Chch NZ build

[John French]

Re: Chch NZ build

By using a hinge from the centre with the I tool attached it meant that instead of describing a circulat arc it will produce an ellipse and therefore generate a lower height. My original though was to produce a lower dome than puely hemispherical one. However, I only used the i tool as a guide rather than as a brick placement device and not at all for the upper chains.
There are some good examples on the forum with more detailed information.

[John French]

Re: Chch NZ build

Spent the weekend mainly planning and revisiting design ideas re the outer arch and vent. It was really difficult to resolve some concepts. In the end i decided to follow a previous build with a flared opening and although this meant a few tricky cuts on a tile saw the outcome was okay. I am worried about the stability of the vent walls as the arch is built but hopefully it will be able to withstand the lateral forces even though there does not seen to be too much holding the structure up. I am down to my last 6 bricks and so i am trying to estimate how many extras i will need for the vent and support for the flue. Not sure what the chimney will be contsrtucted of yet.

[brickie in oz]

Re: Chch NZ build

You will need to provide some sort or lateral support otherwise it will all just collapse over time.

[Faith In Virginia]

Re: Chch NZ build

You will need to provide some sort or lateral support otherwise it will all just collapse over time.

Agreed!!! Mine held up fine till I put some heat to it then I started to get cracks and loose arch bricks.

This is my before and after. In the first picture you can see the cracks in the key joints and at the bottom of the arch where I got spread you can see where the arch pushed out

[John French]

Re: Chch NZ build

Hmm! That was a worry for me. I did a seach on vent wall collapses and found no real help there. I concluded ( falsly it would seem ) that there wasn't a general problem. I will trevist some other builds and look to find a way of improving lateral support.
Note your extra support, FIV , with extra bricks in front of arch and floor.

Any other thoughts out there?

[Les]

Re: Chch NZ build

John,

I dropped some rebar into the hearth and then used cored bricks to "beef" everything up. I'm having no issues. I really don't know if it was needed but it seemed like the safe thing to do.

Les...

[John French]

Re: Chch NZ build

John,

I dropped some rebar into the hearth and then used cored bricks to "beef" everything up. I'm having no issues. I really don't know if it was needed but it seemed like the safe thing to do.

Les...

thanks for the info.
I thinkyour solution may be difficult for me unless i dismantle a significant number of bricks. I guess an option is to double up the vent walls or change my planned igloo for an enclosure with lateral support form the structure.
I am not intending to put any other load on the outer arch as i intend to support the vent on the side walls and inner arch / dome.
I am suprised there are not more threads reporting problems re outer arch.
Hopefully a few more builders are willing to share their knowledge and experience.

[John French]

Re: Chch NZ build

John,

I dropped some rebar into the hearth and then used cored bricks to "beef" everything up. I'm having no issues. I really don't know if it was needed but it seemed like the safe thing to do.

Les...

Just checked out your pictures - very useful. I think that will allow me to proceed and if i need to add the extra decorative arch / brick work. I do have room for it although it will take away the oven landing that i had earmarked for a counter.
At what stage did you decide to add the extra brickwork - or was it your intention from the off?

[Les]

Re: Chch NZ build

John,

I think the decision to add it came after I realized how much weight I was going to put on top of the entry way.

Les...

[John French]

Re: Chch NZ build

I went ahead and built the outer arch. I may well end up having to build and extra decorative arch and reinforce the vent walls to add more stability. If i do this i will use bricks the same as our house to coordinate. The outer arch turned out okay although i am even more concerned as to its ability to stand up to the stress and strains of repeated heat cycles. I removed the form after about an hour and cleaned up the grout lines.
hopefully we have had our aftershock for the day having had a big one this morning!! About 3.2 on the Richter scale.

[brickie in oz]

Re: Chch NZ build

and reinforce the vent walls to add more stability.

You sure will, gravity will win and push the arch towards the ground.
The arch will want to flatten out with gravity, its a fact.

[John French]

Re: Chch NZ build

After a pause for thought I have resolved to fit a stainless steel flue. The availability of clay liners was nil, and to order a 10 inch one was not available for immediate delivery. Having seen some builds with the SS flue left exposed I am considdering that option. Although to build a brick chimney which will also reinforce the outer arch may become a necessity. The key for me was the ability to proceed with the vent installation asap - I was also able to get a good deal by buying direct from a flue fabricating factory.

[John French]

Re: Chch NZ build

Finished the brick vent today. After spending a long time thinking about the construction it is slightly disappointing to report that i would do it differently given the chance. However, although not perfect i think it will be adequate. I need to cut and fit brick to act as a shoe for the SS flue.
Does anyone know whether it is best to mortar the flue in or leave it 'loose' so it can expand freely?
If the latter how is it best to seal it?

Photos now added - be kind!

[brickie in oz]

Re: Chch NZ build

Wheres the pics?

[Drewaudio]

Re: Chch NZ build

Hi John,

I've started an oven build in Hamilton, New Zealand but you're much more advanced than I am. It's good to find another kiwi working on a similar project so I can ask some questions! Did you use regular cement mortar for the arch or did you use refractory mortar?

Cheers!
Andrew