Brooky Tom's 900mm build Brisbane

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

In thinking ahead to the heat curing, I see recommendations to start with low heat and preferably fan heaters etc. Can I ask if the heat curing is usually done with or without the insulating blanket?
Also, I still have to construct the landing arch and flue etc but do people cure the oven; and add the insulating layers to the oven etc prior to the outer arch work? Getting my heat break ready might slow me down for the outer arch but I thought I could start on the heating and insulation of the oven build now if that was to work?

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

At this stage we removed the IT and decided to fill the oven with sand as the support for the upper layers. It was reasonably convenient as the back half is at ground level and it was easy to shovel the sand from a barrow into the oven. Photos show the oven with a central gauge inserted and then with the mound of sand. I found I had to top up the sand after each course as the brick layer just completed would have its upper (inward) edge above the sand level slightly. We have a height restriction (shed guttering) for the oven so we were keen to keep to the originally planned height and it worked out OK.
Last photo is the 6th course completed.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

next photos show part way through the 5th course; and then when finished this course and the inner arch.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Next photos - following other advices I inserted some screws into the bottom layer mortar to help tie down the insulating blanket later. Can also see the calcite sheets below the hearth - 2 layers of 25mm each. Vermiculite/perlite layer below these.
Around the 3rd and 4th course, I tried to tie the arch bricks into the oven course bricks as much as possible. Photos show some of those interaction bricks.

[david s]

Re: Brooky Tom's 900mm build Brisbane

In searing summer heat the bitumen on roads tends to melt, way to hot to stand on in bare feet. But as yours is under your 4" of vermicrete slab it will be well away and insulated from the heat. I'm sure you won't have any dramas.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

This shows the hearth area complete with the ply floor and IT, and then a couple of photos around the third course

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Sounds grim to pull it down. I'll proceed and hope for the best.
Photos attached show my trial arch, the vermiculite/perlite layer and then the hearth bricks. Claypave sold 450mmX300mmX25mm hearth bricks so I thought I'd try them, being larger than the 300X300. The photo shows the basic layout of those but I then filled in the other areas for the oven plan area

[brickie in oz]

Re: Brooky Tom's 900mm build Brisbane

I had this awful feeling that the heat might cause a bitumen taint to the pizzas!

And whats wrong with tar pizzas? you could start a trend.......

Pull it down and do it properly.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

OK so for the last two weeks I have been "having a crack" at the build with much trepidation. Help from friends and brothers-in-law have been gratefully received and I've tried to remeber all the very useful advices and tips on te many threads I've read (unfortunately I tend to forget who said what where so it takes some time to peruse the threads again - should have taken notes of course!).
I have taken photos on the way but haven't always been able to go on-line or access photos so this is a bit of a catch up. It's the rough version build so no model but I'm keen to see it finished and operating (as are the many people who will use it as it is a shared recreational area we plan to use a lot).
These first photos show my initial work at trying to establish a rising damp barrier. I'd said earlier that my base is half at bench height where I've built a beam/slab and half outside where it sits on ground. Unfortunately I didn't damp prrof the slab on ground so it was suggested to use builders plastic and bituminous paint on the slab, which I then covered with vermivulite/perlite mix and the insulation layers etc. After I laid it I had this awful feeling that the heat might cause a bitumen taint to the pizzas! Here's hoping my fears are unfounded.
Photos show the layers and the base shape.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Well I have been out of action for a while but started on the oven last week. Learnt a lot since then and have shaved fingers to show for it. Band aids a plenty. I'll post photos of the progressive build when I can. I have just finished course 5 which also coincided with closing the inner arch. Never laid a brick before so the inside is quite rough but I take heart from the comments that suggest most get hidden and it's the food that counts. I've gone with sand as the support for my upper courses and will be interested now to see how that works out.

[david s]

Re: Brooky Tom's 900mm build Brisbane

Regarding the heartbreak I think it is a good idea to use a u shape rather than a full rectangle or square. The ushape will conduct less heat from one side to the other and particularly if quite thin, say 0.55 mm, will flex a little. A heat break if made of a flexible material can also act as an expansion joint. In my design I placed my heat break between the entry and the outer decorative arch, because I was unable to place it between the entry and the dome and my entry , being cast is really light anyway. Stainless is a superior material to use over Aluminium because it is harder (more durable) and has a much lower thermal conductivity than than Aluminium (about 20x less) and you are after all trying to reduce the transfer of heat.

[Greenman]

Re: Brooky Tom's 900mm build Brisbane

Tom - I used 25mm S/S RHS on the floor and sides for my heat break. The top and under the floor strip and behind the sides is vermicrete and the sides have been covered with ceramic fibre/vermicrete and render. The S/S is very light gauge and the whole thing seems to work well. There is 100+ degrees the difference between the oven floor and the entry floor. The temps were taken either side of the stainless.

Pic of break attached. (The first one was MK 1 outer arch, MK 2 is buttressed.)

[Bacterium]

Re: Brooky Tom's 900mm build Brisbane

Tom,
depending on how you do the heat break around the arches.
if the blanket is over the top, to stop any blanket being exposed underneath I did a layer or vermicrete(technically I used perlite).

Heat break down at floor level, haven't tackled it on mine yet.

[cobblerdave]

Re: Brooky Tom's 900mm build Brisbane

Gudday Tom & Steve
Early in the forum the plain render dome, minimal depth full arch entry with straight steel chimney was known as the Australian igloo.
Check out David s advatar for what is probably the best example I can think of . The cast entry enables it to have bare minimum of entry depth and maximum use of what is a small entry ...his is a 21 in oven? ( sorry if I have got that wrong David)
Anyway just good for thought,
Regards dave

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Thanks again to all. I want to assure all that I read and take notice of all comments and appreciate the expert advice. I don't reply to each necessarily just to keep the thread smaller - but I do take in comments such as Dave, Steve and Chip recently and others before.
The forum is such a good source and of course with such a wealth of material many of us will not keep abreast of all the info. Gems are buried in long threads and I'm flat out remembering who had the good advices on various subjects. Between all of the contributors I just wanted to let people know I am very grateful.
Amongst all of that I had not read Wayne till today ( corner build grafton) and again good Info from Wayne and the responders. So I know I'm missing as much as I have observed.
My next query relates to the heat break. This seems to be a more recent discussion point but seems to be implemented frequently now. I don't think the FB manual discusses. From what I've seen, it is recommended to reduce the heat loss from the oven to the landing and thence to the surrounds. I've see a few mentions of a ss box channel of small dimensions in the space between the oven and landing hearth bricks; and reference to air gaps in the upper arch areas. For example, Wayne has now shown such a gap.
Any good advices appreciated. From what I've read, I'd run a small box section across the entry to the oven, but not sure what to do with the arch gap. Is it to leave a few mm between to stop conductivity between bricks and then cover the gap with the overall insulating blanket. That seems ok if it works and I have that correct. My hearth brick slabs are 50mm deep so I assume I will seek a channel 50mm deep and say 25 to 40mm wide. Can it be a channel rather than a box? (Ie three sides are sides and top) and can it be aluminum rather than ss.
And recommendations re the air gap in the arch? 5mm?
Thanks again all