Build started in Mountain Top NSW

[shanesmith80]

Very neat job on the vent.

Where did you get the refractory glue?

[UtahBeehiver]

Nice job on vent stack.

[Gretsch]

Finished the entry arch today, didn't take too long, I did it in 2 stages.

First I built the two closer arches with a 15mm gap between the dome to allow me to stuff some fire rope between the arches, then I cut some slices of insulation brick and placed them between the two floors with a couple of mm top clearance to allow a strip of stainless steel to sit on top.

As I have a good half a bucket of expensive refractory glue I decided to use it. Maybe it's my imagination but it seems to be thickening as time goes by, so I had to squeeze the bricks really hard and carefully tap them down to get the required 2mm or less glue thickness. This made some previous joints move so I had to push even harder to try and get all the joins to close up. When the arch was finished I noticed it bulged out a bit, maybe 10mm on one side, the bricks no longer touched the template. Ah well, I don't think it's going to collapse, the next day it stood on it's own and the glue seems to really stick and hold tight.

I have a stash of pressed red bricks that I pulled up some time back that I'd been saving for this project. They were used as paving so there was no mortar to clean, just needed a good scrub to get the moss and dirt off. I wanted to keep using the refractory glue so each brick had to be cut to size. I really prefer this over mortar joints I reckon it looks nice and definitely won't crumble. I glued the back face to the fire bricks, (hope it holds) did a quick stack up to gauge the key stone then proceeded to glue and stack. Job done and I'm liking the look

I've also got some left over 400x400 glazed porcelain tiles, a charcoal grey colour that looks a bit like natural stone sitting next to the dome, reckon I might use them. Then I'll source a bit of granite to stick down on the entrance to save the floor brick edges from getting damaged.

Next I wrapped the fire blanket around the dome, got one layer around the bottom half and 2 layers on most of the top. Tomorrow I'll have to take a 400km round trip drive to get another box. That's the disadvantage of rural living.

[Gretsch]

I strongly support procrastination as it allows you to fully appreciate adult beverages...

That’s my excuse and I’m sticking to it
Cheers Mike

[SableSprings]

Your layout looks good and your plan seems pretty sound to me. My outer chimney arch and outside smoke chamber section are built with house brick and I've not had any issues...so far

Since you've corralled the insulation bricks, shifting should not be a problem. A layer of fire clay and builders sand to level the house or fire bricks will be all you need...they won't be going anywhere. I strongly support procrastination as it allows you to fully appreciate adult beverages...

[Gretsch]

To clarify, theres three arches apart from the inner most. Ill be leaving a 15mm gap between the dome (and its arch) and assemble the three arches (inner one, chimney arch and decorative house brick outer arch). The first two will be sitting on the insulation bricks. I know they wont get really hot but because its standing on its own I just feel I need to secure it down.

I've seen others use a piece of metal between the dome and outer floor as a heat break, I can't imagine it would stop heat flow. As you mentioned, the heat break is more about expansion joints rather than heat loss so that shoots my theory down.

I'm mortaring a row of house bricks around the insulation bricks to stop them possibly moving and I intend on mortaring the outer decorative arch bricks on this outer most row of house bricks. There is one concern and that's the house brick row is part of the of the chimney, although it's the outer most row I don't think it's going to get a lot of heat on it.

So I havent used any mortar or glue on the insulation bricks and am hesitant to do it. Maybe just a layer of fire clay and sand will suffice. Hope that makes sense, the picture shows the layout I'm considering.

Maybe I'm procrastinating

[SableSprings]

I mortared my outer arch down since I did not expect those bricks to experience any major expansion/contraction from heat swings. As David S has noted, the heat break that some install is more about providing an expansion joint than making a significant impact on heat loss. I'm a little unclear by your post if you mean the primary arch (closest to the oven-since that's where I see the insulating bricks) or the actual outer arch (farthest away from the oven).

My advice for you is to look at your oven in terms of expansion/contraction. The dome usually is 1) just outside the cooking floor (so both have "room to grow") or 2) the dome is on top of the cooking floor so shifting of the dome and cooking floor doesn't affect structural integrity. In reality, the curing of the oven will create it's own expansion joints as needed...the cracks . But because of the dome dynamic engineering strength, these cracks rarely (if ever) cause a structural failure. In fact, many old time bakers relied on the appearance and changes in their oven's cracks to judge the oven's readiness. Mortar down as you feel appropriate...you've developed good instincts during your build and review of the forum...relax

[Gretsch]

Another question.
Is the outer arch fire bricks mortared to the insulation bricks or not ?
the outer most bricks will be house bricks and will extend to the concrete slab so I think they will be mortared down.

[Gretsch]

Thanks Mike, you've confirmed my line of thinking.
I was going to try for a narrow chamber for easy access but now that you've mentioned the fact that flames will get past I'll stick with the 400mm depth I sketched up.
Looks like I'm on track but can't see that finish just yet. At least the hard yard is behind me now

[SableSprings]

Extending out with some remaining insulation blocks and using some building bricks as a barrier/retainer should work well. My philosophy was firebricks on anything close to the fire,,,so using them as the inner half of the arch/smoke collection chamber makes the most sense to me. I switched to house/red bricks on the outside half of my arch and have not had any problems.

I do think it's important to make sure your smoke collection chamber deep enough so that any flame coming out of the oven opening flows up smoothly and into the chimney without hitting the front arch inner surfaces. If I had to do it over again, I'd deepen my chamber to 10 or 12 inches (25-30 cm). Currently, I do get smoke escaping out the front because my smoke collection chamber isn't quite deep enough and a bit too tall (although when everything's heated up, the chimney draws pretty well).

I just built my inner vault arch without any fancy cuts...I was more concerned with stability and strength than making it "pretty". I knew I was going to be covering this "joint" against the dome with insulation (mine's perlcrete), so there's lots of ugly brick and mortar work hidden inside the oven's outer facade.

Looks to me like you've developed a good feel for how to make things go together...(Like my Brother-in-Law says, It's like putting socks on a chicken, sometimes it just takes a little more effort to get things to fit )

Great job on this Gretsch...you're heading for the finish line now!

[Gretsch]

I'm debating how to start my outer arch and chimney structure and have some questions.

Thinking of extending the insulation layer out about 250mm and then continue out further by mortaring some building bricks onto the slab to act as a retainer for the insulation bricks.

I assume fire bricks is the go leading up to the dome to handle the heat, house bricks could crack, definitely fire bricks for the arch against the dome arch and chimney structure.

Would house bricks handle whatever heat gets past the chimney stack for the outer arch ?

I've seen two methods of assembling the first arch, one idea was cutting an L in the bricks to follow the outside of the dome arch, is there any real advantage other than just a gap ?

[Gretsch]

Maybe ugly was being a bit harsh... let's say character.

[SableSprings]

You've done a great job on this Gretsch! As Russell alluded, from a structural point of view, pointing small joint gaps really isn't worth doing (unless you just can't personally stand it ). Also, as he noted, people never complain or frown about the mortar drips on the dome walls...they only see the bubbling cheese & meat on the pizza.

The words ugly & authentic can be substituted in almost any statement. It just depends on your attitude and perceived social pressure...relax and enjoy a job well done (and an oven that WILL work fabulously!) Lots of smiles from friends and family in your future

Looking forward to your completion of the arches & smoke vault/chimney so you can get to cooking!

[Gretsch]

Thanks Russell, yes it’s a good feeling at the end of the most important stage, I have scraped a fair bit of excess mortar off, the remaining bits have gone really hard and they’re not coming off without a fight so maybe they’ll stay.

the small gaps are quite shallow where the glue or mortar didn’t quite push through so it’s debatable wether it’s worth the effort. I’ll tackle the drip marks with some vinegar and a stiff brush, they do look ugly.

[UtahBeehiver]

Congrats on finishing the dome. It is a nice feeling......... The mortar joints look good, maybe a little tuck and pointing if you are so inclined.The removal of the excess mortar may not be worth the effort, no one but you will even know about excess or small mortar gaps. Very few people who have seen my oven stick there head in there especially when it is fired up...........LOL.