High Peak Pompeii Oven build

[gayterman]

Aug 8, 2016 11:06:02 GMT keithw said:

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?

Hi Keith, I'm near Buxton (in the Peak District).

My concrete base was designed for four 16" blocks across and four-and-a-half 16" blocks deep (Forno Bravo plans are of course from the US and therefore everything is in inches). My block work stand was a dry build (no mortar, just re-bar in every other block hole and then filled with concrete), so no gaps between the blocks (this made building it really easy for someone like me with no 'previous'). I then added on a few inches all around (more at the front in case I ended up facing with something more substantial than render) to support whatever I end up putting on the outside - this made for a base 75" wide, and 86" deep. The issue was that blocks in the UK are not 8" x 16" (as they are in the plans) but are metric, 210mm x 440mm, which is actually 8.26" x 17.323". So, where I was thinking that four-and-a half blocks in length would be 72", giving me 14" to play with at the back and the front, it was actually 4.5 x 17.323", which is 78", robbing me of 6" in one fell swoop. Not a disaster by any means, but one of those little surprises you can do without!

I got my breeze blocks, cement etc from a local builders' merchant, but went to a specialist for the kiln bricks, refractory cement, fireclay and ceramic insulation blanket. This was Pottery Pro, who you can find easily on eBay - they were really service minded and I would not hesitate to go back to them. I think the parent company is called Studweldpro-UK, and they are based in Newark, Notts. At just over a ton, I paid for it to be delivered, and it came to £671. That of course doesn't include all the locally supplied stuff (breeze blocks, cement, 'dust', rebar, angle iron etc.), a tidy sum in its own right. As my mates frequently say, "you could have bought a lot of take-away pizza for that", though they are of course, spectacularly missing the point ;-)

[keithw]

Good information, thanks. I can't wait to see more progress. How accurate would you say the BOM from FB is, I don't want to order more materials than I need particularly when the fire brick and insulation is so expensive. I am looking for ways to cut cost without compromising the final result. 

[oblertone]

Looking to reduce costs ?

Then don't use firebrick, use common red building bricks, preferably recycled. Sorry to be blunt, but I see so many builds starting off with a hefty bill and then only getting used 4-5 times a year. If you are starting a commercial enterprise and your WFO will be in use all day every day then by all means use firebrick; but if it's a home oven for casual use then common red bricks will survive perfectly well.

nb: Don't use ones with holes in them, indents are acceptable, but not holes.

[keithw]

Aug 9, 2016 18:58:05 GMT oblertone said:

Looking to reduce costs ?

Then don't use firebrick, use common red building bricks, preferably recycled. Sorry to be blunt, but I see so many builds starting off with a hefty bill and then only getting used 4-5 times a year. If you are starting a commercial enterprise and your WFO will be in use all day every day then by all means use firebrick; but if it's a home oven for casual use then common red bricks will survive perfectly well.

nb: Don't use ones with holes in them, indents are acceptable, but not holes.

I appreciate the suggestion, I concidered using red brick but then thought how much would I actually save that way and, more importantly, how much would it effect the performance? I imagine Pizzas would be every bit as good but I would like to use it for roasting Chickens and maybe a Turkey at Christmas as well as bread and pulled pork or whatever. Chances are I would use it a lot more for just pizza but I think I would kick myself if I compromised and limited what I could use it for. I would rather just try to save as much as possible by working out whether an extra thick layer of Vermicrete (or whatever it is called) is cheaper than fire blanket or if I can use Aerated Blocks instead of Calcium Silicate without affecting performance and calculating exact material quantities beforehand so I don't order too much and shopping around for the best deals. I think I can forgo the rebar and just use cheaper wire reinforcement in the Base and Hearth.



I make Pizza's virtually every week so I am sure I will use it more than 4-5 time/year.



My main goal is to make a top notch oven, if that means I cannot save any money then so be it, I just dont want to waste money unnecessarily.

[gayterman]

Aug 8, 2016 21:24:51 GMT keithw said:

Good information, thanks. I can't wait to see more progress. How accurate would you say the BOM from FB is, I don't want to order more materials than I need particularly when the fire brick and insulation is so expensive. I am looking for ways to cut cost without compromising the final result. 

Hi Keith

I would say that their quantities are reasonably accurate, though some things (like rebar in the base) seem like overkill. For the 42" oven, FB recommended 230 fire bricks and 200 lbs of refractory cement. I've just completed the dome and arch, with the chimney base still to build, and have 24 bricks left. There's been quite a lot of attrition from bricks not breaking cleanly, mainly due to the nightmare I've had with diamond cutting discs, or should that be 'non-cutting discs', which inevitably led to me trying to bolster bricks that hadn't been cut deeply enough, with predictable results. This is a saga in itself, which I guess I need to write down here eventually. Whilst the number of bricks seems about right (230), the refractory cement most definitely wasn't - I've not been ultra careful, but neither have I been profligate, yet I reckon I will be closer to 150 kg, which is well over 300 lbs. That was two re-orders of 25 kgs, each costing a tenner postage.

With respect to using standard red bricks, I'm sure this would be a big cost saver, especially if you can get them cheap or totally gratis. I plan to face my arch and supports in reclaimed brick, of the hand-made variety, which I obtained from a local reclamation dealer, and for which I had to pay £1 a throw, so two-thirds of the cost of a brand-new fire brick. If you are happy to use modern machine-made bricks, then doubtless they can be had much cheaper. Part of my decision-making in using fire bricks was that I've never done anything like this before, it takes a considerable effort, and I therefore wanted to do it right. I did wonder as well, whether red bricks would result in some interestingly crunchy toppings ;-)

Cheers, Ash

[gayterman]

Here are some photos of the arch build, which I approached with a good deal of trepidation, but which turned out not to be that bad in the end. I made the arch former from an old Bushboard kitchen top, cut to shape, and sandwiched together with polystyrene (see first photo). Although it was fairly robust - in terms of load bearing - cutting four identical pieces of Bushboard and eight pieces of polystyrene was a whole lot trickier than I'd bargained for! However careful I thought I'd been, there were irregularities on the top surface which meant that the bricks did not lie as smoothly as they should have done when laying the arch - I would definitely not recommend this approach to anyone! When I get around to the red brick facing, I will definitely go for a plywood arch former.

For the arch itself, I used fire bricks on their sides (so 4.5 ins tall and 2.5 ins wide), and I did not attempt to taper them, instead relying on the arch for the correct angle and filling between each with refractory cement. The total depth of the arch is 1.5 fire bricks in length (= 14.25 ins). The arch is eight fire bricks wide, with a key stone in the middle. I have to admit to not really thinking the latter through until I came to cut it, only then discovering that the gap was wider then a single fire brick on its side. In the end, I used a fire brick laid flat (so 2.5 ins tall and 4.5 ins wide) which I then tapered to shape with the cutting disc. Inevitably, it's only half the height it needs to be, so another needed to be cut to lay on top (back and front).

I also built a chimney vent into the middle, which is half a fire brick deep (= 4.25") and two fire bricks wide, plus the width of the key stone (see last photo), so about 8 ins. Overall, I'm quite pleased with how it has turned out, but am annoyed about the former, as more time here would have avoided a lot of fiddling with bricks which did not lie flat and true on the 'irregular' arch.

Cheers, Ash

[keithw]

Thanks Ash, Interesting that the plans are so far off on the mortar I am weighing up using Homebrew instead. The arch looks good despite the issues you encountered and the dual keystone is actually quite effective looking if you weren't planning on facing it with your reclaim bricks.

[daibaker]

Hi Ash,

I'm interested in your choice of fire cement, I am thinking about going the same way and getting ready made, but the stuff i've just been looking at in Pottery Pro (25KG PROSET 2 FIRE CEMENT) says max joint thickness 1.5mm - 2mm, is that the stuff your using? are you shaping your bricks or just using halfs? the other option i've seen is Screed from Vitcas that says it will fill gaps above 15mm. I'm very confused.


Great looking build so far by the way.

Dai

[gayterman]

Aug 11, 2016 14:47:20 GMT daibaker said:

Hi Ash,

I'm interested in your choice of fire cement, I am thinking about going the same way and getting ready made, but the stuff i've just been looking at in Pottery Pro (25KG PROSET 2 FIRE CEMENT) says max joint thickness 1.5mm - 2mm, is that the stuff your using? are you shaping your bricks or just using halfs? the other option i've seen is Screed from Vitcas that says it will fill gaps above 15mm. I'm very confused.


Great looking build so far by the way.

Dai


Hi Dai


The stuff I got from PotteryPro comes in 25kg bags and is dry, you just had water. If memory serves, you can't find it on their eBay pages at all easily, and I only noticed by chance on one of their fire brick or insulation pages, that they say "we also sell refractory mortar". When I tried to find this again, I couldn't locate it. According to the invoice it's 'Intoval UK 1400 Gun - Procast 1400 GM'! It's quite coarse, but I've been happy with it. At £18 a bag (plus delivery) it doesn't seem that much more than mixing your own. Suggest you just call them or email them. The last bag I had was three weeks ago, so they definitely still sell it.

I finished off the inside (tidying up) with standard 'ready to use' fire cement (Ever Build XL) from the local builder's merchant.


Cheers, Ash

[gayterman]

A few more photos taking the build up a course or two, gradually making the intersection with the arch. I had been laboriously chocking each fire brick with a piece of wood (kindling) then filling underneath with mortar, but half-way around I switched to laying a bed of mortar then hammering the brick down with a silicone tipped hammer, just using the Indispensable Tool to get the inclination, and the mortar to keep it at the required inclination. This was a lot less fiddly, and I reckon about three times quicker! The intersection with the arch could have done with more care, as I didn't cut the bricks precisely enough so they don't follow the course level as accurately as they should. I probably should have cut replacement bricks when I realised this, but I was having such a nightmare with the cutting discs that I left them as they were. This has had consequences for the concentricity of the courses (for want of a better word)!

[keithw]

Its looking good, keep the pictures coming. I've changed my plans somehwat, I have decided to try to build a Neapolitan style oven with a lower dome height. I think this might be more tricky to build but I like the look and they supposedly make better pizza according to some people, I'm not sure I believe it makes that much difference but I like the idea of the flue laying over the of the oven to come out top of the dome.

What are your plans for the outside? are you going and keep the dome shame or box it in with brick? Have you any intention of sheltering the oven?

[gayterman]

Aug 13, 2016 11:18:40 GMT keithw said:

Its looking good, keep the pictures coming. I've changed my plans somehwat, I have decided to try to build a Neapolitan style oven with a lower dome height. I think this might be more tricky to build but I like the look and they supposedly make better pizza according to some people, I'm not sure I believe it makes that much difference but I like the idea of the flue laying over the of the oven to come out top of the dome.

What are your plans for the outside? are you going and keep the dome shame or box it in with brick? Have you any intention of sheltering the oven?

Hi Keith

I'm planning to render it and paint it in Sandtex or something similar, so it will be white or cream, but with a red brick arch and a red brick chimney (just the upper three courses). I have however started to wonder whether the arch is up to the job of supporting 7 courses of brick and a clay flue liner (that's quite a lot of weight). The rear of the arch is pushing down onto the springers (compression), which are held in place by the intersection with the dome, so I'm reasonably confident that it isn't going anywhere. The front is another matter entirely, as all the weight is basically going through the top springers, with nothing other then cement to stop them moving outwards. I'm therefore thinking of adding another column of bricks as a brace, however, I don't want to make the whole front wider, as I really like the plain white dome and red-brick arch look. I'm not a fan of the big boxed in ovens (personal preference) so really want to avoid building outwards if I don't need to.

I quite like the Neapolitan shape, but didn't dare try it. Good luck with yours. I reckon the key to success is religiously cutting each brick to shape, and knowing what that shape should be for each course! Not easy, but perfectly do-able with planning and patience.

Cheers, Ash

[keithw]

I wonder if you could drill down through the sides and and put some rebar and cement.

[bry]

I have the same debate going on in my head was going to have a double skin outer arch entrance to support a reasonable size chimney but only really have room for one skin and don't want to just stick crap on the side to brace it, decisions decisions...

[gayterman]

Aug 14, 2016 18:17:34 GMT keithw said:

I wonder if you could drill down through the sides and and put some rebar and cement.

Good suggestion Keith - thanks. I've just ordered a tungsten-tipped, long-series drill bit (20 mm x 200 mm) and will be chasing my mate to borrow his SDS hammer drill. I have some rebar left-over from the plinth so that should do the job. Having said that, the supporting tower of half bricks I put up yesterday seems really solid. Still, better safe than sorry I guess.

Cheers, Ashley