Fnbrokens Corner WFO in Canberra, Australia

[fnbroken]

A couple vent queries if I may...

1. Is there an optimal inner vent to outer vent radius ratio?

2. How much of a transition between the top of the outer vent and into the flue diameter is required? I recognise that the surface area of the vent needs to be greater than the flue - however does it need to be tapered at all? In the picture below, I essentially have it sitting flat on top of the serpentine arch... Note: the serpentine arch depth is the same as the flue diameter - 200mm.

3. If the flue base plate is bolted to the top of the arch - how important is it having more bricks on top of the base plate? Are they then just decorative? Or is more weight required to ensure it stays put?

[fnbroken]

oops...pictures attached...

[UtahBeehiver]

Greg,

Q1 - Not sure what you mean by inner and outer vent.
Q2 - Smoke takes the path of least resistance so the smoother the transition the better. But your design looks pretty smooth. Square area effectiveness of a square or rectangular vent is not as good as a round vent so the as your design shows the lower part of the vent area is bigger than your round adapter plate hole so good there.
Q3 - The top brick, IMHO, over the anchor plate are both decorative and structural. The chimney is not terribly tall but wind load is a consideration since the build is open dome.I only had one course of bricks over my anchor plate, I think JR had the same.

[fnbroken]

Cool, thanks Russell.

My inner vent has a 500m width, the outer vent is 680mm providing a reveal of 70mm between the two.

Is this either enough? Or too much?

I played with putting an extra course in, and it looks better so will have 2x50mm courses on top. Looking back, I notice that the holes in the lower course have been tapered to make it even smoother. Will do the same...

[UtahBeehiver]

I understand now, we are talking about the inner and outer arch sizes. 70mm revel will work fine. The outer vent arch just needs to be bigger than the outside size of the door frame so you and get it out.

BTW, Only if you want to install door stops, but they are typically self standing. The thicker the door the heavier it is so there are trade offs. Mine is on the thinner side at 1.5" with CaSi board inside. Some are going 3-4" for more insulation purposes but they tend to get heavy.

[fnbroken]

Sweet, thanks.

Re: doors. I've been looking at what can be cooked in the oven if the heat can be retained. Once I get a handle on that, and if it's likely something I will want to do, then this will probably drive the insulation requirements of the door. Will probably do like most and start simple and upgrade with time as required. It's really the core bits (those that cannot be upgraded easily later) that I want to spend the time and money on getting right now.

[fnbroken]

Extra course of brick on top of outer vent (total 3 x 50mm), with 'tapering' cutout (silver bit) that I will do to align the top of the serpentine arch to the diameter of the flue - hopefully ensure smooth flow of gases... I will also bull nose the bricks forming the inner arch of the outer vent going up into this area...

[Steady]

Enjoyed reading your thread just now fnbroken - looking forward to following the build

[fnbroken]

Thanks Steady - can't wait to get into it!

[philbo baggins]

Hey mate
I'm currently in the embryonic stages of doing a corner WFO. Will be refering to your post a bit. I'm doing a dome 36" .

[fnbroken]

Slowly getting towards having the site cleared ready for the foundation - painful when it rains most weekends - yet is beautiful and sunny during the week :/

David S - if you dont mind, a couple quick Q on the waterproofing product you use - Xypex - assuming it is the red one (ADMIX C-1000 NF):

- How much is a 15 or 20kg bucket?
- How much would you expect to use on a hearth slab (2000x2000x120)?

Many thanks

[fnbroken]

Wow...so many builds started and progressed so far...I've only been away for 3 months and so many threads to catch up on!

While i've been away I havnt been [completely] idle - I finished clearing the site for the WFO slab....and got excited and cleared the garden beds, pergola and 9 cubic meters of old concrete paths! Breaking them all up with a jack-hammer and carting it away wasn't fun :/

So today the concretors came and put down 112 sqm of concrete! The WFO slab is integrated - 2 layers of 9.6mm mesh in what worked out to be 200mm thick 32mpa concrete... no going back now!

Seemed more economical to combine the two projects and have it done professionally all at once - very happy with the outcome....

https://goo.gl/photos/RzNQAcsi9pvAZn8f8

https://goo.gl/photos/yZLULK6ANXjKKXAr9

Picked up a brick saw for $100 - needs some tlc, but will get me started with the besser block stand - want to cut top sections out to use as the form work for the hearth....

https://goo.gl/photos/jJWdQ6MoQXuDkFnQ7

Getting back on track.....

[fnbroken]

Links not appearing as photos - so tried again....

[Steady]

Your slab looks to have a nice finish

[JRPizza]

Nice job on the slab! I wish I would have had the foresight to go with a raised area like you did. When it rains a bunch (all the time) water pools up against my base due to the slight slope of the patio. A locally raised area would have taken care of my water problem.