23 May 2013
CLAY OVEN BUILDING YOUR WOOD FIRED PIZZA OVEN
ALL THE STAGES TO BUILDING YOUR OWN WOOD FIRED PIZZA OVEN
1. The base
2. Laying the brick oven floor
3. Making the sand dome former & first clay oven layer
4. Cutting the oven door entrance
5. Removing the sand former and lighting the first fire to dry out the oven layer
6. Building the brick arch and clay chimney
7. Building outer decorative brick arch (optional)
8. Insulation clay slip layer
9. Final clay oven layer
This is hopefully a nice and easy stage by stage guide to building your own wood fired clay oven, I will included all the pitfalls and helpful hints that I find along the way along with some of the scary moments I am sure to have!
Here it all starts, the first stages of construction to what I hope will be a fabulous home made clay pizza oven, which will give me many hours of wood fired cooking and lots of thin crispy pizzas for all my friends and family... Well that is the theory, and I will blog my building experience which all being well with the weather should take me on/off three weeks.
Lots of google homework and finding a fantastic blog (clayoven.wordpress.com) was the biggest help, this guy has taken the river cottage clay oven building course and then blogged his own build, which I thank him for soooo much, as he is a fantastic writer and has documented very easy to follow step by step instructions with photos that have given me the confidence to attempt the same build, with a couple of Kristi tweaks!
The fabulous bonus, apart from making this myself is the low cost which I almost missed because I was going to buy a pre-fired made oven at approx £1500, (two years birthday presents and my 40th) but when I rattled off all my questions to the company confirming that their oven is ready to go once delivered as they stated it turned out it would be advisable to insulate the pre made oven, this entailed £500 more and a lot of chicken wire and plaster.
This is when I decided I can make my own oven and is it really that awful if it is a bit rustic and homemade, my answer was NO, now all supplies are in at a cost of £380, which would be £150 lower if I could have found re-claimed fire bricks, but alas 3 reclamation yards, second hand shops and ad-papers and no luck meant I had to order new ones from Vitcas.
I have made a 1m, circle cooking base with a 130cm (ish) finished clay outer from 3 layers
For the clay Oven
18 x 25kg of Tandoori ceramic oven clay (No need for puddling) Wahoo!
1msq base= 51 fire clay oven bricks
18 bags of sharp sand
1/2 bale of shavings
15 re-claimed red London fired bricks for entrance arch
20 re-claimed red London fired bricks for outer decorative arch optional
For the Base
patio slate tiles
Wooden railway sleeps
DO YOU NEED FOUNDATIONS?
I put my base on my patio and did not have to dig any foundations.
1. THE BASE/PLINTH AND FIRE BRICK OVEN FLOOR
I choose to have builders make my base with the breeze blocks for me so that it was ornate and had a functional log storage space, my base cost me £500, to save on costs choose the railway sleeper base and look at clayoven.word press.com as this blog will give you all the instructions for the base.
MY PERFECTIONIST SIDE IS SO GRATEFUL FOR MARKING THESE MEASUREMENTS BECAUSE I COULD RELAX FOR THE BUILD AS EVERYTHING IS IN PERMANENT MARKER AND I WILL NOT HAVE TO STRESS ABOUT MEASUREMENTS FOR THE REST OF THE BUILD I HAVE GUIDE LINES...!
Mark out on the top of your base a 1msq, this is for the fire brick oven floor. Then you will need to mark the centre of each meter line, this is so you can find the centre of the meter square. Then drawing a line from each centre marker side to side and top to bottom, will give you a marker in the middle of the square. Take a pencil and tie a length of string around it, now place the pencil on one of the four centre markers, have someone hold down the string taunt and tightly on the centre marker of your base. Draw a circle, this will be the line you follow with your sand former dome, and will be the inside cooking base of your wood fired pizza oven.
Now to mark out the finished clay brick oven size guide lines, for this I allowed seven centimetres for each clay layer, three in total, therefore the 21cm total depth, ish. For this measurement I just measured 21cm from the edge of the centre of the meter square again and drew the outer circle so that I now know the min and max measurements.
2. LAYING THE OVEN FIRE BRICK FLOOR
Old red London fired red clay bricks v re factory fire bricks.
There is little between them, however re factory bricks are the best heat conductors and heat quicker and stay hotter for longer, however if you can not find fire bricks it is still ok to use solid red clay old London bricks, these do the same job, but are slower to heat up and can sometimes flake a little. but if this is all you can get this should not stop you from using them. I have decided that I would like to keep my oven long term so I decided to use fire bricks, which meant ordering them direct which has cost over double more than using the red clay old London brick the reclamation yard had, but for me this is about the finished food and I want to start with the very best to end with the very best.
Lay a layer of sharp sand over your 1 m squared marked out base approx. 1 inch deep, I did use a spirit level to roughly check it was level, then I started to place the bricks in a herringbone pattern as this will help hold the bricks in place, I used a rubber mallet to gently tap the layered bricks to level them so that I had a smooth level surface. I have extended the fire bricks out to the edge of where I assume my brick arch will be and this is as far as I have got today. I cant wait for tomorrow to finish off some of the brick edges for cosmetic reasons and start the sand dome construction. I am hoping that the big stage of sand dome, first clay bricks and arch construction will go smooth and then it will be home sailing after that... Look forward to telling you how it goes...
3. MAKING THE SAND DOME FORMER
& FIRST OVEN CLAY LAYER
This was very easy to make, but if I had to make a really round dome I would have struggled a little, I think, I found it easier to re-mark the centre points of the 1m2 outline and then to draw side to side to make a cross in the centre of the square, I then took my pencil on string, place my pencil on the centre point of one of the edges and pinned the string down on the centre point and drew myself a new circle which made the outline for the clay dome to follow.
I emptied 16 bags of builders sharp sand onto the centre of the oven base and started to form the dome, I found having the line to adhere to kept my dome in a almost perfect circle, my reason for this it that the outside of the dome will form the inside of my oven but also start the outside shape of the oven too. Just keep adding sand to the top of the dome until you have a lovely shape. I did find it very helpful to have my husbands eye from another point of view and standing on a chair really helped looking at the dome from above to help keep it equal all round.
I decided to make my dome 60cm tall which is half the height of the 1m2 base.
Next job is to cover your sand dome with wet newspaper this was a little more of a challenge than I anticipated! I eventually found it easier to enlist my husbands help and as I soaked each sheet of a newspaper in water my hubby laid each sheet on the sand dome, starting at the top and then using the stick ability of the wet paper on wet paper, laying each sheet from this top central sheet sticking it to the next sheet and working your way down and around covering all of the dome.
Now I am done until tomorrow when I will start the clay brick covering, I am on a schedule due to the lack of sunshine we are having this year! Therefore I am now an avid weather watcher and know I have four days of sunshine to get the first four stages complete before the rain sets in again.
MAKING CLAY BRICKS & COVERING THE DOME
Because I have brought pre-puddled clay in 25kg sacks it was easy to cut the bricks from the block, I cut the block in 7cm panels and then each panel in half to try and keep a uniformed thickness. I got 6 bricks per 25kg sack plus a sliver left over, which you will find useful for filling gaps as you go.
Top tip is to start this stage by mid morning, the reason for this is that this stage will take you approx. 4hrs if you are doing it alone, and then you will want to allow another 4hrs of drying time for the dome before you mark out and cut out your door, you really should cut your door the same day as laying the clay bricks, because the clay is firm but still soft and if you leave it to the next day you risk crumbling or cracking when you try to cut the door space.
As this is going to be the first layer and the actual inside of my clay oven I smoothed the inside of the brick with a little water and my hand to a reasonably smooth finish. Take your first brick and press it against the base of the dome and compress it into place, I did push quite firmly, using your hand in a "kung foo chop" style movement hit the top of the brick towards the oven, this sort of creates a wedge shape on the top of the brick and helps push it firmly to the dome.
The reason for the "kung foo chop" is two fold, firstly to ensure you press out any air from the clay and to make a neat tight fitting brick against the dome and secondly it will help when adding the next layer of bricks on top. Add your second base brick and mould it onto the first brick, continue this all the way round and then you will have formed the first layer of bricks, repeat round and round and up and up all the way up until you have covered the dome completely.
The first layer is complete! Now I have to leave this to dry for 4hrs before I can cut the hole for the oven entrance. For the size of the door, which is really important I trolled through forums and google's many information sites and the one formula that seemed to pop up over and over from seasoned oven builders and looked similar to the size on most of the pictures on google images confirmed that the height of your door should be 63% of the height of your oven.
4. HOW TO CUT & CALCULATE THE MEASUREMENT OF YOUR OVEN DOOR
My oven is 60cm tall therefore 63% would measure my oven door at 38cm high. Then the width, I went with the most popular measurements of half the width of your oven, now my oven is on a 1m2 but only four points touch the meter line, therefore some old school mathematics equations worked out that my oven was really 82cm therefore half would be 41cm.
I also measured all my favourite roasting tins and all came in under 40cm and then the pizza peel I brought is 12" so everything should fit just fine. I was worried about the height of my beer can butt chicken but this height is fine.
The extra information I have learned is the shorter the height of your door can mean the smoke will not want to leave the oven, and if you cut the door too tall your fire will burn quicker which will contribute to heat loss and your oven not come or stay up to temperature.
To cut my oven door I made a paper template of my measurements and marked it on the clay with a pencil and then cut the shape out. I then smoothed the shape of the arch and will deal with the removal of the sand and fire of the oven tomorrow.
Well the next stage is to remove the sand and light a small pencil kindling fire to help dry out the clay, then to repair any cracks, eeek apparently don't panic there will be some! Then to build the arch and chimney, after that I plan on taking a week off as my hands are very sore and a bit bruised from bashing all the bricks but I am sooooo pleased with my progress and can't wait to cook !!!
This brick will be on the inside of my oven dome, a nice family motto, and my son Oscar has also put his hand print in the base when the builders made if for us last year.
5. REMOVING THE SAND AND FIRING THE OVEN
This I think so far is my most terrifying moment, I did not want to remove the sand in case the still wet clay dome collapsed but it had to be done...
Here it goes, I actually put this bit off for 24hrs as I was scared of the dome collapsing, I started digging the sand out by hand slowly and by the time I had removed one third I started to feel more confident and as the roof started to be exposed and not cave in I felt even more confident that the dome was going to hold its own. 18 sacks of builder sand later and the oven is ready for the first firing to help dry it out. I have read that you may get some hissing and steaming and few cracks but not to worry you can fill the cracks before the next stage...
So here it goes, lighting the very 1st fire in the 1st clay layer...
This stage is two fold, firstly and foremost is to help dry out the oven and not too fast either, but most importantly it is to confirm the size of your oven door. This is to help you confirm or adjust the oven door because of how the smoke behaves. Because the oven floor and dome is damp your first fire will smoke a lot which will give you a good guide line on where that smoke wants to go.
If your oven door is too low then the smoke will pool up in the top of the oven dome which is not good, and if your oven door is to high then all the smoke will leave, this is a hard guess as you will want all your smoke to leave, my guess is I want to see the smoke pool for a second and then leave without any effort, this means the oven door is the right height.
In the event of oven doors stress I believe a slightly larger door is better than a smaller one, this is because it may make the wood burn faster and cost a little more in wood but there will be efficiency and no smoke pooling. But I am very happy that the calculations I followed are working perfectly.
Fingers crossed that this is confirmation of a successful chimney and that my calculations based on the most common found on the Internet, forums and books is correct, (63% height of the dome and half the width) and so far I do believe it is so, all the smoke pooled and came straight out the oven door therefore I feel no adjustments needed
The oven drying out nicely you can see the colour change then you can see some cracks forming, I am really stressing over these cracks, the blog I am following says DON'T PANIC it is ok, just fill them once the dome is cold and then move on to the next stage, but I am really stressing !!! There was some serious popping, cracking sounds and hissing but I am trying to chillax about this...
Finally the oven is up to 500 degrees temperature WAHOO this is so hot and the dome has held itself together, a few cracks that I think are frightening but they seem repairable. So now on to the next stage of insulation coverage.
6. BUILDING THE BRICK INNER ARCH AND CHIMNEY
I first made a sand dome former following the line of the oven door. To fix the old reclaimed London clay bricks I used clay as opposed to mortar, the main reason for this is that mortar would probably crack and flake over time from the heat of the oven. I am glad that I am keeping my oven rustic as this allowed the freedom to have a slightly wonky arch!
Very proud of my slightly wonky leaning pizza tower homemade arch!
The start of building the chimney, this again I did lots of comparing on the internet as I did not feel comfortable drilling out a whole in the oven top once it was hard, as the guide I am following does, in hindsight maybe I should have cut the chimney hole when I cut the door? I found equal information for building the chimney above the door and for cutting a whole in the top of your oven. The picture below is the design I followed as I already felt super confident that my oven door was the correct size because the smoke from the first fire came straight out of the door and did not pool, so it seemed reasonable to assume that my chimney would work efficient if above the front door.
This I will know for sure when I fire up the finished oven !!!
Whoooo my finished chimney, I assumed it would take me approx 1hr to build the chimney, it took 3hrs, so my husband had to hold a torch for me to finish off the inside of the arch because I didn't start till late and it got dark! I am really pleased the sides of the chimney are re-enforcing and supporting the arch as it was leaning back a bit from my wonky building. The oven entrance is now protected as well from knocks and the inner brick arch adds a bucket full of character.
Side view of the finished chimney, once the other two clay layers have been added to the oven you will only see the top 6" of the chimney.
7. BUILDING THE DECORATIVE OUTER BRICK ARCH
First I made another sand dome former to support the brick arch and then using mortar this time not clay I started to build the arch, I did not measure or work out the mortar gap as I am being rustic, but my arch is a bit wonky, I know why, I can see I laid the fifth brick with a hint too much mortar on the right side and it lowered my arch on that side but I am ok with it, and I am not doing it again
Ta Daa... The brick arch
I forgot that my first brick arch was leaning back a fair bit, and of course I had to follow the curve for this arch so after 6 bricks each side I realised that this arch was leaning back too, so I started to try and place the rest of the bricks slightly forward to bring this arch a little more upright, but it matters not as this is my rustic built pizza oven with love...
I felt a little worried removing the sand but the arch is holding it's own thank goodness. I am really please with the double arch as it makes the oven feel bigger and a lot deeper now, even though it is not and I also love that I now have a warming area because of the outer arch which gives you a little more control when your are cooking.
8. MAKING THE CLAY SLIP INSULATION LAYER
I used 4 x 25kg bags of clay and added approx 30% of that volume in water, you can always add more water if your clay slip is to thick. You want the slip to be the consistency of yogurt. One of the best tips I was given was to soak the clay in the water for a couple of days before your going to use it, this made mixing the clay super easy, the other tip was to beg, borrow or buy a mixer attachment for your drill and this was a well worth purchase and made light work of mixing the slip to a nice even consistency.
Transferring the clay slip to the wheelbarrow so that mixing in the shavings will be easier.
Next is to add the shavings to the clay slip to create the insulation layer, in all I used just over a third of a bale of shavings. I just kept adding shavings into the clay slip in the wheelbarrow until I had a firm consistency that held together if I dropped it from waist height. Excuse the gloves lol, I burnt my hands with the cement making the outer arch and I found it a challenge having to wear these gloves as I generally love to be a hands on girl.
As I did for the first clay layer, I formed bricks and laid them against the clay dome, pressing each one down firm to ensure no air gaps and moulding each brick into the next, this stage took me in total 3hrs to do, hopefully with enough sun this layer should be dry in four days and then I can move on to the very last stage...
Insulation clay slip layer complete.
9. FINAL CLAY LAYER
Laying the final clay bricks, this stage is exactly the same as the first stage, only 40% ish more clay will be needed as your dome is much bigger than when you started. Once you have finished laying all the bricks sit back enjoy a well deserved cold beer and marvel at your well built oven, and if you are like me, start to get excited about all the cooking you are going to get to do...
My finished clay oven, in all it has taken me approx 40hrs over 3 weeks and lucky for me we had some great sunshine which helped my oven dry out.