another hearth question

[PizzaJNKY]

Re: another hearth question

I'm trying to upload some photos of my progress. I hope it works.

Oops, its not working. I have to figure out a way to shrink the photos.

[Frances]

Re: another hearth question

Hey PizzaJNKY, where are the pics? Think of us poor people who have finished our build and aren't likely to get the chance of building a second oven...

[PizzaJNKY]

Re: another hearth question

I reviewed asudavew's photo album, and noticed that his insulation layer looked just like my 6-1 ratio, so I stuck with it. I have a feeling I'll be copying his work for a long time. (I Hope you dont mind asudavew.) I just now finished my perlite/portland insulation layer, and now I get to hurry up and wait before I can continue with the rest of my build.

I just ordered the superisol board, refmix, and FB blanket, which should be here by next weekend. Looks like I will have a week to catch my breath.

So far, I have really enjoyed my build, and I have no experience with any of this type of work. Thanks to all my new FB forum friends for all you help and advise along the way.

[PizzaJNKY]

Re: another hearth question

Help needed with perlite/portland mix. For giggles, I mixed 6 shovels of perlite with 1 shovel of portland and water to see what it looks like, to make sure I get it right before the real pour.

I thought it would look like oatmeal, similar to the vermiculite/portland mix, but instead it ended up looking like wet course sand, similar to the kind I build sand castles with at the beach with my kids.

Is this what it is supposed to look like, or did I not make it right.

[gjbingham]

Re: another hearth question

Dang, darn! I'd love to see someone do it a bit differently!

[thebadger]

Re: another hearth question

My only concern that I read about is it would take a lot longer to heat up the floor... especially for pizza temps. I'm planning my floor now and am going with the flat side 2.5 inches.

Dick

[gjbingham]

Re: another hearth question

I like the idea. It would make all the bricks 4.5 inches thick throughout the dome.

[asudavew]

Re: another hearth question

I added a 3/4 inch coat of "poor mans" fire mortar over the top of my insulating layer. I wanted a nice smooth surface to lay my hearth bricks.
The oven seems to take longer to heat up than most others here, but it does hold heat well.

Pizza temps Saturday night, and brisket temps on Monday.

The hearth seems to hold temps well for pizza bottoms too.

Not sure if 4 1/2 inches would be good or not....

But try if ya wanna! It might be a positive change.

Then again... maybe someone has already done it.... If not ..

You are now the guinea pig!

I can't wait to see how it works!

[PizzaJNKY]

Re: another hearth question

Xjim, even though I'm not there yet, all this talk about heat retention, and whether or not it would be a good idea to add a 2nd layer of brick has got me thinking. I wonder if instead of laying the hearth layer fire bricks on their wide faces, it would be better to lay them on their 2-1/2" edges, making the floor approx 4-1/2" thick. Which would then change the height needed for the top of the dome, I think? I guess I won't really know till I get there, I'm more of a visual person.

[gjbingham]

Re: another hearth question

XJim,
Good question about the double layer of bricks on the oven floor. Perhaps even the half-thickness bricks? That would make the thickness of the floor almost as thick as the walls - somewhere around 4 inches thick. That would certainly help with heat retention. I wonder how much more fuel it would take to get the floor up to pizza temps?

What do you think? It would be relatively easy to place another temporary layer in there and test it out, huh?

[Dutchoven]

Re: another hearth question

JNKY
Anytime within 24 hours is fine...no need to push yourself and try to do both at the same time...even within the week is fine...don't finish the structural slab until it shines. just get it smooth and level...it will make boxing out the vermicrete much easier.
Best
Dutch

Thanks for the advice. If I can, I will do both tomorrow. Originally, I was not going to begin this project until May, when I start my 3 week vacation. I ended up starting sooner, working every weekend. I figured if I can finish the oven before I start my vacation, I can relax for 3 weeks and eat lots of pizza, instead of work my tail off. Good luck with your project badger.

[Xabia Jim]

Re: another hearth question

I'd recommend six inches of insulation for the floor vs. four. Or just 4 vermicrete and an inch or two of ceramic board over that. My biggest bitch about my oven is that the floor doesn't hold heat as well as the walls. (I used four inches of vemiculite/concrete).

I think you're right here GB

Since the hearth is your cooking surface, you want it hot and to stay hot. I added insulation under mine after it was done for the same reason. I may put a door on the wood storage area just to help hold just a bit more!

Now how much do you want thermal mass in the hearth and how much insulation? Would you consider two layers of firebrick overkill? Certainly not overkill to do two layers of FB board though, just more costly right?

[PizzaJNKY]

Re: another hearth question

Thanks Bingham. I do plan on adding at least 2" of FB board ontop of the 4" insulating layer. I guess I better order the FB board soon.

[gjbingham]

Re: another hearth question

I'd recommend six inches of insulation for the floor vs. four. Or just 4 vermicrete and an inch or two of ceramic board over that. My biggest bitch about my oven is that the floor doesn't hold heat as well as the walls. (I used four inches of vemiculite/concrete).

[RTflorida]

Re: another hearth question

badger is correct, the original idea was to have the 2 slabs bond together....pour the support slab, wait a couple of hrs, then the insulating slab. This is how I did mine; others since have poured on separate days with no ill effects, as badger mentions - there is a whole lot of weight that ends up on top, there isn't going to be any movement between the two (at least not any that has been varified).

RT