New 36inch castable build in Brisbane

[brissie]

I have been scouring the forum for how to information on building an oven over the last few weeks. Now I have worked out how I am going to to it.

This last weekend I started construction. The dream to make a wood fired oven has been simmering for a few years, now its time to make the dream a reality.

The space I have is not large. I and need access to get past the the rear of the oven to get to the garden shed etc. Access to the oven will be from a large paved entertainment area.

[david s]

Re: New 36inch castable build in Brisbane

Post some pics. Are you aware that you could be in trouble if you build closer than 1.5 m from a boundary fence should you have neighbour issues?

[oasiscdm]

Re: New 36inch castable build in Brisbane

Hi Brissie

Welcome aboard. you are in the right place. enjoy the build.

[UtahBeehiver]

Re: New 36inch castable build in Brisbane

Welcome,

There are a couple castables, Mikku and IronPony that may be of interest to you.

[brissie]

Re: New 36inch castable build in Brisbane

David s

No problems, I have quite some distance from neighbours boundaries, but rather it's the setting that constricts space... I like the bush look and need access to the garden shed.

Oasiscdm

Yes this forum is a great knowledge resource, many original ideas. I will be asking for input on the best ways to do my build.

UtahBeehiver

Thanks, I will check out the builds.

First off I have decided on castable over bricks because of time and the requirement, you do need a brick saw access for a long time to do it properly. My hat go's off to people who can do this. I think brick ovens are the best but a lot of work.

I have worked in the building industry but not for close to 20 years. The skills do stick though and I have good knowledge on (some) materials and how they work.

The photos show current progress. A mud map, shows the base design. Just an outline, I am tweaking the design as I go.

The top will be 1800x1200x75 (~6x4x 3") it will consist of 2 hebel PowerFloor (aerated concrete) boards 600 (2 foot) wide. And third board cut to fit between the blocks supported by steel, and internal H shape block walls.

Under the oven I will have 50mm brick slabs, 50mm cs board, and 150mm aerated concrete.

I did not use dry stacked blocks, I don't mind laying a few blocks as it gives you a lot of control and easy to level up.

[brissie]

Re: New 36inch castable build in Brisbane

Have completed the base blocks and bond beam. The beam across the opening has 12mm and 16mm deformed bar for strength. You can't easily bend 16mm, so the 12mm is used to wrap around the structure, and tie it down to the base. Only the corner vertical cores are filled with concrete and steel.

[brissie]

Re: New 36inch castable build in Brisbane

Next weekend is a long weekend, I have 3 days to play with. So I might cast the dome. I am thinking of casting the dome into 3 or 4 sections, and also separating the flue structure from the main dome to reduce heat loss through the opening.

I have most of the materials required. The castable is made in Thailand, 12*20 kg bags. I think I will keep 3 bags for the opening, and patching over the dome section joins. I also have Corfix 900 degree mastic to seal the sections to each other, and perhaps to the floor.

I have question. Is it best to seal the dome to the floor? The floor will be 300x300x50 (1foot x 1foot x2 inches) brick slabs. Or is it best to cut the bricks to fit inside the dome.

More photos of the base...

[david s]

Re: New 36inch castable build in Brisbane

It makes little difference whether the dome sits on the floor or around the floor. The advantage of having the floor inside the dome is that replacement of floor bricks is easier. There is more brick cutting required if the floor is inside the dome. Make sure you insulate under both the floor and dome sections.
The easiest way to cast a one off is to cast the thing in place over a sand dome mould which is then removed after the castable has set. Using wet newspaper between the sand and the castable leaves you with a pretty clean surface. Be careful when mixing a batch of castable as it goes off pretty fast. It is quite temperature dependent so start mixing small amounts at a time until you get the hang of it. Do not leave the bags in the sun to pick up heat prior to mixing. If it's quite a hot day then use chilled water. Cover the casting as soon as it's completed. The reaction is over in 24 hrs so you can remove the sand mould the next day.

[brissie]

Re: New 36inch castable build in Brisbane

David s

Does anyone ever replace bricks on the base? What is life of a brick in an oven?

If a bricks lifetime is long, It may not be worth the effort to make the base future removable.

Steve.

[brissie]

Re: New 36inch castable build in Brisbane

Just a photo showing the first half of hebel PowerFloor board. The second half will be placed and then covered with two full boards. The full boards will be stuck to the lower broads by liquid nails, and mortar around the edges to the blocks.

[cobblerdave]

Re: New 36inch castable build in Brisbane

David s

Does anyone ever replace bricks on the base? What is life of a brick in an oven?

If a bricks lifetime is long, It may not be worth the effort to make the base future removable.

Steve.

Gudday Steve
Yes there was an oven this year a secound hand oven with broken worn hearth tiles which were replaced. I can't find it at the moment but I remember it had a gas fitting as well that had to be cut around. They were tiles too not brick. I suspect tiles might be a bit more fragile than brick and I also suspect a lot easier to replace than brick.
Regards dave

[Gulf]

Re: New 36inch castable build in Brisbane

Just a photo showing the first half of hebel PowerFloor board. The second half will be placed and then covered with two full boards. The full boards will be stuck to the lower broads by liquid nails, and mortar around the edges to the blocks.

Will there be no structural concrete hearth layer to support the oven, or is this "Hebel Powerfloor" something I am not understanding?

[brissie]

Re: New 36inch castable build in Brisbane

Gulf,

PowerFloor, Is steel re-enforced aerated concrete. I has 6mm bars through it. Its an alternative to traditional concrete flooring. A single 75mm (3 inches) thick panel has an R value of about 1 (thermal resistance). The floor will be 150 (6 inches) thick. I will also have a 50mm (2 inch) calcium silicate board under the brick slabs under the oven.

The 1800 (6 foot) long boards will span from the back to the front, and allow for some overhang at the landing.

I am using this product, because it is easy to install (no form-work) cost about $70 per 1800*600 (6x2) sheet. Plus it adds an additional layer of insulation.

Steve.

[david s]

Re: New 36inch castable build in Brisbane

David s

Does anyone ever replace bricks on the base? What is life of a brick in an oven?

If a bricks lifetime is long, It may not be worth the effort to make the base future removable.

Steve.

Some people freak out if a crack appears and they feel the need to replace it. A cracked floor brick does not effect the performance though and is easy enough to live with.

[brissie]

Re: New 36inch castable build in Brisbane

cobblerdave

I am using 300x300x50 fire brick slabs. Not tiles. I am still not sure on what I will do. I plan on casting the dome next weekend, I do need to decide before I start.


Thanks for the info, I will be doing a search to see if can find any brick fails...