thing firewood, been there done that with my first oven.

Everything needs to be off the concrete base and well insulated, even the entry bricks.

[Omaharosario]

Re: First course

What kind of insulation & the what amount you would apply under the soldier course to fix this problem?
Also I want to understand why this creates a huge leak and why the insulation changes that? Not trying to question you just want to be a informed builder.
Thank you for your input it it very useful.

[Omaharosario]

Re: First course

The heat will just trickle out trough the bricks into the concrete base and you will be forever feeding the thing firewood, been there done that with my first oven.

Everything needs to be off the concrete base and well insulated, even the entry bricks.

Thank you! How did you go about fixing yours??

[brickie in oz]

Re: First course

What kind of insulation & the what amount you would apply under the soldier course to fix this problem?
Also I want to understand why this creates a huge leak and why the insulation changes that? Not trying to question you just want to be a informed builder.
Thank you for your input it it very useful.

1" of calcium silicate board would help, 2" would be better.

Anything in contact with the oven itself will get hot and the heat will be transferred to what ever it touches. .
The more heat that leaks away the more wood you will need.
The entire oven should be cocooned in insulation, that way you will use less wood and have extended cooking time.
Done properly your oven should stay at cooking temps for days.

My last oven was near cold in the morning after a pizza party, my new one stays hot for a week and its all due to being properly insulated..

Thank you! How did you go about fixing yours??

I tore it down and rebuilt a new better insulated oven, it wasnt a chore for me because its what I do, bricklaying is a paid hobby for me.
But for someone who is only going to do 1 oven you may as well get it right to start with.

[Faith In Virginia]

Re: First course

I would use your 1'" fiber board under your solders. but your second issue is the 4" refractory cement that you plan to sandwich with your fiber board. If that 4" slab touches your soldiers then as you heat your oven you will also be heating that slab unnecessarily. so I would run the 1" insulation under and on the inside of those solders.

As far as why. the firebrick is dense and conducts (heat) energy very well. the concrete slab also conducts (heat) energy very well. if they touch each other the fire brick will transfer the (heat) energy to the concrete slab. The insulation layer will prevent that transfer of energy.

[Neil2]

Re: First course

It is not to late to tear it down and start over.

[GianniFocaccia]

Re: First course

It is not to late to tear it down and start over

I had all of my soldiers mortared in and tore them out because I felt they didn't bond well. I ended up starting with a horizontal first course and just went up from there. It didn't take me very long at all and I am tickled I took the time to do it right.

Regarding the refractory slab sandwich - why? If you want extra thermal mass under the floor (I have 3.75" total in my floor), place ALL of your insulation under the floor. It will be much more efficient, IMHO.

[Cheesesteak]

Re: First course

The best way to look at it is - your oven / dome should be "floating" on and surrounded in insulation. Anywhere the firebrick touches another hard surface (concrete slab, outside arch, countertops) - you will lose heat.

When you fire the oven - it's not just the floor and the top of the dome that gets hot. The bricks saturate with heat. When you saturate the bricks in the oven as you've built it so far - the heat will travel down the sides of the dome and begin to heat the concrete slab. The heat will continue to try to transfer to the concrete slab until it gets as hot as the firebrick.

Floating your dome on insulation prevents that heat transfer.