Pizza oven !

I think I may have mentioned wood burning pizza ovens before... I have always been a fan of wood baked pizza, and the wonderful food that can be made in the Greek  ξυλόφουρνο (wood fired oven).  I've looked enviously at the one Jamie Oliver uses in his TV programmes.

Well, since we are anticipating some building work on our house which will involve demolishing the kitchen - what better time than to build an outdoor oven !  Now I now that BJM  has mentioned cob ovens in this thread, and has posted linkes to some construction videos here.  I have a lot more reading, video watching and planning to do yet !  But my plan is to go for something a bit more permanent than cob, with a brick built oven perhaps as a sort of barrel vault, possibly with a hydraulic lime render on the outside.

First small step today - I intercepted an old storage heater on its way to the dump, containing two dozen heat retaining bricks.  This should cover 0.75mx0.75m, making the perfect oven floor !

Watch this space (not too intently though, this is going to take a while !)

Don't forget to leave enough space around your oven for the seating - for when you invite all the HMLifers over for a tasting.....

Ooh, that is exciting Chilli Head. I would love to be able to cook a pizza without a soggy middle - I haven't yet figured out a way to do it in a fan oven. I never used to have a problem with gas.

freebird wrote:Don't forget to leave enough space around your oven for the seating - for when you invite all the HMLifers over for a tasting.....

So, it has begun. Today I cast the concrete slab for the foundation of our oven. It's 1.2m square, 125mm thick reinforced concrete. Well, when I say reinforced, I had a many years old clothes drying rack, made of ~6mm diameter plastic cloated steel which was beyond use in the conventional sense, which looked about ideal for the job. I squidged in at ahout half the full depth of the concrete.

I mixed the concrete by hand despite the wise suggestion from DW that it might be worth hiring a mixer. Now well and truly worn out !

Great recycling CH!

Ahem ..... no pics, it didn't happen (now who was it who said that?).

Ahem ..... no pics, it didn't happen (now who was it who said that?).

We'll put it down to the man flu......

Between the flu and the weather, my pizza oven project has been stalled at this point for some time:



But frustration got the better of me this weekend, and I did some bricklaying.  Got a few courses done before the sky ominously darkened - just as I'd tidied up it went very dark, then the hailstones started.  No picture of where I got to yet, I had to quickly cover it with bubble wrap to keep the frost off - wet cement and frost can lead to disaster.  Poking my nose under, it looks like the bubble wrap may have saved the day.

A few more bricks this Saturday.



This is the base, with a bit of storage space. The area in front and inside I'm going to pave continuously with the existing patio.

A couple more courses of the boring bit to do before the fun starts.

You can just see the remains of my overwintering cabbage behind. One hugely fat pidgeon has been strutting up and down the row puning them daily. It doesn't wait 10 minutes after I've gone before returning for another sitting !

I can see it's going to be a posh job. I'm interested in how you get on with the actual oven bit. Mr P's niece built one a couple of years ago after reading a 'Build yourself a pizza oven in a weekend' article. It took her 3 weeks of hard slog but fair play, she stuck at it and it was a resounding success. It ended up the subject of another online article (without the rose coloured spectacles).

Oooh, that's a nice looking bit of brickwork, CH.

It's a bit taller after the weekend. It is just bricklaying though, so not terribly green even if it is homemade ! It should start getting more interesting soon ...

There will be the odd bit more recycled ingredients, honest. I did do a little re-using at the weekend - the big spoil pile covering my veg plot is now gone - into a new raised bed my neighbour is making as a herb garden next to their patio. It more or less fitted perfectly. They got a bargin there - I manured this patch to grow the popcorn there last summer, so it is nice veg plot soil. I hope their herbs are not too spoiled by it !

Getting to more interesting bits now.  This is the base nearly done.  The slightly tatty looking slabs on the top are paving slabs reused from another part of the garden, where a pond / water feature will be going.  They won't be visible, so that's fine.  They're sitting on a concrete lintel acros those piers you can see in the sides of the base. The brickwork has a couple of courses to go yet; on top of those slabs goes an insulating layer, then the cooking surface itself.

I've made the paving run continuously under it; the new paving stands out a bit, even though they are the same type.  This area is meant to be for log and tool storage, but at the moment seems to be providing a cat shelter for the neighbours' moggy !  Might need to put a door on it, I think.

I can see from the beautiful finish on your brickwork that you and the family are not going to be puddling vast amounts of clay by wellied feet to cover a dome shaped thing.  That was the image that pizza oven conjured up for me.  It's looking great and we will, of course, need to see pictures of the first pizzas.
A door probably would be a good move as it could be a nice cosy refuge for all sorts of wildlife.

First time I've looked at this fred. What a lovely edifice! Looking forward to progress - and pizza

Ploshkin wrote:I can see from the beautiful finish on your brickwork that you and the family are not going to be puddling vast amounts of clay by wellied feet to cover a dome shaped thing.  That was the image that pizza oven conjured up for me.  

That is the idea I had in mind originally. I saw one built on TV - perhaps it was It's not easy being green - by making a mound of sand, covering with newsprint, then a clay layer, finally excavating the sand when it has set. Looks easy ... but, as I read more, it seemed to me that there were a number of drawbacks to this appealingly simple approach. It is very easy for the clay to crack in drying. And to work well, it needs to have enough floor area for cooking, and a lot of thermal mass. That means an awful lot of clay. Now, living in Bedfordshire but a few miles from Marston, clay is not hard to find. My garden is sandy, but the allotment is on top of heavy, yellow clay. But to excavate enough to make a worthwhile oven, and move it to here was going to be a lot of work.

Another problem is that the clay oven is not naturally waterproof. Options are to either regard it as temporary, or protect it from the elements in some way. Some websites suggested covering it with a tarpaulin when not in use - not aesthetically great ! The other approach is to build a permanant shelter / wooden structure around it - on another website one guy was saying his wife referred to what he'd built as his "pizza hut" - but that's also a fair amount of work.

Then I started thinking of the Greek fornos, usually large stone built structures, and the brick built Roman ovens. Then my inner engineer took over ! We are Mediterranean food lovers here, and a brick built oven will be more versatile, and (I hope) make a much nicer looking garden feature. The oven itself will be made of about half a tonne of refactory firebricks, which by my calculations will not only do pizza, but ought to stay hot for long enough for loaves, and long, slow cooked al forno dishes. Maybe even slow roast lamb a la Grecque

I'm just crossing my fingers I have got all my maths right. Or I'll be left with a rather unusual garden ornament

I hope we've all got an invite - I like the sound of slow roast lamb and freshly baked bread. I can provide a leg of home grown lamb.

I got time to do a bit more building today.  It's starting to get to the phase where I'm building parts of the oven, not just the stand !

A key thing for a pizza oven is being able to get a crispy base to your pizza. To do that, you need a cooking surface that gets hot, And holds its heat well.  That means insulation, which easiest achieved by trapping air. Googling yeilds a few ideas.  One is a stuff called vermicrete, which is basically a sort of concrete made with vermiculite as the aggregate.  I made mine with a mix of portland cement and the mildly more eco lime, which reabsorbs some of the CO2 released in its manufacture as it sets.     But still, it is an expensive and not greatly green material.  The second idea really appealed - especially since the local bottle bank is closed so I have to go out of my way to recycle glass:



I've selflessly emptied all those bottles myself.  These ones will be hidden by the rest of the vermicrete before the cooking surface covers it all - noone need ever know ...  I'll have to find something else to do with next week's empties.

You can also see some bricks cut at an angle, which are where the base of the vault of the oven is going.  Being an engineer at heart, this is not going to be a simple cylindrical barrel vault, but a catenary arch ... more later.

Chilli-head wrote:

You can also see some bricks cut at an angle, which are where the base of the vault of the oven is .

I do see the bricks cut at an angle ...... just assumed they were the result of imbibing the contents of all those bottles!

I've seen the bottle thing being done for floors for pig pens & the like. I'm looking forward to seeing the caternary arch (& the first pizza)

The finished vermicrete layer, with the final course of facing bricks around. Next step is the cooking surface.

Did a bit more yesterday, working on the main arch of the oven, for which I'm using an inverted catenary shape.  For the non mathematical, that is the shape a chain hangs in.  The useful  characteristic is that the chain hangs so that the line of tension runs along the chain - and simliarly in the catenary arch, the thrust passes down through the arch, with only compresision and no shearing forces on the joints. So hopefully, even if the heat causes the mortar to crack, it won't fall down !

To get the arch shape, I wrote a computer program that computes the catenary, then shrinks it perpendicular to the curve by half a brick thickness, to make the shape of the former on which the bricks rest.  Plotting the points on paper, then sawing wood to fit gives the former seen in the next picture:



Then it's simply a matter of bricking up around it.  This is as far as I got before the mortar, and my energy, ran out.  These firebricks are nearly 4kg each, much heavier than normal brick, and very hard to cut !



Just realised I missed a step; on top of the vermicrete in the last post, I layed the cooking surface.  This is where I used the reclaimed (aka skip dived) storage heater bricks.  I forgot to take a photo, but is is just like block paving.

That's looking incredibly impressive chilli head and I'm in awe of your catenary computing. All I knew about catenary curves is that bees build comb that shape (without a computer)

last few bricks in place.  The curvature is tighter here, so they needed cutting to shape. Former removed after a couple of days setting - and it stands self supported !



The gap at the top front is for the flue pipe.  That's going to be a bit of re-cycling that I'm particularly proud of. More later !