Staffordshire Build

[Thomobigands]

I appreciate that this is a backwards way of doing things but my oven is now finished. I put a few posts on here about various things along the way which other members have kindly helped me with but I neglected to keep an updated build thread. I did however take photos along the way so what follows is my post-build thread with details of how I chose to construct my oven. What I love about this forum and others like it is the help and support that people show towards each other, regardless of the type of build, materials, method of construction etc. What matters is simply that you have fun and enjoy building the oven, which you can then use to cook whatever you choose.

So here it is, my Pompeii, Staffordshire build 36 inch internal diameter oven.

The idea of an oven started a few years back. I cant even remember how the idea began but as soon as I downloaded the free Forno Bravo plans I was hooked! I remember looking through the photos and information thinking I don’t know how I am going to be able to do this or even what some of the materials were! But I, like others probably, broke the build down into stages and just focused/researched each bit at a time. With this in mind I set to work laying the foundation slab with the help of my cousin and his mixer as I had never even mixed concrete before!

The foundation slab was about 5/6 inches deep with a waterproof membrane and a sheet of rebar through the middle.

Next came the breeze block walls which were just sat on top of the foundation slab. Concrete poured down every other void with a couple more to boot. Once the concrete was in I would drop a length of rebar down the middle. The open entrance is supported by two lengths of angle iron that I bought as off cuts from a steel works in Tamworth. I added a central pillar to the build for added support.

[Thomobigands]

Once this was set, I cut hardibacker/cement boards across the top. Some wooden shuttering and more concrete with rebar.














I struggled a bit to understand the next bit but then realised I needed to try and keep the hot oven away from the standard concrete so as not to damage the concrete and also to retain the heat in the oven and stop it bleeding out. Originally I was going to vermicrete it but the long drying time and a few other things put me off. I opted instead for lightweight fly ash blocks that were about £1 each from a local builders merchant and I used maybe 15/20? I then surrounded them with more concrete and you can see this slab on top of the first slab in the photos.

[Thomobigands]

Once all this was set, I mapped out my oven floor that would sit over the sunken blocks. I only had a bolster and chisel and an angle grinder with a diamond blade that was a birthday present, so no fancy cuts here. The outer cooking floor bricks were just roughly cut as I knew they would eventually be buried and I sat the first soldier course on top of the cooking floor. Incidentally, the bricks are 42GD – 230 x 114 x 76mm. They were from kiln linings and I ordered 195 of them. I wasted quite a few messing up cuts and had about 40 intact bricks left that I sold on if that helps people with quantities? I used a hammer and bolster for 98% of the cuts and it was fine – I cut them on a flat, relatively hard area of lawn and just used the same spot every time. The few cuts that I had to do with the angle grinder I did with a respirator as well as goggles and just took my time. Having never used an angle grinder I was a bit nervous at first but it was fine. Sometimes I could not cut all the way through given the size of the blade so went as far as I could then gentle bolster and chiselled the rest.








I opted for homebrew to stick the bricks together. I think if you buy the tubs of readymade air set it can get quite expensive and plus that stuff is also no good for larger joints. I had to play around with the homebrew ratio because it kept cracking when drying. I cut down an old waterbottle and used that throughout. The ratio that worked the best seemed to be 1.5 scoops of red builders sand, half a scoop of cement, half a scoop of lime and about a quarter of a scoop of fire clay (also from kiln linings – I ordered 2 bags and used just over one bag although wasted quite a bit in the beginning through dodgy home brew mixes!). Once I knew my mix quantities I could then double up to produce a larger mix but never mixed more than that as I was quite slow having never brick laid before. I mixed in a flexitub. Dry ingredients first then water a bit at a time until a great scoop of the mix will stick to an upside down bricklayers trowel and show no signs of moving! Working in Insurance, I probably overdid it but when mixing I would always wear eye protection, a full respirator, rubber gloves and long trousers/sleeves. I am sure the neighbours thought I was experimenting with plutonium in the garage the way I looked! Once the mix was ready I would remove the goggles and mask to work.

[Thomobigands]

The layers built up quickly although I always forgot to stagger my joints as I went! I did the rear arch first with a couple of pieces of ply, with blocks sandwiched between. I read the tip about making the form smaller and propping it up which really helps when you are ready to drop it down. I left the form in place for a good week on each of the arches. Making the entrance with two arches allowed me to set the smaller rear one slightly smaller, which you will see provides a lip to then butt a door up to. You should be able to hopefully see on the front arch how I cut out the space for the flue.

I made my own indispensable tool which was useful. I only used it to gauge the angle though and never for the brick to fully rest on. Linking the dome to the arch is tricky but you have to just scratch your head around it. I ended up cutting a notch out of three bricks so that they sat on the smaller inner arch and I propped them up during drying. Not particularly pretty but it worked!

[Thomobigands]

For the final layers I put a sheet of ply inside the oven and screwed smaller ply offcuts around the edge from the top, blocking up smaller gaps with material. I then filled the top with sand and made a giant sandcastle dome to rest the final bricks on. It worked ok but I only used a bucket to prop the whole thing up with and it eventually collapsed – fortunately this was after everything had set or it may have been disastrous! Once all the bricks were in place I used smaller pieces to wedge into the gaps and then stuffed homebrew into all the gaps and over the top of the dome to (hopefully) hold it all together. This was left for about a week before taking the support out (and seeing that the bucket had collapsed!).










Given the arches were made of firebrick, I wondered if they would soak up rainwater so went with the addition of a second arch over the top in reclaimed brick. I also thought that it would make the front of the oven more of a feature.

The chimney. I took the advice from others and decided to make the chimney removable. It needs to be around a metre in height as I understand it to create the right ‘draw’ for the oven but then the oven is difficult to easily cover for the winter. I picked up a 1m 6inch diameter enamelled flue off ebay. At one end it had a slight ridge and so I cut around a 12 inch section off this end with an angle grinder fitted with a metal cutting disc. I then made little cuts all around the end so that I could bend these flanges out so that it sat on the front arch. I used a high heat sealant under the flanges and also smeared it all over the top and built up more brickwork around it. I filled the void between the flue and the bricks with vermicrete.






Here is a link to a separate post I did on the chimney:

ukwoodfiredovenforum.proboards.com/post/25328

I did a series of small curing fires at this point, before the insulation blanket and render were added, so that the moisture had an easier route away from the oven. Keeping the gazebo in place for these 'small' fires seemed like a reasonable idea to protect the vermicrete from the rain. However, as I stood and watched the fires, I glanced up to see a hole appearing in the plastic and had to frantically rip the whole thing down! My advice would be to therefore be careful with any structure over the oven when starting your curing fires!

[Thomobigands]

The dome was wrapped in Superwool Plus fibre – 25mm (couldn’t afford any thicker!). 4m at £54 delivered from Fireplug. Be careful what you buy here. As I understand it, some of the stuff for sale is the nasty stuff they are phasing out, whereas this is the same that Kiln linings sell and is the modern, safer equivalent. Not that it matters once its buried in the oven I guess but as a lay person, any way to avoid any nasty chemicals or materials is preferable.

Chicken wire over the dome then helps the vermicrete to stick. I allowed this to dry for a good week or so before covering the dome and the base with Tarmac one coat render (about 4 x 25kg bags in total). This dried for several days before I painted on two coats of Sandtex paint. Chalk Hill or something. It uses a lot and I was only left with about a third of the tin left.

Once the weather allows, the middle slab will be covered with broken tiles in a mosaic design. External adhesive and grout.

[Thomobigands]

Last couple of photos with the obligatory first pizza session and also some roast dishes. I am loving cooking on it and it has been well worth the time and effort in putting the thing together.















I hope this build thread proves interesting/useful to others and I wish you all the best of luck in whatever and however you build your oven.

[simonh]

Looks like great work, nicely done.

[wolvisfamily]

It looks great, and thanks for explaining the build so clearly. It's good to see how it came together. Now enjoy the food!

[Thomobigands]

Quick update. Managed to get the mosaics on tonight. They are just broken up surplus bathroom tiles but look ok I think. The adhesive and grout were from topps and are technically for swimming pool use so should be OK here! I'll grout it when I have some time and post a further photo.

[oblertone]

Mosaic looking great; from bitter experience I know how hard it is to achieve that look, well done.

[devontiger]

thom, great build, good job.

[Thomobigands]

Grouting done. It's completely finished at last! Only one pizza session so far but have done a full lamb roast dinner and lasagne tonight. I love it! I had lasagne, new potatoes, sausages, with garlic bread on a baking sheet over the lasagne. I can fit so much in, it's great!

[slen916]

really nice job on the oven and the food thom,plenty more pizzas to come i think..

[Thomobigands]

Awake early this morning so created and uploaded a you tube video build montage!

youtu.be/ZNnXdWeu3kA