Nick's Build in Sunbury

[Nick P]

Hi All,

I have been lurking for while and now its time to make a start. I already have an existing slab and will be starting the stand next weekend.

Now I have a few questions that I am hoping some people with some knowledge out there can help me with.

I am intending of doing a 5" vermiculite concrete(5:1) on the hearth. Is this enough insulation underneath?

Intending to do the cooking floor and dome out of refractory with home brew fireproof mortar. For the base of the dome is it best to sit the dome on the oven floor or next to it on the insulation?

For the outside of the dome I'm going to use 2" of superwool and then 2" of vermiculite concrete then 1" of cement render. Do I cure the oven before or after adding the insulation? With the superwool underneath with the vermiculite concrete get to any temperature that would cause it to crack due to steam? Also would you add a waterproofing agent to the outside render to water proof?

Sorry for all the questions, just prefer to ask and do it right the first time.

Will post photos soon.

Thanks,

Nick

[oasiscdm]

Re: Nick's Build in Sunbury

Hi Nick

Good to have another local person close by. I actually spend a lot of my time in Sunbury, partner, her kids, parents and brother all live there, and I have clients also in the locality.

Cant help you with vermiculate as I didn't use it. My preference for me was calsil board as its easy no mess and I'm told a better insulator even at 50mm.

From my research it is best to cure the oven either after fully insulating or when it is finished [I will be doing mine when finished]. I have spoken to the owner of a commercial refractory organization located in Sunshine. They cure all there commercial ovens after completion. I am also going down the root of Shiralite over the dome then ceramic blanket [actually ordered it on Friday] as per the same guys commercial methods. You also run the risk if the oven cracks getting ceramic fibre in the oven through those cracks. But you are using superwool so I am not sure here.

Water proofing agent is not necessary if you intend applying a finish coat over the render.

[mrchipster]

Re: Nick's Build in Sunbury

Hi All,

I have been lurking for while and now its time to make a start. I already have an existing slab and will be starting the stand next weekend.

Now I have a few questions that I am hoping some people with some knowledge out there can help me with.

I am intending of doing a 5" vermiculite concrete(5:1) on the hearth. Is this enough insulation underneath?

Intending to do the cooking floor and dome out of refractory with home brew fireproof mortar. For the base of the dome is it best to sit the dome on the oven floor or next to it on the insulation?

For the outside of the dome I'm going to use 2" of superwool and then 2" of vermiculite concrete then 1" of cement render. Do I cure the oven before or after adding the insulation? With the superwool underneath with the vermiculite concrete get to any temperature that would cause it to crack due to steam? Also would you add a waterproofing agent to the outside render to water proof?

Sorry for all the questions, just prefer to ask and do it right the first time.

Will post photos soon.

Thanks,

Nick

If yo can design a containment wall for the vermicrete a 7-1. Or up to 9-1 would be even better.

The wall could be as simple as a piece of sheet metal formed into a circle attach the ring together with rivets or sheet metal screws, make the circle about 2-3 inches larger in radius than the outer radius of your dome bricks.

The higher vermiculite mix will give you a much better insulation value.

The sheet metal does not need to be very thick 18 ga should be fine. The ring will be in tension and is very strong in that direction the vermicrete is very strong in compression and the ring will keep the edges from breaking down.

Use wood blocking to keep the ring in position while pouring and then the wood blocking can be removed later after the vermicrete has set. Leave the metal ring in permanently.

If you want vermicrete under your entry yo could use 5-1 there as you do not need as much insulation there. The containment wall fo the entry could just be screwed to the outside of the ring like a U with out facing tabs

Chip

[reccymech]

Re: Nick's Build in Sunbury

'We' seem to be getting a Victorian Chapter of the Order of WFO Builders

[nissanneill]

Re: Nick's Build in Sunbury

reccymech,
I'm keeping a list of all the Aussie members and keeping the Adelaide and SA members separate for obvious reasons,
We are certainly a strong group of members that continually are on the increase. Goes to show that we appreciate a great forum.
Attached is the list up to today of the members, however some, like in other countries have dropped off contributing.

Cheers.

Neill

[Nick P]

Re: Nick's Build in Sunbury

Hi All,

progressing slowly. I have built the base out of besser blocks and used 50mm SHS as supports across with cement sheet on top instead of a structural slab. I have some concerns about the ability of the slab I am building on to hold the weight but that is another story.

I poured the 5:1 insulative concrete base on the week end.

I am planing on building a 80cm oven. If I build a dome that is a half sphere that will give me an internal hight of 40cm. If I then follow the 63% rule for the inner arch that will give me 25cm for the inner arch, that just seems really low. Should I make the dome higher so the arch is higher? Any suggestions?

Please see blow pics of the progress.

[boerwarrior]

Re: Nick's Build in Sunbury

Nick

I just built a 32 inch Pompeii oven and the door height is 10 inches and I think it is going to be fine. We have an AGA stove in our kitchen and the height of each of the 4 doors is only 11 inches and we have never thought they were too small. We roasted a 25 pound turkey in the AGA last year and it fit thru the door

Neil

[cobblerdave]

Re: Nick's Build in Sunbury

Hi All,

I have been lurking for while and now its time to make a start. I already have an existing slab and will be starting the stand next weekend.

Now I have a few questions that I am hoping some people with some knowledge out there can help me with.

I am intending of doing a 5" vermiculite concrete(5:1) on the hearth. Is this enough insulation underneath?

Intending to do the cooking floor and dome out of refractory with home brew fireproof mortar. For the base of the dome is it best to sit the dome on the oven floor or next to it on the insulation?


For the outside of the dome I'm going to use 2" of superwool and then 2" of vermiculite concrete then 1" of cement render. Do I cure the oven before or after adding the insulation? With the superwool underneath with the vermiculite concrete get to any temperature that would cause it to crack due to steam? Also would you add a waterproofing agent to the outside render to water proof?

Sorry for all the questions, just prefer to ask and do it right the first time.

Will post photos soon.

Thanks,

Nick

Gudday Nick
Interesting you casting on oven with homebrew. There has been very few of this construction so its hard to figure how they work. One thing I did see was that you were going to use it as the hearth, the cooking surface. I would not do this as being sand based and soft you would suffer with sandy pizzas and food. Much better to use firebrick, pressed clay commons or pressed clay pavers.
Search "brick less dome on a shoe string" this a quite a comprehensive build. One thing to note is it was built on a metal framework which is not best practice due to the different expansion of metal and refractory. Better to use " melt fibre" super fine stainless steel product used in caste refractory.
I know of two caste ovens locally and both work well both have to be used carefully as the caste surface is soft and and the tools can damage the entrance and dome. Better to consider a brick entrance and ring of brick in the inside to protect the surface
Anyway I hope you find something of my thoughts usefull
Regards Dave

[Nick P]

Re: Nick's Build in Sunbury

Hi Dave,

I should clarify. I am intending to use 230x115x75 Fire bricks for the base and done and homebrew as the mortar.

The base I have laid in the photo is 5:1 insulative concrete and I will put down a slurry of fireclay and sand to bed the fire bricks on.

One question I have is when doing the entrance to the oven should you put in a thermal break? I assume that these fire bricks would just act as a heat sink and bleed the oven of heat? If you put in a thermal break in the arc you you also put it across the floor?

I was thinking about putting 1 inch of Vermiculite concrete between the inner arch and the entrance.

Going to go get the firebricks today and lay then this weekend.

Thanks,

Nick

[cobblerdave]

Re: Nick's Build in Sunbury

Gudday Nick
I have no thermal break. The entrance and brick chimney are heated up by radiant heat and hot gases at the same time as the oven. Heat migrates slowly through the brick surfaces ( and more slowly through the insulation) so there's no major hemorrhage of heat just through that small amount of brick. My oven keeps heat for days. Check out Karagi Dudes build in the Aust section he has a set of readings that will explain a lot
But it's a "good to have " to have you oven retain max heat and it also provides a stress break between the oven and the dome. So that call is yours , its not a major thing regardless which way you go
Regards dave

[Nick P]

Re: Nick's Build in Sunbury

Hi All,

Read Karagi Dudes build last night, that is one fantastic looking oven.

Is there any ideas on if it is best to lay the bricks for the dome? on the insulation next to brick floor or on top of the brick floor?

I have also read that is laying on the brick floor put some card board in between the first course and the floor so the mortar does not bond the dome to the floor so it will float. Does this hold try for laying next to the floor or is it not necessary as you are laying on the bed of sand/fireclay?

Hope that makes sense to some one.

Thanks,

Nick

[mrchipster]

Re: Nick's Build in Sunbury

Hi All,

Read Karagi Dudes build last night, that is one fantastic looking oven.

Is there any ideas on if it is best to lay the bricks for the dome? on the insulation next to brick floor or on top of the brick floor?

I have also read that is laying on the brick floor put some card board in between the first course and the floor so the mortar does not bond the dome to the floor so it will float. Does this hold try for laying next to the floor or is it not necessary as you are laying on the bed of sand/fireclay?

Hope that makes sense to some one.

Thanks,

Nick

There should be no direct bond between the oven floor and the dome. If putting floor inside the dome wrap the outside if the floor with corregated cardboard, it is also a good idea to tape the seam between the floor wrap and the floor cover so mortar does not fall into the space between the two pieces, and cover the floor so as not to drop mortar on the floor bricks while building. If putting dome on the floor cut a piece of cardboard larger than the floor and build your dome on the cardboard.

Clear??

[Nick P]

Re: Nick's Build in Sunbury

Thanks Chip.

I assume there is no right or wrong way of doing it? Dome on floor or next to?

Thanks,

Nick

[mrchipster]

Re: Nick's Build in Sunbury

Thanks Chip.

I assume there is no right or wrong way of doing it? Dome on floor or next to?

Thanks,

Nick

The theory is that if you need to replace any bricks in the floor it can be done for all bricks if inside the dome. If dome is on the floor some of the outer bricks could not be replaced.

The middle bricks ar more likely to have wear so it may be a non issue, my floor is inside my dome but I am not sure it makes a difference.

[oasiscdm]

Re: Nick's Build in Sunbury

Hi Nick

My floor is also inside the Dome with about 4 mm gap to dome.

My view [whether right or wrong] is that bricks will expand if dome bricks on the hearth it will all expand together hence having the dome float on the hearth. Having them separated they in theory move separately.

As I said not sure whether one is better than the other but just my logical brain thinking keeping the two separate.