30"/760mm Scotland Pompeii

[jms]

I've been lurking for a long while and I've finally got time to do my own oven project. The FB plans and peoples' build threads have been invaluable during my own planning.

The plan is for a 30", no-vermicrete oven, which will be finished with a brick outer-igloo. Several years ago I built a clay/sand oven which was compromised from the start by the habitual dampness of the scottish weather, so with this build I'm trying to avoid things which the weather might complicate.

I finished the plinth nearly two months ago. Available space in our garden was an issue, which is the reason why the oven will be so small compared to some of the behemoths on here, but 30" will be plenty big enough for our use of small pizza-parties, bread, and roasts.

A tree (fatally damaged in a storm) and the old oven used to inhabit the space where the plinth is. The tree needed to come out eventually so we took the opportunity to take its roots out too and then turn the resulting hole into the foundations.

[jms]

Re: 30"/760mm Scotland Pompeii

Moderation queue took a while

The old clay oven remains were originally going to be disposed of elsewhere but then I realised that I'd need to fill in the first two layers of blocks to make a floor for the wood-store. The amounts lined up pretty perfectly. Layer of sand on top and then concrete.

Next day I filled in the surrounding voids with rock and then continued stacking the plinth blocks and filling them with concrete.

[boerwarrior]

Re: 30"/760mm Scotland Pompeii

Looking good, jms!

I built a 32inch - and I am extremely happy with it!

My thread is here:
http://www.fornobravo.com/forum/f8/3...nia-19283.html

Good luck and don;t hesitate to ask questions!
Neil

[EddiePJ]

Re: 30"/760mm Scotland Pompeii

Fair play to you, that is alot prep work to get out of the ground.

Nice to see Scotland with some sun.

[jms]

Re: 30"/760mm Scotland Pompeii

I ordered a reinforced concrete lintel to span the wood-store from my local builders yard. Unfortunately at the time I didn't know that they could make them to pretty much any size, I had ordered a preset size, so I had to cut it down with an angle grinder. Mortared the lintel down and then built the framework for the top slab.

Once I had the framework up I cut my steel mesh reinforcement. I had a lot extra so I overlapped it quite a bit. Finding the little plastic holder-feet things I've seen in many US builds proved to be impractical, I found that in the UK you can only get them in boxes of 1000 , so I had to use some treated timber.

[mrchipster]

Re: 30"/760mm Scotland Pompeii

Finding the little plastic holder-feet things I've seen in many US builds proved to be impractical, I found that in the UK you can only get them in boxes of 1000 , so I had to use some treated timber.

Sounds like a business opportunity buy the big box, repackage and sell them to small hardware stores. Next time use a small piece of Brick or stone for your rebar chairs when in a pinch.

[jms]

Re: 30"/760mm Scotland Pompeii

I dismantled the slab framework after a week because I knew I couldn't do the next stage for at least a couple of weeks so there was no rush, the extra safety couldn't hurt.

In all the plinth consumed around 70kg of cement, 200kg of sand and 300kg of aggregate. Shuttling the materials through our garage into the garden was probably the most time consuming part.

I'm pretty pleased with the result. I'm not yet decided on how it'll be finished, probably a basic render of some kind.

[jms]

Re: 30"/760mm Scotland Pompeii

Sounds like a business opportunity buy the big box, repackage and sell them to small hardware stores. Next time use a small piece of Brick or stone for your rebar chairs when in a pinch.

I could have cut up an old brick paver to use as chairs, but it didn't occur to me until just after I had poured it

[boerwarrior]

Re: 30"/760mm Scotland Pompeii

What are you going to use as underfloor insulation?

[jms]

Re: 30"/760mm Scotland Pompeii

Nearly a month ago I got around to ordering the oven materials. I used http://kilnlinings.co.uk who do everything needed. I originally wanted to get the stuff from a local supplier but they were ~25% more expensive.

At some point during ordering the Calcium silicate board got deselected and I didn't notice, which lead to a nice surprise upon delivery . The local supplier had some in stock and I picked it up the next day.

[jms]

Re: 30"/760mm Scotland Pompeii

What are you going to use as underfloor insulation?

100mm/~4" of calcium silicate board.

[Gulf]

Re: 30"/760mm Scotland Pompeii

Sounds like a business opportunity buy the big box, repackage and sell them to small hardware stores. Next time use a small piece of Brick or stone for your rebar chairs when in a pinch.

Or you can strategically place the first few shovel fulls of wet concrete. Then pick the grid up to the level that you want .

[boerwarrior]

Re: 30"/760mm Scotland Pompeii

Perfect! I assume that is two layers - so make sure you stagger the joints and/or lay the boards lengthwise and crosswise...

[jms]

Re: 30"/760mm Scotland Pompeii

Perfect! I assume that is two layers - so make sure you stagger the joints and/or lay the boards lengthwise and crosswise...

Yep, two layers. I've had a mock up of my plans in sketchup so I can keep track of sizes and such.

I've got some slightly thicker bricks for the floor (76mm/3" vs 64mm/2.5" for elsewhere) so I can have some more thermal mass considering I'm not using vermicrete.

I'm still confused by the arch/dome transition. I've probably read through every search result on it and I think I'm more unsure than I was at the start .

[boerwarrior]

Re: 30"/760mm Scotland Pompeii

I'm not sure I understand your comment "more thermal mass considering I'm not using vermicrete" ??? Vermicrete is an insulator (not a great insulator but an OK insulator - your CalSil board is much better). Therefore it plays no role in the thermal mass of your oven. It's fine to have a bit more mass in the floor - it will take slightly longer to saturate it with heat but that shouldn't be an issue.

Wow, your sketchup skills are fantastic!

My only comment based on your drawing is that your arch appears to be a little too far forward. That is going to cause some weird gaps in your dome-arch transition near at the top of the arch. I wish that I had built my inner arch about an inch or two further back. In my opinion it is easier to fix transition issues when the dome is too far back rather than too far forward - unless you can design it perfectly before you start like some of the pro's on this site!