Wood Fired Pizza Oven made over a gym ball

[@MarvelousLXVII]

I watched this video a year ago and finally made one. I went with perlite instead of vermiculite because I heard it holds up more. I did a ratio of 5/1/1 perlite/portland cement/water. I went through 4 cubic feet (sorry for america non metric we're idiots here) of perlite and about 1/2 a bag of cement. I did a layer of perlite cement, put a fire insulation blanket, chicken wire and another layer of perlite/cement. It is in the process of drying right now. I let the first layer dry for about a week. I will build it on a stand with wheels so I can move in the garage when not in use. Thanks for the inspiration.

[@sonofagun3193]

If you apply a clay liner inside the dome, you have better heat retention and a cooler shell. The clay liner will shrink when drying and a narrow cavity will occur between liner and insulating shell. After drying fire up. This will provide better Fuel economy, higher temperatures inside and better backing results. also increased longevity of the whole structure and no shell cracking. Remark: while drying the clay liner will crack a bit (this is normal due shrinkage and will not influence the integrity of the liner). Cracks can easely be repaired with clay slurry. After firing up, the clay liner is frost resistent. Alternativ for the vermaculite U can use perlite or expanded clay pellets or a mixture thereof. I made one of cheap expanded clay pellets ( the ones used in hydroponics) and cement and with a 1" clay liner and a steel door with adjustable air intake. I normally use olive fire wood which gives a delicious aroma to the pizza or sourdough bread. Cold or hot smoking of fish or meat is also possible and absolutely delicious. Regards from Spain

[@zennsx]

How does one apply a clay liner?

[@sonofagun3193]

@@zennsx Form Several equally thick pancakes of clay and stick it to the inside of the dome. Close the seams with your fingers untill the whole inner surface of the dome is covered. Let dry the clay untill hard. Than start at small fire in the dome to drive out the remaining moisture. Thereafter make a bigger fire inside the dome to bake the clay. Repair eventual cracks with clay slurry.

[@alanmccooker7829]

That's a great tip thanks. And olive tree wood is a great idea too!

[@tanwirkhan78611]

Can u do this on one go... i mean cover the ball with clay then cover with perlite. Or do u have clay first, wait for it to dry then perlite shell. Reading your write up I guess it can be done in a single go. Also it is weather proof. I.e left in the rain?

[@son-of-a-gun]

@@tanwirkhan78611 I have not tried to make the liner +shell in one go. I made the clay liner after the cement was cured and the low density concrete dome installed on it's final position. Once that was done I applied the clay liner. Doing so I could keep the weight of the dome relatively low for easy handling/lifting by one person (me). I guess technically you can make the liner + shell in one go but the total weight of the oven becomes a headache. After erection the outer surface must be sealed with lime or cement slurry to avoid rainwater entering the porous concrete dome. Regards from Bert in 🇪🇸

[@arabicgelato]

Nice job ☺ my compliments. Few questions to ask you, as I did 3 brick ovens and You know the work load time and cost. My intention to try a cast one in a new holiday house. 1. How much internal temperature you can reach ? 2. How long after using it holds hot its internal temperature ? 3. any cracks so far? 4. Do you know the external tempreture while it's working full please ? 5 do you still advice same ratio of mixture - cement or refractory please ? Thank you so much in advance..

[@MrSchnitzky]

Thanks for your inspiration. I've built an oven this way in spring this year and have used it a lot of time. A good thing was to put netting wire in the walls. What I had to change was the fundament. The sand was too hot and the bottom board begun to smoke a little bit. I used fermiculite instead of the sand and tiles as the bottom.

[@random-kc8gx]

Great video! Loved the creative use of the gym ball! For the inside of the oven if you could line it with an inch of fire clay mixed with fire brick aggregate it will last you a long time and resist cracking and heat loss.

[@elbishuki]

I've been watching a lot of videos lately to make my own oven and this is by far the most detailed, easy and best video so far. I'm will try this once I move to my recently bought house. thanks a lot..

[@cuthberm]

Hi, thanks for the comments, appreciated

[@wearedoomedunderbiden738]

I agree ...i can see myself Building that ..

[@graemethom7458]

Hi There. I'm in the process of building this at the moment! In hindsight are there any stages you would tweek or alter? Thanks 👍

[@libbyjensen1858]

NICE job! You did beautiful work!!

[@PVflying]

Hi, is the flue necessary? The delivita oven looks like the same shape, but without a flue, so I’m wondering if it could be omitted? Thanks for sharing your build video

[@cuthberm]

I guess not, the flue should, if it's working correctly, draw the smoke out of the dome, and therefore draw fresh air in through the front, feeding the fire. In practice I'm not sure if that really happens. The only other downside is any smoke without a chimney is coming back out straight into your face as you check your pizza.

[@PVflying]

Mr C TV thanks 👍 I’m gonna try one without a flue, but with a 50cm wide opening. Do you remember how many litres of vermiculite you used in your build?

[@RickyDove]

I've made one a bit like yours and fired it up today for the first time and I made 4 home made pizzas,, it did them in no time I was real impressed in how they work

[@JudiChristopher]

Ricky, did you do it exactly like he did it... or did you modify it any at all?

[@mitchdunn]

How is yours holding up?

[@son-of-a-gun]

Pizza's don't work bro!! You have to work making /baking the pizzas and the hardest work... To eat them all untill you burst. 👍😊 For an oven - (any oven) it's important to accumulate heat. A very low density concrete doesn't do that well. That's why it proposed the 1" clay liner which heats up independently. Clay is a very good heat accumulator. Without the clay liner your baking will will be less Regards from Bert in Spain... It's almost 40 degrees C here.. Pizza's bake exposed to sunlight... Good luck with your pizza oven project

[@billwill8067]

I am using perlite and refractory cement as the material, with chicken wire between 2 layers. I also am adding stainless still pins into the mix. Finally I am covering the inside with a final coat of refractory cement and the outside with perlite, refractory cement, and color. Do you think that should prevent it from cracking?

[@cuthberm]

Sounds a very robust mix your going with, time will tell, but that’s got to be a great start

[@billwill8067]

@@cuthberm This is incredibly frustrating. I am using perlite and refractory cement 5:1 mix. I cannot get the render to go up the side without falling back down. What I did get done seems to crumble. I covered it with a damp sheet so it would not dry too quickly, but even overnight it still does not harden, the render crumbles. What am I doing wrong?

[@mitchdunn]

@@billwill8067 Did you figure anything out Bill?

[@broesoo]

nice oven, i am also building mine. How many cm of sand have you put under the bricks? it doesn't hurt the wooden plank if I just put sand under the bricks. and how much height in cm have you put in sand?

[@frankhoffman3566]

I built mine 13 yrs ago, I think yours is a creative use of gym ball and materials, but I think you may need a refinement. The essence of a stone or clay oven is that the wood fire heats the surrounding rock, and the rock retains the heat, which cooks the bread (or crust).Vermicúlite, like perlite, is an insulator. This necessarily means that there will be little stored heat in the hardened mix. Your oven will heat fast, but I'm guessing it won't stay hot long. In mine I used a dense clay brick for the oven interiôr, and I put the perlite/cement mix over that. My intention was to keep the brick from sustaining heat loss from the outside. That way the heated brick retains the maximum heat and only loses heat through the oven interior. I think it might have been better to start with several inches thick of mortar, with a fire clay (refractôry)additive, and over that add several inches of your vermiculite mixture

[@marvincastro4206]

Im hoping you could help me

[@simonedmonds3359]

Firstly great video, but I have to agree with this comment re the top. Your oven will cook pizza ok, but when it comes to breads and roast, covering the ball first with a layer of something more dense like refractor cement, will make the oven more versatile. I used fire bricks, but then that is a whole lot more work.

[@frankhoffman3566]

@@marvincastro4206 ...If you have a question, I'll try to answer it

[@juliosalgado956]

@@frankhoffman3566 Hello Frank, i'm glad you are still with us. Can i ask something? I was told that white cement would be great for the interior alongside clay brics. What do you think about this? I intend to do one somewhat yours soon, any new knowledge to share?

[@frankhoffman3566]

@@juliosalgado956 ... Hello. Just to clarify, I don't do concrete as a profession. I have done quite a bit of research and have had successful concrete projects. My research indicates that white portland cement is the same as the usual gray stuff. It isn't better or more heat resistant. If you are talking about coating or painting the red brick with a white portland slurry, I wouldn't. You'd risk chips of the hardened cement flaking off and finding a way into your food. I'd want the interior surface to be a good, dense red clay brick, (except for the oven floor which should be fire brick)and the mortar joints regular bag mortar, fortified with about a shovelful of fire clay per 90 lb bag. A method I didn't use to form the oven, which I would have, had I known, is using damp sand to form the interior, then laying strips of plaster of paris soaked paper over that. After it hardens, the bricks are laid against it, conforming the oven to its shape. After everything is finished and hardened up, you dig out the sand. Really, the only issue is getting the right shape to begin with.

[@keithbrown4568]

Where did you buy your chimney and cowl. Ready to start building

[@halitderya]

Great job. It has enough space to cooking. Also portable. I will try. Thank you..

[@adirondackcarfoundry368]

Thanks for posting. Now I actually know how to construct one of these amazing little ovens. The gym ball idea is sheer brilliance.

[@billwill8067]

Did you have any issues with the sand not providing enough insulation for the wood? Would you have changed anything?

[@cuthberm]

some heat can be felt through the sand to the ply underneath, but at the end of the day I'm not running it for long enough for it to be a problem, there's only so many pizza's you can eat, then you have to stop or you'll be sick!

[@billwill8067]

@@cuthberm True. I think I will have some perlite left over, I may put a layer of the mix on the bottom then the sand.....

[@soobz]

Whilst the vermiculite is a good thermal insulator, it has no mass and thus will not hold any heat. The idea on a wood fired oven is the bricks get hot and radiate the heat once the fire dies down and can cook for many hours. I doubt the concrete will do the job anywhere near as well, though if just pizza is you sole aim it could be ok.

[@cuthberm]

Agreed, but I always get full before I worry about the oven cooling down too much, so it works for my needs, wouldn't work for a commercial applications for the reasons you've stated. Thanks

[@trevorcole460]

Fantastic video and workmanship 🍻

[@davidhallows2389]

Hiya, very nice job and video. Could you please tell me what type of cement you used for the fire brick base?

[@cuthberm]

Hi, firebricks were just laid loose on a pure sand base.

[@davidhallows2389]

@@cuthberm Thanks.

[@davidhallows2389]

Could you say how long the whole drying time took, after the 5 days? My mix is still really crumbly after 3 days, I'm panicking it's not going to cure properly!

[@alanbland5198]

Well done! I've just made a Tandoori oven out of terracotta pots and vermiculite. Bit of an effort sourcing a grate for the coals.... Now you've got me thinking to build something a bit like this could fit over the top of it...

[@mmtc311]

Love that you used a 10$ yoga ball for the mold! All the places selling 500$ molds just got played!!😂🤣😂

[@ferdinandofucci3975]

What kind of sand you put under the bricks for the base? What is it the recipe

[@cuthberm]

Sorry for a dull answer, but it was just builder sand, nothing special

[@Kamienios]

Hello from Poland. I plan to make one with this technique. i wonder what is sand for? Thanks in advance

[@duffgen62]

At 1.08 you show the CAD being slotted against the ball but then at 9.58 you seem to have another ( not concreted ) CAD. is this a 2nd dome or was there a problem with the 1st entrance. Also, can you tell me the material used to top the oven, is it a simple render that has been coloured ? Thank you.

[@hypota6872]

I saw a similar video about using cement and vermiculite and after some usage he got many cracks in the dome, what about you?

[@cuthberm]

The main crack was caused by the different expansion rates of the flue and the dome, no other cracks, i suspect the heat proof render does a very good job of holding it all together.

[@daveygivens735]

Hello, nice work. -All of these ovens I've seen have the chimney towards the front; apparently out of necessity (over the flame allows too much heat out). But I would prefer it towards the back. Have you seen any with a flue that transfers the heat to a chimney in the back? Is it necessary to have this simple short chimney in place at the front?

[@naths1229]

Nice work. I have a small doubt. The dome and the entrance are almost same height. I think the entrance should be around 60% of the dome height. Just my observation.

[@Moronicsmurf]

So great idea, easy way of improving the adherance to it use paper closest to the ball and make small "hooks" out of paper that the concrete mix can stick to. The paper will burn away at first burn, and the whole thing could be surfaced prepped from the inside once its cured out.

[@helshabini]

This is an awesome idea, after watching a lot of wood burning overs DIY, this is by far the simplest one. However I have some comments/questions that I'd love to share: 1- Wouldn't be cleaner to line the interior of the oven with slim fire bricks? I feel that the Vermiculite mix would have a lot of pores where ashes and dust can hide and would be very difficult to clean. 2- Why didn't you use more insulation with the sand? doesn't the bottom of the oven get hot? 3- Same thing regarding the fire bricks on the bottom, probably the heat will transfer onto the outer bricks and someone would get hurt touching very hot bricks that are outside the oven. 4- The opening for the over seems a little large, is there any scientific ratio that one should follow, or did you just go with intuition? 5- How much do you think this whole thing weights? I want to build one and put it in my balcony but I am worried about the weight. Thanks so much for the video, appreciate the effort.

[@cuthberm]

Hi, thanks for the comments. 1) I guess it would be cleaner, I sweep out the oven then use a small battery powered blower to force out the last of the ash and dust. 2) Yes the bottom of the oven get's hot, and you can feel the heat through the ply of the base, but it's not been an issue so far. 3) Not noticed the outer bricks getting hot, good point, need to check that, they will of course cool quicker being exposed to the air. 4) The opening is sized to take a standard pizza peel in width, that was my logic. 5) I can only just pick up one corner of it all assembled with the oven on top of the frame work, it weights hell of a lot, most of that weight is the sand and firebricks

[@helshabini]

+Mark Cuthbertson Thanks for the info. Much appreciated 😊

[@426superbee4]

The funny thing is? 🤣 He probably got the best pizza oven there is, just setting on his patio. A Weber kettle or a Smoker " Folks don't let the pizza oven bug bit ya." Look b4 you build or buy. Even your home oven will make excellent pizza ~ So lets watch him work his ass off on this thing 😆

[@williamrose9683]

Excellent job👍

[@cuthberm]

Cheers

[@ScottMProductions29]

Great vid. How is it holding up? Any cracks yet.

[@cuthberm]

Hi, crack around the chimney, due to different expansion rates of different materials, should have made the chimney out of the same material as the dome

[@elbishuki]

it would be nice to see a list of materials if it is possible

[@craiglaughlin6794]

Mark, Could you please tell me the outside dimensions of the finished oven? I'm trying to figure out how deep the outdoor counter top it will sit on needs to be. Thanks!

[@che-NY]

How much would you say that oven weightsWant to make a portable stand for the oven I want to make like yoursThanks

[@cuthberm]

The total structure is heavy, I can manage to pick one end up on my own, enough to wheel under a small trolley I made using flight case wheels (castors), I can then lift the other end up and put it all on the same trolley, it can then be moved around. I originally built the trolley for moving a piano.

[@cekfox2]

What is the red stuff that was put on last? And, you feel that this mixture of vermiculite and regular cement is heat resistant , so that it can tolerate temperatures of 600 F or more with the wood fire.. This type of oven then is light enough to put on a cart with wheels.. How much do you think it weighs approx.? thanks

[@cuthberm]

The red stuff is a heat proof render, expensive and it has cracked, so I don't think i would use it again. Including the wooden frame it would take 3 people to lift

[@sylviamolyneux-carr214]

Omg I'm doing this for my garden given me the inspiration 🙌. Going to get 75m ball. Wish me luck😊

[@illizizon9569]

Would it be possible to to plaster the inside with clay? I am asking because I have concerns because the cement could be unhealthy for cooking?

[@cuthberm]

It’s a good question and idea, I’m not sure how well the clay would cope with the heat, but it would give a much cleaner finish

[@illizizon9569]

@@cuthberm there are whole ovens build out of clay so i would think that heat is not the problem. but i think it could occur cracking because using different materials

[@simoncrombe7743]

Hi I am using this video to make my own pizza oven. I am at the dryingstage but am afraid the mixture is not strong enough. Could i be using too much water or to few(wrong) cement? I used fireproof cement. Greetings!

[@simoncrombe7743]

I used Refractory cement to mix with the vermiculite

[@bramhijman4829]

Hi! How long is it drying now ? And why do you think it's not strong ?

[@sultanasultan9605]

You are very geniuse, I have a question please,can i use the gym ball as a mold but I will be using the bricks building it intstead of the mixture of cement you did?

[@billwill8067]

Im going to try this, how did you know the size of the inner circle to cut out? I may use perlite instead of vermiculite. Is there anything else you would have changed after using your oven for a while now?

[@cuthberm]

I think I just made it 1 inch smaller in diameter than the ball, you can play with the pressure in the ball to make sure it’s a tight fit

[@orgohappy69]

I have saved the ceramic slabs/bricks from a very old storage heater. Do you reckon they will be good enough for the base of the oven?

[@cuthberm]

Would you be happy eating off them? It’s what the pizza sits on at the end of the day

[@orgohappy69]

I reckon so, I mean they clean and very smooth so can't see a problem. Im hoping because they are from a storage heater that they will hold their heat once up to temp.

[@son-of-a-gun]

Caution!! Old electrical storage heaters were often made with the use of asbestos insulation. Serious health hazard!

[@orgohappy69]

Can asbestos be in the form of stone slabs? I mean they are like very thick tiles. Thankyou for the warning though, I will have to do some digging.

[@son-of-a-gun]

@@orgohappy69 to get access to the firebricks inside old electrical heaters the thermal insulation must be removed. That's where asbestos was used in the old days. I do not encourage anybody to dismantle these old heaters to get hold of the firebricks inside.

[@guymace9796]

Hi quick question was there a reason you used the victus screed instead of the victus render? Interested to know cheers.. Guy

[@awoehler]

I’ve watched a lot of these videos and there are aspects to your build that I think are next level like: full shopping list at beginning; the form table is just high enough off the ground so the ground supports the fit ball; the base build is very solid but not intimidating to those with basic wood working skills, and the firebrick base looks a lot easier to do than some of the other over-crafted ones. I’d be interested to know how this oven is holding up and if there are tweaks you would make?

[@cuthberm]

Hi, thanks for the comments and feedback. It's now 3 years old, and the main casting has cracked around the metal chimney, somebody made a very good point on here about metal expanding etc. So next time I would change the sand in the base, to make that structure lighter, and therefore easier to move, secondly I will probably try making one from Perlite, and casting a chimney from the same material.

[@mitchdunn]

Did you make on? If so how did it go?

[@XFBO]

Greetings! Loved the build and has me wondering if I should give it a try! May I ask how it's holding up almost 4 yrs later?

[@cuthberm]

Hi, thanks, it has cracked around the flue, somebody in the comments section pointed out this might happen as the different materials would expand at different rates, which does appear to have resulted in the crack. Next time I’ll make it with a flue made of the same material as the main dome.

[@mitchdunn]

@@cuthberm Is the crack bad enough to make it unuseable?

[@cuthberm]

Mitch Dunn hi, isn’t big enough to affect it, just cosmetic really.

[@jdt8826]

Great oven. Can you tell me what the outside temperature of the oven is? Thank you

[@carmenzapulido9206]

Hi Mark we would like to know if we could use vermiculito 0-2 mm for building this oven. Here in Colombia is the one we can get.

[@pearljameric]

What would you recommend for someone wanting to build a larger oven? I was thinking about a 50" for commercial use. Would this design be able to handle that and could you think of something I could use to form the dome? Also does this retain the heat for very long? Thanks!

[@cuthberm]

wow, that's big, I'll have to have a think about that, I would be concerned that the mix would be strong enough over that diameter, and lifting, mounting the dome would be an issue? It doesn't retain heat for overly long, you have to keep feeding it with wood.

[@nickwood3634]

I don't know how expensive they are, but what about a "zorb" instead of a medicine ball?

[@jpmatarazzo5249]

Umm question, I noticed all the other videos are using Perlite, NOT Vermiculite, which makes sense to me because Perlite is used to aerate soil, and vermiculite is used as a moisture retainer. So shouldn't it stand to reason that vermiculite will hold too much water and explode if you heat it up?

[@cuthberm]

Hi, valid point, I was very careful to slowly dry out the dome, placing wet towels over it, I think I left it drying out slowly for about 4 days, I then only lit a small paper and kindling fire, before building up the heat on a separate burn later on. I chose vermiculite at the time as it was all I could find. I would try perlite next time for sure. Thanks

[@duffgen62]

How long did you leave it before removing the gym ball. I made my 2nd attempt 6 days ago and I would like to move it to it's final position. My dome is about twice as thick as yours so I'll need help.

[@dillansmit5418]

How much cement perlite did you need?

[@chrisarkell9095]

hi mark, how long did you cure the dome for? also, is the final coat that your put on watertight-can the oven be left in the garden without covering? many thanks

[@cuthberm]

Left the dome from Sunday night through to the following weekend, more for my available free time than anything else, I also placed damp towels over it for the first couple of days. I leave the whole thing covered up outside, as any rain water that would run off the dome, would then go on the bricks, then inside, then soak the sand, then rot the wood etc etc, just easier to cover it up.

[@jesteronetime]

Great job

[@cuthberm]

Thanks

[@hornybeast4340]

Hi, Sorry about the profile name. if i was to made the mood thicker to say 10cm would it still crack under the heat or is there other ways which can prevent these cracks.... Also the brown mixture you used to cover the over, what was that...?

[@cuthberm]

Hi, profile name is pretty funny! Brown mixture was the victas heat proof screed, to which I added a red cement die, the screed has now cracked in 2 places, after using the oven 4 times, for over 2 hrs each time, oddly the vermiculite mix hasn't cracked, which is obviously closer to the heat

[@philaphans2536]

Wow. The fact that the vermiculite mix hasn't cracked is key. That speaks to me more than anything. The rest is solvable using any number of means folks have brought up. Whether it's the foil or the blanket or a combination, it should prevent cracking of an exterior hard coat. I know you stated you didn't use refractory cement, but what are your thoughts on whether it would work or whether it might improve results. My main issue is mobility and not investing $3-5k in something that is permanent.

[@scottmcglynn5716]

Hi, great vid, sorry if this has been asked already but what do reckon the overall wall thickness is, concrete and render included? I'm in the process of making mine (85cm - gulp!) and I'm planning to put an insulating blanket layer between concrete and render.

[@cuthberm]

I'd say around 40mm for the vermiculite/cement mix, but much thicker round the neck and chimney area, for strength, and the render was 25mm? I'd go thicker if I was doing it again on the vermiculite/cement and maybe miss out the render, as it was very expensive.

[@scottmcglynn5716]

Many thanks - I've just added another layer to mine as there was no way it was 40mm. Just waiting for it to cure now.... Wish me luck!

[@scottmcglynn5716]

Well, it's done. And it's stayed up so far! Thanks for the video, great information and inspiration.

[@denkdiep]

I made a pizza oven using your technique, except that i made one extra simplifying chance that saved me a lot of time and money..... Instead of cutting out a hole in a board, i dug a hole in the ground and buried half the ball into the ground. Worked absolutely perfect....

[@cuthberm]

great idea

[@000jimbojones000]

Mark Cuthbertson i used a big Cardbox package and put the ball in there... Then formed the Dome and after it was dry i put it on my stand where i build the rest around it...

[@ljwarham6198]

Great build. Question, if I was to use refractory cement would I still need to mix in vermiculite?

[@cuthberm]

Yes as your structure would be far too heavy without I suspect

[@hogg8888]

so do the fire bricks just sit on sand ? very nice by the way !

[@cuthberm]

Thanks, yes the bricks just rest in the sand, and I then tighten up the sides of the frame to take up any slack.

[@hogg8888]

Thanks a lot . I think a lot of people have used your video as a guide. Nice one !

[@karlnoonan6166]

Hi what cement did you use thanks

[@leverwilliam]

I'm thinking of maybe setting a cement and vermiculite mix in a timber mould for the base rather than fire bricks. I'm guessing that would work with some support underneath to prevent breakage? could then smooth down the surface. Perhaps instead of putting sand and cement on the ply just pour in the vermiculite/cement mix, is this too heavy?

[@cuthberm]

Hi, I'm sure I've seen a video on youtube of someone making either a vermiculite or perlite base, it's shouldn't be too heavy, I've had criticism on here for my sand base, not being up to the job of stopping heat getting through to the wooden frame, but as yet it's not burst into flames!

[@leverwilliam]

Mark Cuthbertson thanks for your reply. I might give it a go, if it fails I've only spent a few quid making a slab! I'm attempting my version over the next couple of weeks

[@bernarddeham4787]

Thank you for sharing! What is best perlite or vermiculite?

[@reheat007]

Great job....amazing. So simple Just a comment on the outer rendering cracks. It's most likely caused by the expansion differential between the two different substrates. You said the outer render gets fairly hot so there's a heat transfer through the Vermiculite which will expand at a greater rate than the rendering thus causing cracks. A layer of aluminium foil held in place over the Vermiculite then the render applied over this would alow movement between the substrates thus reducing any likelihood of cracking. Just my tuppence worth.

[@cuthberm]

Hi John, thanks for the comments and thoughts, possible the most sensible suggestion and explanation anybody has made so far. I'm thinking of making another with Perlite, so I will try and incorporate that idea.

[@wlehtola]

I was scrolling to see if I was the only one who wondered how two so dissimilar materials would react and how much cracking would occur as a result.

[@richardpeterfox1]

Afternoon. I've had a go at making this this weekend. However the following day the vermiculite mix is flaking off in places. Any suggestions to fix it? Up the concrete to micafil ratio?

[@simoncrombe7743]

Mine is doing the same!

[@mitchdunn]

How did yours hold up?

[@nolbex]

did you use chamotte mortar or glue to combine bricks on the base ?

[@shyamtank2767]

hey needed a help. I bought vermiculite, but it is in partial powder form. not as shown in the video. will it work effectively?

[@cuthberm]

I'd be worried you'll get a very dense build and the dome will be heavy

[@dosvidos569]

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[@diegroblers]

Fantastic work, thanks Mark. I'm not looking to build a Pizza oven, but I am looking to build a wood-burning fire bowl, and I would definitely use some of your methods. Two tips, if I may? Spraying the ball with cooking spray or using anything similar (including Vaseline) on the ball will keep the cling film from moving around when you're applying it - it's a cooking trick. Second, if the gym ball is expendable, as tip to skip having to build the frame for the ball you could mix polystyrene beads (bean bag filler) with PVA glue, cut a x into the ball, and half fill it with the mixture. Then duct tape the x closed and blow up like normal and leave to dry - cut the ball off and you have a form to use for the oven. Edit: A question if you don't mind - can the base be built using cement and vermiculite also instead of fire brick?

[@piotrksaata5202]

hi. how is your oven doing? any cracks. what would you do different if had to build another one? thanks

[@cuthberm]

Hi, I would move the chimney further back next time. The main structure hasn't cracked but the outer render has cracked, so I would look at doing something different with that, somebody on here has suggested a layer of foil between the vermiculite mix and the render.

[@piotrksaata5202]

that is awesome. chimney closer to 5he dome or put it in the back of the oven? I will be starting to build mine this weekend. I have insulation blanket that I am planning to put over vermiculite and the cover it with concrete shell.

[@Stratoszero]

Brilliant video, nice and simple, not like others introducing brickwork etc (theres an Aussie guy does a nice one too). One question, how has yours been for cracking and overall weather proofing since? Theres a lot of vids use chickenwire, fabric insulation and all sorts as well?

[@spiritwings4592]

That Aussie guy that your speaking of made the very first one. Every body else followed him.

[@clark17forever1]

hi Mark quick question i just went to my local garden store for vermiculite but it seems as if it is small pieces of styrofoam. if wasnt rock like. that is my question i guess what im asking is it a crushed rock?

[@marcodasilva1403]

Is it okay to use the cement/perlite mix to make the base instead of bricks? I want it to be somewhat portable.

[@cuthberm]

Hi, the key to this is the bricks absorb the heat from the fire, and ultimately give back to the pizza and cook it, a cement / perlite base would be a good insulator, but not good for cooking on

[@paulsheppard9171]

4 years on, is the oven still ok , no cracks?

[@ozgurkalay8069]

im planing on using 3ver to 1 cement do u think this would be stronger or more prone to cracks when hot? im using fire cement. thanks.

[@Dairyteats]

Just saw your video. How did the oven hold up? are you still using it? Thanks

[@cuthberm]

Hi, lasted a couple of years, but the winter weather took it out in the end. Thanks

[@gregoriocassandro]

how much does it weigh, without a base? Grazie!

[@cuthberm]

gregoriocassandro, hard to say, maybe 40kg?

[@richgiles-grant4456]

Your oven is amazing am just about to order the materials to construct mine. Where did you get the fire bricks from and also how thick is the vermiculite dome?

[@cuthberm]

+Rich Giles-Grant Hi, thanks, I was very fortunate in having a friend who sourced the fire bricks for me, they are available on line, www.victas.com, but the postage is the issue due to the weight, better to source them locally if you can. The dome is approx 5cm thick, much more between the dome and tunnel section and around the flue, as I thought this might be a weak point when lifting and moving etc.

[@lou4053]

Hello, please Can you tell me if it still good? Do you have New suggestions ? Thanks you.

[@NaughtyGoatFarm]

How much perlite and cement do you think this would take to build?

[@BeeTee69]

This looks perfect! im thinking of making one with a clay inner layer and then an insulating material over it. Putting it directly on fire brick would be perfect. Would these combinations pose troubles with having different expasion rates?

[@terrorista87]

Che diametro hai usato sulla base del legno? Cemento refrattario?

[@cuthberm]

Hi, no just normal cement, the diameter of the hole was about 1 inch smaller than the diameter of the ball.

[@Dan-ji4db]

what kind of sand did you use under the brick? i have a bag of paver sand i didnt use on another project that i could use here...

[@cuthberm]

Dan H it was just a bag of sand I had around as well, paving sand should be fine, thanks

[@ricky89ization]

Hi mark I made this the other week but I didn't do the doorway thick enough how can I rectify this???

[@chasebunger1811]

I was thinking about doing something very similar to this, although I was going to use a homebrew refractory concrete mix that I found on fornobravo....any ideas how much this would weigh approximately? I love the idea of building a stand out of wood rather than having to use concrete blocks and pouring a special foundation just for this.

[@juancubaabisrror3636]

Hello which with the amounts of material you used or the proportions

[@trotter5099]

Hi Mark, sorry if this is a repeat question, but would there be any advantage of using fire cement instead of normal cement, Thanks in advance.

[@cuthberm]

Hi, I don't honestly know, it can only help I guess

[@trotter5099]

Ok, thanks but will probally stick to normal cement as you have.

[@ericstocks9296]

Yes there are . I fire cement is designed to withstand high temperatures whereas a normal cement is not and will crack and disintergrate over time whereas a refractory product will withstand the extremes of temperature without cracking

[@trotter5099]

But is that Fire Cement safe for Cooking in ?

[@ericstocks9296]

yes although Firebricks 230 x 114 x 25mm would be better Firebricks and fire cement get hot and retain the heat and so will cook the base of the pizza beautifully giving you a nice crispy base

[@Muzaffer33_33]

Easy and very good job and idea man.

[@billwill8067]

Im patterning my table like yours. My oven came out to what I think is 200 pounds!... With all the brick on the table top it will be 400 or 500 pounds. Do you think your table design will support that weight?

[@cuthberm]

sounds heavy for the oven, I could easily pick up the oven myself on my build, it felt relatively light, the weight for me was in the bricks and sand.

[@ricky89ization]

Hi mark, do you have a list of the items you used??

[@ricky89ization]

Hi mark, how much vermiculite/concrete did you end up using? And roughly what you estimate the cost to be to build one? Thanks.

[@cuthberm]

HI Ricky, about 3/4 of a 100ltr bag of vermiculite and half a bag of standard cement. Fire bricks are the big expense, I managed to get them through a friend, you need to find a local supplier or the delivery charge will really hurt. I'll reply to your other question with a list and costs once I've dug them back out.

[@nicksnicknet]

Awesome video, and thanks for replying to all the comments because it really helps others out there. I've ordered an 85cm ball - do you think the dome would be too big, and would I need much more Vermiculite than a 100L bag? Did you have much left over?

[@cuthberm]

Thanks, I had a little over, maybe a quarter, I'd go for 2 bags, as you will want additional thickness over mine for strength, as thats a mighty ball your covering

[@mitchdunn]

Did you make one?

[@AndrewOvenden]

So, here's a question for you: when you built your base, the bricks extend all the way out to the edge of the countertop/tabletop, well beyond the side of the oven. I'm currently right at that stage of building my oven. One would think that the bricks extendig out that far would "suck" or pull the heat away from the oven. Do you think that's the case? Would I be better off cutting my bricks to fit the outside edge of the oven? Your design is easier than my alternative solution, I will admit.

[@cuthberm]

Andrew Ovenden I see the point you are making, as some bricks will be both inside and outside the oven, and yes maybe draw heat outside. But the extra work to trim the bricks seems really large vs the benefit?

[@AndrewOvenden]

Yeah. Sadly true. Still, I'm hoping to find a friend with a tile saw. ... or see how many more household projects that I can find that would justify renting a tile saw. Your video is great by the way. I've been going back and forth between your video and JJGrice's video to design and build mine.

[@tonygiordano1813]

Salve la misura della dima della bocca delle entrata delle pizze che misure a? Grazie in anticipo

[@cuthberm]

the width of the entrance is approx 15 inches

[@Robswoodworkingdiy]

Great video. Have to ask how much did it cost to build. Assume you'd in the UK.

[@cuthberm]

Hi, yes in the UK, biggest cost would have been the firebricks, but I was given those by a friend, other materials probably came to £350 I’d guess, you can see most of the pricing at the start of the video, plus the render and the wood mounts up in price before you know where you are!

[@oipmic5769]

grazie mille .mi scusi un altra domanda alla fine va ricoperto con cemento refrattato ? ho cosa è la sostAnza rossa che sai alla fine

[@cuthberm]

It is a pre mixed heat proof screed that I bought online, google heat proof screed victas.......good luck

[@RickyDove]

What great idea you have inspired me to build one for myself ,, I've started it, just waiting for it to dry now

[@mitchdunn]

How did it turn out?

[@jamesoates6309]

How long did the oven take to dry before you could use it? Also did you have to leave it covered with wet cloth to prevent cracking? Cheers

[@brettmattinson7262]

Hey how did the oven hold up over the past 6 years

[@eduardosanchez-dv7fz]

hello, just get thin perlite and vermiculite. will serve? Greetings.

[@MM-jx9si]

Thanks for the video. Quick question: What would be the very best materials one could use to make this structure?

[@eddieclayton1022]

Where did you get the Vermiculite

[@cuthberm]

Hi, from eBay, thanks

[@nicklassjoqvist377]

I see that you used 5-12 mm vermiculite, i cant find and order in or to sweden that size, but i have 2-4 mm, you think it will work??

[@mormorMaya]

Har du byggt någon ugn ännu ? Hur har det gått isf? Jag har köpt vermikulite i den storleken.