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Post by gayterman on Jun 7, 2016 18:52:36 GMT
Hi all After years of talking about building a pizza oven, and not really having anywhere suitable to put it (at least that was my story!), my wife recently decided to chop down a large laurel tree, and hey presto, I suddenly had a gap where it would not only fit, but would also not look out of place. I have thus finally stopped being the butt of family jokes concerning non-existent pizza ovens, as work is at last under way! I'm using the freely available Forno Bravo plans (US), which are a godsend for someone like me who does not have much of a practical bent, but who is perfectly capable of following decent instructions. Not everything is in there of course, so some things have to be worked out on the spot, whilst forums like these are without doubt an invaluable aid. Three 'learnings' from this phase: - The US plans are massively over-engineered. Even to a novice like me, a concrete foundation with steel mesh AND two runs of rebar underneath where the breeze blocks would eventually go seemed like overkill. My building-trade mate asked me if I was planning to launch anything into a near-earth orbit or...! As I am clearly just aiming for pizza not a V2 test bed, the rebar was omitted.
- US concrete blocks (imperial units in the US plans) are not available in exactly the same size in the UK. The latter are slightly longer, so when I laid out five end to end (front to back of the build), it was touch and go whether they were going to fit on the already-laid foundation.
- Make sure your building supplier delivers concrete blocks (breeze blocks) from a single manufacturer. I dry-built the base and couldn't for the life of me work out why I was occasionally getting a step between breeze blocks after the first two courses. After scratching my head for an age, I finally decided to measure the blocks, only to find out I had three separate batches, they all looked roughly the same, and the vast majority were 215mm tall (all the ones on the first 2 courses), and then I had some at 210mm and the rest at nearly 220mm. This is probably not a problem if you are using cement, but in a dry-build it most definitely is! Cue much swearing and a lot of swapping of heavy blocks in and out to compensate.
Here are a few photos of this stage. Cheers, Ash
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Post by oblertone on Jun 8, 2016 6:54:14 GMT
Nice slab and acute observations: I used FB as a resource before I started my build and it's a great resource for sure, however I tend to agree regarding the over-engineered comment. There are some fantastic constructions detailed and one day I might get around to doing a dome where every brick is a trapezoid laid according to a spreadsheet, one day, maybe ...
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Post by gayterman on Jul 2, 2016 12:35:04 GMT
Really pleased to finally have all the shuttering and supports in place, especially as my woodworking skills are, shall we say, untested! Everything went really well bar a leg which I somehow managed to cut 20 cm too short, and in true conformance to Sod's Law, it was the last piece of wood I had (of that section). Managed to rescue the situation by packing it with offcuts. The only real surprise during this phase was financial - I hadn't realised just how much 2"x4" it takes, nor how expensive 16mm marine ply is. I have suspicion that the slab and supports are over-engineered (following US plans), but having said that, it is quite a wide plinth, and the firebricks themselves are far from light, so better safe than sorry I guess.
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Post by downunderdave on Jul 2, 2016 19:54:35 GMT
Removal of the form work is much easier and less likely to damage your slab if you have wedges under your uprights.
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Post by gayterman on Jul 5, 2016 20:01:39 GMT
Already poured the top, so guess that I'm going to have to find out the hard way! A few do have shims in, but the majority don't. Thanks for the advice though, I'll remove them carefully, with the aid of a saw should I meet much resistance!
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Post by gayterman on Jul 24, 2016 15:15:34 GMT
I've now poured the concrete plinth and covered it with a layer of vermiculite/cement insulation. Unfortunately, I got a bit carried away with the concrete and made it too deep, which meant that I only had 2.5 inches for the insulation instead of the planned 3.5 inches. I was tempted to wing it and leave it at that, but a quick trip round the internet made it fairly clear that skimping on insulation below the hearth could have disastrous consequences for the concrete beneath. Therefore, after a bit of head scratching, I added some battening to raise it up by another inch, which I'm sure the eagle-eyed will spot. I probably need to stand on tip toes now to get the pizzas in and out :-) Cheers, Ashley
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Post by gayterman on Jul 31, 2016 16:47:02 GMT
I ordered 230 firebricks (the number recommended by Forno Bravo) and 100 kg of refractory cement, both from PotteryPro of Newark (they are on eBay) which at just over a ton, set me back nearly £90 in delivery charges - fingers crossed that the quantities suffice. I decided to go for ready-mixed refractory mortar (£18 per £25 kg bag) as that seemed a better bet than mixing it myself, with lime, and to be honest, not that much dearer. Rather than go for a wooden baseplate for an indispensable tool, I've made up a 42" round template for the oven bottom, with a slot cut for an indispensable tool. I've taken a risk here by using polystyrene insulation board (dead cheap) as it's easy to cut with a hot knife, so am hoping it survives the rigours of the build without transforming itself into a billion polystyrene balls! I made the indispensable tool from a furniture caster, a piece of wood and a fencing 'z'-clip, following the instructions on a You Tube video; these were a god send, and made a job I was dreading, ridiculously easy. My guess is that lots of folks have used the same video, but in case not, here's a link: www.youtube.com/watch?v=oMf32antfNY. Once I had the template, I laid all the bricks out in a herringbone pattern, drew around the template and then cut the bricks to match the footprint, so that I used as few bricks as possible, but with the first course laid on top of the hearth. I also had a go at dry-building the oven opening, arch springers and arch, just to get the dimensions right. Next job is to lay the hearth on sand and fire clay, a bag of which I also got from PotteryPro.
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Post by gayterman on Aug 4, 2016 21:21:29 GMT
Some photos of the completed hearth, laid onto a layer of sand and fireclay, on top of the vermiculite/cement insulation. Struggled a little to get it level, so there are some irregularities, but nothing alarming. When the dome is done, I plan to carefully go over the hearth with fire cement to fill the cracks and generally smooth out some of the small steps between bricks. It took quite an effort with a spirit level and silicone hammer, one brick at a time, and with the benefit of hindsight, I do wonder whether it would have been better to lay five or six loosely, and then hammer them down using a large flat piece of wood to get a better level. No idea if that would have worked, but the inherent issue of laying one brick at time is that you inevitably introduce small irregularities in the level (side to side and back to front) which are difficult to discern, but which grow in magnitude as the bricks radiate out. Reasonably happy with the outcome though. Cheers, Ash
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Post by chas on Aug 5, 2016 8:03:21 GMT
Some photos of the completed hearth, laid onto a layer of sand and fireclay, on top of the vermiculite/cement insulation. Struggled a little to get it level, so there are some irregularities, but nothing alarming. When the dome is done, I plan to carefully go over the hearth with fire cement to fill the cracks and generally smooth out some of the small steps between bricks. Hi Ash, very neat start - and a look at the hearth pic large suggests you might dispense with the fill you're suggesting... grouting will almost certainly break up under the extreme heat and give you the chance of grit in you pizzas. Any gaps will soon fill with, well, ash - and that's preferable. Cheers, Chas
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Post by oblertone on Aug 5, 2016 8:40:57 GMT
If you're paranoid then you could go over them with an electric sander ( with either no paper or paper reversed ) which might help them settle; but don't bother filling gaps, as Chas has said, they'll fill with ash as soon as you use it.
Great start, keep the pics coming.
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Post by gayterman on Aug 5, 2016 11:13:58 GMT
Some photos of the completed hearth, laid onto a layer of sand and fireclay, on top of the vermiculite/cement insulation. Struggled a little to get it level, so there are some irregularities, but nothing alarming. When the dome is done, I plan to carefully go over the hearth with fire cement to fill the cracks and generally smooth out some of the small steps between bricks. Hi Ash, very neat start - and a look at the hearth pic large suggests you might dispense with the fill you're suggesting... grouting will almost certainly break up under the extreme heat and give you the chance of grit in you pizzas. Any gaps will soon fill with, well, ash - and that's preferable. Cheers, Chas Thanks Chas, the steps (between odd bricks) are fairly small, and I hadn't really thought about the ash, which as you say, will fill them up anyway, so probably no need to bother with fire cement :-)
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Post by gayterman on Aug 5, 2016 11:15:39 GMT
If you're paranoid then you could go over them with an electric sander ( with either no paper or paper reversed ) which might help them settle; but don't bother filling gaps, as Chas has said, they'll fill with ash as soon as you use it. Great start, keep the pics coming. Thanks, will add some more over the weekend, I'm actually about 5 weeks behind (pic wise), so will try to catch up, otherwise, folks' advice isn't going to be of much use if I've already done the next steps (wrongly)! Cheers, Ash
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Post by gayterman on Aug 5, 2016 11:30:52 GMT
A few more pics - have not been working through the night - just trying to catch up on uploading photos as the build is about 5 weeks ahead ;-) The first two photos are of the sides of the oven opening and the arch springers. I was in two minds about where the side bricks should start in relation to the dome footprint, but after looking at a lot of photos on this forum and Forno Bravo, I went for a straight, full kiln brick, effectively at right-angles to a horizontal line cutting off the front of the oven. Seemed like it would need less fancy cutting, especially as I don't have a jig. Managed to completely forget to soak the bricks, even though I knew this was essential, so was a little non-plussed by the speed (seconds) the mortar dried out! Fortunately, one of my offspring was on hand to point out that soaking the bricks might just help - doh! Last photo is the first course of the dome - half bricks laid on edge - a rare photo of me captured by my better half, who thinks I've been replaced by an alien after 30 years of never building anything! The beanie is Derbyshire Scout Caving Team, some skills I'll no doubt be calling on later on when I have to get through the oven opening to tidy up the dome inside! Cheers, Ash
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Post by gayterman on Aug 7, 2016 15:40:53 GMT
A few more photos of the dome construction. Rather than cut precise wedges, I just used kindling, relying on the Indispensable Tool to give me the correct inclination. On the first inclined course (the second course) I went around the entire circumference with these (see first photo), in the process discovering that they are easy to knock (and thus disturb the carefully laid brick) and subsequently, when the cement has dried, they are not always easy to get out! For the third course, I used three wedges, cycling around, taking the first one carefully out when I got to the fourth brick, and then back-filling the hole. This worked a lot better than the first method (IMHO). The last photo shows the completed third course up to the arch springers, the next job being the arch itself, which I was not particularly looking forward to.
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Post by keithw on Aug 8, 2016 11:06:02 GMT
I am very interested in this build as it is basically what I am planning. I would be interested to know your suppliers and costs as well as approximately where you are in the UK. The Build looks great and I hope mine turns out half as nice. What size would you make your slab in hindsight now that you know about the concrete block size difference?
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