Starting over

[cobblerdave]

Re: Starting over

G'day
The ( hearth) floor the hardest to heat up. Funny about that as the the Fire is built on it. But as always heat goes up. Commercial available ovens have the Hearth foor as low as 25 mm to 50 mm. Why not use the standard size at the 75mm.
With the brick on your dome at 115 mm it's a balance.
Encapulate your oven mass with insulation and it will give you an oven that will give you an oven that will supply you over the weekend.

Regards dave

[thesharkbar]

Re: Starting over

Thanks David I understand what your saying my worry is more mass on the dome then the floor if I double up the floor ones I should be around the same without buying new ones for the floor

[david s]

Re: Starting over

I have a question, The floor fire bricks/pavers i will be using are 40mm thick, is this enough or should i use two stacked?

Depends how you want to use your oven. It's just like boat design, everything is a compromise. 2" thick floors are pretty popular. Thicker gives you more thermal mass meaning more stored heat, but longer heat up and more fuel used. Thinner means less thermal mass/ less stored heat, but quicker heat up. At 40 mm you should still have plenty of stored heat to do the family roast, but less heat available if you want to use the oven the next day without refiring.

[thesharkbar]

Re: Starting over

No work on the oven today, late night last night at work so I slept most of the day
But i did get out and purchased two sheets of ceramic fibre board at 30mm each which will give me a total of 60mm insulation under the floor and while i was there also picked up the fire blanket now i feel abit better and feel like im moving forward again
I have a question, The floor fire bricks/pavers i will be using are 40mm thick, is this enough or should i use two stacked?

[deejayoh]

Re: Starting over

Sorry - stepped away for a couple days - but I am glad I asked the question about the insulation. Looking at your pictures I just had a sneaking suspicion something was missing!

I am sure it feels like a bit set back but you will not regret it ever one bit. The oven will work right with insulation, hardly at all without it. Plenty of builders come here asking "why won't my oven get hot" and turns out they built the whole thing without insulation. So better now than later when you'd gotten through 4 or 5 courses of dome building.

[thesharkbar]

Re: Starting over

Couldnt help myself pulled it all down today and cleaned each brick numbered them then started to attempt to get the concrete and the granite out but i loosened the two top layers of the base brick work
I feel like im going backwards in the build but i know it will be worth it in the end
I will try and do the two rows of bricks before i go on my trip so it can set while im away
What is the ratio of perlite to cement?

[Greenman]

Re: Starting over

A brief investment on a good second hand 14" wet saw that you resell after your build is done is probably the thriftiest way of getting the job done right. You should get pretty much what you paid for it if you can buy it right.

That's what I did but unfortunately the tool hoarder in me possessed me and I still have it. I have used it to build 2 more since so I justify my indulgence that way.

[dakzaag]

Re: Starting over

Shark obviously has his priorities mixed up cause he is spending money and time on a cruise instead of his oven.

Hopefully he will come to his senses and we can help him get back on track.

[Gulf]

Re: Starting over

............I now have decisions to make start again or carry on ...............Decisions decisions decisions
I leave this saturday for a 7 night cruise so i guess i have just over a week to think about it

My advice is to "put it out of your mind", and enjoy your cruise. Come back rested,............. and then think about it .

[Volongo]

Re: Starting over

I really cant hire a saw for the price they want and the time I need it for, I working on a budget lol.

If you do decide to taper your bricks after you start again . I would suggest you buy a cheap dry saw, since you?re on a tight budget like pretty much all of us here. You can buy a new dry saw and multiple 14 inch diamond blades all for around $170. Add a good quality respirator mask like the one below and a $20 ear muff @ bunnings, suddenly you look like a PRO.

Sundstrom SR 100 Silicon Respirator Mask Size M L NEW IN BOX Never Used | eBay

[Novaslo]

Re: Starting over

See how others chime in. I would definitely say and agree. It is up to you and depends what you want to do with the oven.

If you knock down the first layers of brick and throw down some Casi Board then you can start over building on the insulated board. I bought mine from Forno Bravo in Salinas Ca. It is 2 inches thick. That is all you need and you build your dome on top of it. The floor of your oven can be firebrick laid flat in a Herring Bone pattern.

On the other hand - Could you cook pizza - yes you might be able to. But you wouldn't likely be able to do 10 or 20 as your floor would likely cool faster after you move the fire.
There is a hotel that I frequent and they have a wood fired oven. They cook pizza's for a lot of people, on every one they have to finish the crust in the oven - inside.

This is because their floor cools too fast.
Tear down a little bit and move forward.
That is what I would do, most likely.

[thesharkbar]

Re: Starting over

Thanks guys, thats why this site is so good there is a wealth of knowledge and guys and gals willing to share this thanks again
I now have decisions to make start again or carry on
My mistake was changeing plans and assuming that they were the same and the guy that sold me the bricks told me the decomposed granite would be ok and to just do a cement slab to have a level floor once again I asumed him selling bricks would know what hes on about as they have a wfo out front of the office
I know the minister of finance is not going to be happy as this will be my third start at the dome if i chose to go that way
One question i have is would i be able to cook just pizza if i continue or is my only option to start again or give up knock the dome down and the dog has a new fancy kennel lol
Decisions decisions decisions
I leave this saturday for a 7 night cruise so i guess i have just over a week to think about it

[Novaslo]

Re: Starting over

Think of it this way. The whole dome and the floor should not touch any concrete in the base. It should be completely insulated from it. As if the dome and floor are sitting in their own insulated world.

You have worked hard. And you seem to work really fast. Get it right and you will be happy you did.

Keep the dialog coming and we will chime in.
My oven cooks a pizza nearly perfectly. No struggle with getting the crust and the top to cook at a similar pace.

D

[Tscarborough]

Re: Starting over

Mass is not insulation. Insulation is always low density or reflective. Insulation works by reducing the ability of air to convect. High value insulation will thus incorporate an extremely light material with as fine a pore structure as possible.

Granite ain't it.

[dakzaag]

Re: Starting over

Cracks in your mortar joints are not nearly as big a problem as it is made out to be. In an oven that will experience intense heat cycles every time you use it, you are going to get stress cracks. The smaller the joint size, the less likely it will crack and when it does crack, the less likely it will be a problem.

Crushed granite is about the same as sand in terms of insulation. Personally I would stop now before you get a lot farther along and replace the granite with vermicrete. 6-8 inches is best, 4-6 will do. This is the same concern as your floor extending out to the edge of the slab, it will bleed heat away from the floor and make cooking a frustrating experience because you will always have heat escaping the oven via conduction.

The insulation layer under the floor is what allows you to cook into the next day and longer as it retains the energy in the oven. If you just intend to cook pizza with an active fire, then just go with the crushed granite and plan to keep an active flame going while cooking. It will still be slow to heat up and fast to cool down, and slow to cook, but you can use it that way.