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?

[david s]

Re: Brooky Tom's 900mm build Brisbane

There are two schools of thought re curing before or after insulation and pros and cons for both ways.Curing without the insulation in place will drive the moisture off faster, but it will be more uneven. There will be a huge difference in temp between the inner and outer surfaces of the dome, which leads to uneven thermal expansion, stresses and possible cracking. Curing with the insulation in place will be slower, but will keep the temperature far more even. Unfortunately if you already have the blanket on you won't be able to easily inspect the exterior of the dome for cracking. If you have vermicrete insulation in addition then it's pretty important to dry this layer before making the outer shell (if building an igloo) otherwise you risk cracking the outer shell from steam expansion. I prefer to drive the moisture out with insulation in place.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Thanks David. I think I'll just use a heater at this stage while I do other things; and then put the insulation in place prior to any fire. I am planning the igloo shape and have bought the render but won't apply until after the curing. Can I assume OK to apply the vermicrete layer over the insulation blanket prior to firing?
With the render I have bought Dunlop acrylic render and Dunlop fine render. I gather from reading the instructions that the acrylic is for thicker applications and then the fine render is used for a final few mm thick application. Any contrary thoughts appreciated.
But I wait until moisture driven out before the render applications; and hopefully also after I have completed the landing arch/tunnel and flue arrangement.
Another question. I had intended that the landing arch be one brick length long (230mm) but I saw one thread which seemed to be a brick and a half? Any comments?
I plan to house a 150mm SS flue inside a firebrick mount just above the outer arch/tunnel. I was going to have the edge of the SS flue in line with the outer edge of the inner arch. But then I also intend a 25mm wide heat break (using SS channel) between arches so now I am unsure of that detail where the heat break intersects the chimney gap. I suspect I should place some form of firebrick separating the heat break from the space where the smoke rises up the chimney. Maybe a 25mm thick brick running across the outer arch gap? Or else, seeing the chimney area is an air gap in itself, stop the heat break SS where the outer arch bricks stop being full length. The latter is probably simpler and will mean I can keep the SS chimney flue right up against the inner arch edge.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Another quick question. I plan a reveal of 30mm. But I assumed that the floor was at a constant level, that is it was level right through from the landing to the oven. This means the door will not have a lip to sit up against on the base like it does elsewhere. Is this the norm? Or do some people build the landing lower than the oven floor? Thanks.

[UtahBeehiver]

Re: Brooky Tom's 900mm build Brisbane

Brooky Tom,

There is a new thread on doors by DJ. It shows quite a few different doors and I believe most all sit on a flat entry. Take a look.

http://www.fornobravo.com/forum/f9/s...tml#post157363

[brickie in oz]

Re: Brooky Tom's 900mm build Brisbane

Sounds grim to pull it down. I'll proceed and hope for the best.

Cool, dont forget that it will off gas for years, when your teeth and hair start to fall out youll know why.....

[david s]

Re: Brooky Tom's 900mm build Brisbane

You have what looks like 2" cal sil and 4" vermicrete between your floor and your bitumen layer. That is plenty to stop all heat from getting to it. Take a look at the link, which provides more links on bitumen info. Most of the planet is covered with bitumen roads.it's a natural substance that has been used for centuries.i'd like to know if there's any evidence that it causes hair and teeth to fall out.

Bitumen - A Smelly but Useful Material of Interest

[brickie in oz]

Re: Brooky Tom's 900mm build Brisbane

Make an informed decision, I wouldnt risk my families health.

Off-Gassing: Modified Bitumen Fumes | Foam Roofing

Asphalt

https://www.google.com.au/#sclient=p...w=1280&bih=855

[david s]

Re: Brooky Tom's 900mm build Brisbane

Thanks,
Good find.
It's a bit hard to avoid bitumen roads though. Maybe go bush where the roads are only gravel.

[brickie in oz]

Re: Brooky Tom's 900mm build Brisbane

Thanks,
Good find.
It's a bit hard to avoid bitumen roads though. Maybe go bush where the roads are only gravel.

David you have lost the plot my friend, we are here to help ppl not harm them with our advise.
Why risk your or anyone's health just to prove a point?
The bitumen that is painted on the concrete hearth is in an enclosed area (the oven), it will off gas there is no scientific dispute on this.
Depending on the product it may or may not cause cancer, and yet you say its ok to use?

The bitumen is buried under whatever thickness of insulation so what, the off gasses will still come out and find their way into the oven and the food, even more so when the oven is heated up, also dont forget the insulation will get warm to hot underneath.

Why risk it?
David, I bet you wouldnt risk it, yet here you are telling someone else to risk it and all will be fine.

[brickie in oz]

Re: Brooky Tom's 900mm build Brisbane

Brooky Tom, Im done with this thread, unsubscribing now.

[david s]

Re: Brooky Tom's 900mm build Brisbane

David you have lost the plot my friend, we are here to help ppl not harm them with our advise.
Why risk your or anyone's health just to prove a point?
The bitumen that is painted on the concrete hearth is in an enclosed area (the oven), it will off gas there is no scientific dispute on this.
Depending on the product it may or may not cause cancer, and yet you say its ok to use?

The bitumen is buried under whatever thickness of insulation so what, the off gasses will still come out and find their way into the oven and the food, even more so when the oven is heated up, also dont forget the insulation will get warm to hot underneath.

Why risk it?
David, I bet you wouldnt risk it, yet here you are telling someone else to risk it and all will be fine.

Al,
If you re-read my posts you will see that I was only referring to the heat affecting the bitumen. I acknowledged the evidence you supplied and thanked you for providing it. Maybe it's not too safe.

[cobblerdave]

Re: Brooky Tom's 900mm build Brisbane

Gudday
Refer to Brooky Toms post No 38 pic no 2
bitumus sealer then a layer of builders plastic
Tom no fumes are getting through that plastic, and then you have more layers of insulation than you could possibly imagine, heat is not an issue here.
Please note No internet reference were used in the production of this post
Regards Dave

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Thanks guys. I appreciate the advices and the concerns. As recently mentioned the seal is covered by a plastic layer which I thought would have prevented any off gases to enter the oven. Nevertheless I will be concerned and will try to set monitors for the temperature in that area. And any signs or concerns I will pull the pin.
Thanks again to all contributors.

[Brooky Tom]

Re: Brooky Tom's 900mm build Brisbane

Been a while but been busy setting up the area for my son's wedding. Did finish off the oven and will post photos once I get organised again. Hopefully soon.