Thread: Building a pizza oven

^^^^, ^^^, ^^ & ^

Thanks guys, much appreciated.

Originally Posted by pseudolus

This is one serious project for a bit of pizza!

Yes, ridiculous really given we have a perfectly reasonable oven in the kitchen, but things just got a bit out of hand.

The intention at the outset was a mud oven like Nawty's.

OK, moving on a day or so, the outline of the terrace is beginning to make itself apparent:



A bit of a close up of the pizza oven base:



I made a bit of a departure from the Forno Bravo plans which leave the area under the slab that the oven sits on completely open. In the US they use the larger sort of double-walled cinder blocks that you can pour cement into to bind them together - these things:



We just used the normal skinny Thai ones so I had the guys build a wall under in the recess under the oven running from side to side and about half way back to give a bit more support. We then subdivided the back part in a similar way so the rear was quartered.

In the plans the area under the oven is meant to be a wood storage area, though my guess is that if we were to use it as such in Thailand someone will eventually be bitten by something nasty so there's nothing lost in reducing the area available under there.

Another view of the slab for the oven to be built on being prepared. From memory this was about 4 inches thick, again plenty of rebar.

I'm rather touched....never been an insper....inspa....inspo....role model before

Originally Posted by Nawtier

I'm rather touched....never been an insper....inspa....inspo....role model before

I'm sure you mean in a positive way......I'm sure you've been an inspiration to many in other ways...

This pizza oven is better planned than my house and a much better construction. Anyone planning on building here should start with a pizza oven and build outwards.

As mentioned, I was sort of winging this as far as the design went and a lot of stuff was being marked out with sticks in the ground that were subsequently pulled out to stir cement, throw at dogs or whatever.

I was away for the afternoon when they started on the steps, and by the time I'd got back they were too far into it for me to be able to change things that much:



So the issues were:

1) I would have like them angled more towards the centre of the terrace. Minor issue but I'd imagined them that way.

2) The pillars at the top of the stairs are too high. They made them by burying a concrete pipe then filling it with cement, so cutting through them, whilst feasible, was going to be something of a pain and wasn't worth the bother

3) OK, the last bit, and bear with me whilst I try to explain this.

The actual steps will have paving slabs on them, so the stair riser (the brick upright bit that they have just built) will have some paving slab in front its lower part that forms the stair tread (the horizontal part) of the step below. Effectively this means that each brick riser is only 3/4s exposed. The distance between the stair treads will remain as one brick high, except for the bottom one which, as they did not cut the brick down a bit, will be one brick and the width of one paving slab high.

The terrace floor was meant to be at the same level as the concrete foundation running along the bottom of the lower step.

The only option was to raise the floor level of the terrace a bit, but there were two problems with that.

Firstly it would mean that the bases of all the cabinets would need filling in with cement by a few inches to ensure that water did not pool in there. Not a big issue in itself.

The second issue was that the height of the oven, and indeed the cabinets, was meant to be a certain distance from the floor. It was now a certain distance less a couple of inches which annoyed me greatly as this was exactly what happened when they poured an especially deep slab for our house and left me with kitchen counters about 75 cms tall...

Anyway, it is what it is, we move on.

Originally Posted by bankao dreamer

This pizza oven is better planned than my house and a much better construction. Anyone planning on building here should start with a pizza oven and build outwards.

Hello BD - I know you sold your house last week but careful what you say until you know that the cheque has actually cleared...

I put a lot more thought into this that I did the house simply because I was planning to build the oven myself and wanted to make sure that if it was to collapse it would only be through my workmanship and not that of whoever made the base. I was also on site for this (for much of the time) which I think helped.

Have you thought about getting some electricity out to the site.


Sala, oven/fireplace, romantic bug zapping lighting would be nice....

^^
The cash is now in my bank oh deap joy. But still living here rent free your pizza oven in its infancy is a wonder to behold

Originally Posted by bankao dreamer

your pizza oven in its infancy is a wonder to behold

I would be bold enough to correct you sir, to "creating a pizza oven respite..."

Well, at this point in the tale the only thing wafting on the breeze is the faint smell of last night's Lao Khao emanating from the building crew.

Whilst it lacks the romance of gently roasting mozzarella it is at least the smell of Thai progress, albeit progress that is slow, often tangential to the plan and generally rather haphazard.

It won't be the same in Belgium BD, you'll miss it you know...

I will miss it in a way but by your inspiration I now intended to construct a pizza oven of my own in the garden of the small chalet in Belgium we have just made an offer on.

Originally Posted by CSFFan

Have you thought about getting some electricity out to the site.


Sala, oven/fireplace, romantic bug zapping lighting would be nice....

Yup, it's on the cards. There's some lighting for the steps going in (just visible as the blue box on the side of the steps in the photo above with the guy sorting the rebar out on the oven base) and we'll need a few power points and general lights out there. Candles and stuff are all very well but a bit ineffective really.

Originally Posted by bankao dreamer

I will miss it in a way but by your inspiration I now intended to construct a pizza oven of my own in the garden of the small chalet in Belgium we have just made an offer on.

Good man BD, that's the spirit!

OK, so next up looks like its been taken from the upstairs bedroom or bathroom.

The concrete slab on top of the pizza oven base has been poured.



You can see the rather convenient 'grassline' that was part of the inspiration for building this thing, saves planting and watering yet more grass.

... and then the morning peace was shattered:



Mr. Chaang sneaking in a crafty nip of something on the top left of the photo under the steely gaze of his missus and her friend.

Down at ground level, things are moving on apace with lots of rendering happening:



It's an odd sort of build this as the creative bit is sort of coming to an end before the main event actually starts, indeed we need everything finished off before starting the actual oven.

Another angle on the same scene:

Now the next bit I apologise for as I don't have photos, but it's an important step so I'm going to both bore you with words and nick some photos off the internet to show what I mean.

Ovens obviously get hot, and the idea is to heat up the bricks so that they cook the food rather than naked flames.

In order to make sure that they don't lose their heat into the concrete structure, the bricks need to sit on a layer of insulation.

There are several ways to do this. First up you can get sort of ceramic insulating sheets that can support the weight of the bricks and oven. I'm sure they may exist in Thailand, but good luck in finding them.

The other two options are mixing either perlite or vermiculite with cement to make a sort of lightweight and insulating concrete.

I'm no scientist so probably the easiest way to describe these two substances is that they are a bit like popcorn in that when heated they expand and become much bigger and fluffier than in their original state.

For those who understand the chemistry behind this stuff, from Wikipedia:

Perlite: Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an industrial mineral and a commercial product useful for its light weight after processing.



Vermiculite: Vermiculite is a hydrous phyllosilicate mineral. It undergoes significant expansion when heated. Exfoliation occurs when the mineral is heated sufficiently, and the effect is routinely produced in commercial furnaces. Vermiculite is formed by weathering or hydrothermal alteration of biotite or phlogopite.



OK, enough of the science bit, back to making our pizza oven.

Perlite is likely to be available in Thailand, but I couldn't find a supplier.

Vermiculite is however used extensively in hydroponics and as such is reasonably easy to find. I say reasonably easy to find, it still entailed a trip to Bangkok to collect some. I think we bought it from these guys, but I can't remember:

Bloggang.com : àËÅ×ͧ¨Ñ¹·ì :

Actually, looking at the website I'm not so sure it was as they also sell perlite, but anyway if you are after the stuff it may help a bit.

So, having been down to Bangkok to get seven large bags of vermiculite, I then needed to make the 'vermicrete' insulation layer.

It's quite a simple recipe, five parts vermiculite to one part Portland cement and one part water.

Mix it up, pour it to a thickness of 4 inches on top of the concrete slab and then leave it for a few days to harden.



I chose to do this myself because, as willing as my construction crew were to do things differently, being told by a farang that mixing something with the consistency of dry, flaky porridge would provide a suitable base for a heavy brick oven would I think be a step too far. They would want to chuck more cement in the mix, and probably a few stones for good measure.

A couple of things to bear in mind before you pour it:

1) Thoroughly wet the concrete slab before you pour the vermiculite as apparently it gets very crumbly if it dries out too quickly (and the dry concrete it's poured onto will soak up the water in the mix like a sponge)

2) Vermiculite is not cheap, from memory about Baht 1,000 per large bag (maybe 1.5 times the size of a normal bag of cement) so work out where you need the insulation remembering to take it beyond where the outer ring of bricks will go, and then do the rest of the stand in normal concrete. What we ended up with was something a bit like this:



(Both these pics are taken from the net)

Right, Chapter 2

Building the oven

Roobarb minimus can barely hide her excitement. The stack of firebricks are in the background together with one of the tubs of mortar:

First up is to lay the oven floor.

I did this myself rather than involve the crew as I wanted to take a bit of time to get it right.

The picture below is also taken from the internet but is pretty identical to what I did:



I tried to work out where the bricks would need to go to minimise the number of bricks I needed to cut, and also have the offcuts fill in the gaps so that not too much was wasted. I cut the bricks using a hand-held angle grinder with a diamond disc cutting blade.

One tip I discovered on the net was to use the dust that was generated by cutting the bricks to put under the floor so you can get it absolutely flat with no brick corners sticking out. This will be the cooking surface so keeping it as smooth as possible makes it an easier oven to use.

The floor itself was 42" diameter. Another tip was to then put a layer of corrugated cardboard around the outside of the cooking floor before doing a ring of vertical standing bricks. The purpose of the cardboard is to leave a small gap between the floor and the walls to allow the floor to expand at a different rate to the dome if needed. The cardboard will burn off in the first fire.

OK, back to the Thai photos...

The plan was for me to try and build this thing by myself, simply because I felt it was probably easier than trying to explain how to do it to my builder. Time however was running out as I had a job starting overseas, and Mr Chaang was keen to have a crack at it - or at least to be paid to have a crack at it.

So, about two hours in we'd got this far:



We angled the tops of the first, standing ring of bricks to allow the second ring to curve in at the correct sort of angle. It all sounds quite complicated but there is a simple solution:

Find the centre of the floor (which by happy coincidence was at a join between three bricks) and stick a small nail in there. Then cut a piece of wood 21" long. As you place each brick just rest it against the bit of wood. Keep doing this all the way to the top and you have a perfect 21" dome.

To get the initial angle correct on top of the first, standing ring then use the bit of wood to test it with one second ring brick on top, then when you get it right use that as the template for all the rest of the first ring.

Another brick in the wall:



The guy on the left is Mr Chaang, he was in charge of placement and mortar for the day. The guy on the right is his assistant whose job was to cut and shape the bricks.

The start of the inner arch:



So far its pretty simple. The angles between the dome and the arch become increasingly complicated the further up you go. I get the feeling the guy is beginning to work this out at around the time that the photo was taken.

getting the riser height all consistent with the different layers of finish is always a challenge. When I built my house it is the first thing the building inspector checked when he inspected the rough framing.

Looking great though!

Whilst the major engineering job was going on, the third, useful sort of cement-mixing fellow had been put to work sticking these sort of stone facing things onto the render:



I know they're not the real thing, but I reckoned that after a few years it'll probably look better than render would. Besides which, I had plans for the terrace floor and these would go with the look.

Another photo of the same sort of thing. There will be a sink on the left side, the hole in the middle is for the gas grill I have, and then the oven is to the right:



A picture of the sink:



The counter tops are just 60cm x 60 cm floor tiles. I looked all over the place for a proper under-counter sink and the only one I could find was in Global House, and it was some fancy German imported one for about 3,000 Baht. I bought a cheap Chinese stainless steel counter top one for a few hundred Baht and then bashed the lip a bit flatter before popping it in the hole and sticking the tile on top.

A bit of silicone sealant and we're good to go...

Originally Posted by danno5

getting the riser height all consistent with the different layers of finish is always a challenge. When I built my house it is the first thing the building inspector checked when he inspected the rough framing.

Looking great though!

Cheers Danno. It does take a bit of pre-thought which is not always a strong point amongst village builders. We had some steps made by a different crew elsewhere in the garden, they made exactly the same mistake too.

I guess it adds to the charm.