New build started in Scotland

[MarkJerling]

Good to hear. Sorry, on the photo, the flue looked hard against the ply. Good to hear you have it spaced.

[jjnevis]

Mark, it's a twin wall flue and the timber is all 50mm away from it. The only bit of timber I'm slightly concerned about is the bit directly above the center of the outer arch, but it didn't get above 50c on the full firing, and at no point did flame get anywhere near to licking out the front. I'm going to keep an eye on it and may still cut out some timber and replace with metal if required.

[MarkJerling]

OK, time for another update, mainly using photos. I've decided not to buttress the arch and hope for the best.

The narrow chimney opening seems to be working okay (as can be seen in the photos), I haven't got the oven up to temp yet, just on day 4 of curing fires at the moment, but pretty much all the smoke is going up the chimney, as least when there's very little wind. Trying to take the curing very slowly, being very nervous about cracking, but so far, so good although only at about 200 C at the top of the dome.

I'm also hoping for the best as far as insulating the heat from the wooden structure - there is as least 100mm of ceramic fibre blanket between the dome and any wood, so fingers crossed that will be enough, no calcs involved just hope. I'll keep an eye on any heat escaping out the front of the tunnel and may put a heat shield on to protect the wood above that, if required.

Planning on first Pizza party next weekend , hoping this amazing weather holds out!

I don't know if anyone else has mentioned this, and it might just be me, but I love the noise the oven makes when the wood crackles while burning, a kind of really soft deep popping sound

Wishing everyone doing builds at the moment good luck and courage, if required.

A question: Is that a dual wall or triple wall flue? If single wall, I'm concerned about the close proximity to timber. Even if it was a double wall, I'd still keep the wood a minimum of 2" (50mm) away from the flue.

[jjnevis]

Thanks NCMan, I'll keep and eye on things and there is a good spot at both gable ends if I think it needs a vent, which I can add later.

I've finally had it up to temp (over 400 C at the soldier brick surface) and whole dome went clear very nicely. Monitored the temp everywhere and all seemed okay.

[NCMan]

Thanks for the kind words. No, not planning on designing in any venting, the structure is not particularly air tight, so I'm assuming there will be enough ventilation through gaps etc, what do you think?

If it were me, I'd design in some type of venting. It's an inexpensive thing to do and it will help, especially w/the heat generated in there. W/your slate roof, it's probably best to skip a ridge vent, although, along w/a soffit vent, they are the best. Even a front and rear gable vent would be helpful, although it may be a bit late for a rear one. Just a suggestion. Looking forward to watching your progress!!

[jjnevis]

Looking good!! Are you planning on some type ventilation for the enclosure, such as a gable, soffit or ridge vent(s)?

Thanks for the kind words. No, not planning on designing in any venting, the structure is not particularly air tight, so I'm assuming there will be enough ventilation through gaps etc, what do you think?

[NCMan]

Looking good!! Are you planning on some type ventilation for the enclosure, such as a gable, soffit or ridge vent(s)?

[jjnevis]

Couple more photos...

Going to slate the roof next week, so I can add "roof slater" to my new skillset

[jjnevis]

OK, time for another update, mainly using photos. I've decided not to buttress the arch and hope for the best.

The narrow chimney opening seems to be working okay (as can be seen in the photos), I haven't got the oven up to temp yet, just on day 4 of curing fires at the moment, but pretty much all the smoke is going up the chimney, as least when there's very little wind. Trying to take the curing very slowly, being very nervous about cracking, but so far, so good although only at about 200 C at the top of the dome.

I'm also hoping for the best as far as insulating the heat from the wooden structure - there is as least 100mm of ceramic fibre blanket between the dome and any wood, so fingers crossed that will be enough, no calcs involved just hope. I'll keep an eye on any heat escaping out the front of the tunnel and may put a heat shield on to protect the wood above that, if required.

Planning on first Pizza party next weekend , hoping this amazing weather holds out!

I don't know if anyone else has mentioned this, and it might just be me, but I love the noise the oven makes when the wood crackles while burning, a kind of really soft deep popping sound

Wishing everyone doing builds at the moment good luck and courage, if required.

[Baza]

jjnevis Thanks for the kind words for a bloke winging it too!! Yes - the segmented arch (not a whole arch but one with straight sides as you and I have) appears to require thoughts around buttressing.

I’m going to - just to be safe. As I’m enclosing my dome in a structure (the aesthetic in me dies a little at the thought) the buttress won’t be noticed. But for those leaving an igloo shape I believe design elements of such a buttress should be considered.

mate - this is learning from lurking this forum - not experience. It could well be that you’ll be fine!

looking terrific!
Barry

[jjnevis]

Barry, thanks for the praise and constructive criticism and in response to all the questions and concerns over the functioning of the chimney all I can say is that I'm pretty much winging it and hoping for the best. The only actual "design" element that went into it was choosing a 6 inch internal diameter flue pipe based on a general consensus of flue sizes for a 34 inch oven. I'm sure it will puff out the front a wee bit at the beginning when lighting the fire which I'm not too worried about, but I hope that once the fire is going and the flue has warmed up then it should draw strong enough to pull the combustion gasses up the chimney. The throat is a little narrow, but the area of the opening is larger than the area of the 6 inch pipe so hopefully it'll work.

It hadn't even occurred to me that the arch might not hold the weight of the transition cast and the chimney, but now that you've mentioned it - I'm a little concerned!

I've had a quick look at your build - a thing of beauty! Your brick cutting and mortar joints are fantastic, well done. Looking forward to seeing your progress.

[Baza]

jjnevis - wow! Great progress.
Your chimney transition looks solid! I have fears of my own at this point worked about how much weight the arch can hold!
Looking at this ... apparently A LOT!

Wondering if your throat isn't a bit narrow?
Will the space draw well? I'm not critiquing - just wondering - I don't know the physics of this but I see other builds to inform mine and seem to come away with a wider at the bottom is better (to "catch" the smoke up the chimney?

Looking forward to learning more about your progress mate!!
Great pace!
Barry

[jjnevis]

Just some photos of how the chimney transition (as I'm calling it) turned out. It's difficult to get a photo that really shows how it's worked, but hopefully you can see from these that it has actually worked really well. Not the prettiest, but you won't see it anyway, so who cares as long as it functions correctly.

[NCMan]

That should do fine.

[jjnevis]

Decided to go with a concrete cast for transition to chimney. The form work was a real head scratcher, but in the end decided to just chuck gaffer tape and anything I could find at the problem, including a full roll of kitchen roll and an old sleeping mat chopped up. I think it should work ok and was much easier than trying to do it in brick. I also reinforced it so if it does crack, it shouldn't fall apart. The twin wall flue will just be mortared onto that.