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Picture of Vermiculite, Gym Ball Dome, Wood Fired Pizza Oven

I built this pizza oven for my family instead of buying a similar one for at least £700 ($900). The ones you can buy still require a base to be made or bought and you have to assemble the oven as well. I was able to create something unique and bespoke to fit the small space that I had available.

I hope that you decide to make one for yourself. You will enjoy cooking (and eating) tasty stone baked pizzas that cook in seconds as much as you will enjoy the satisfaction of having made the oven yourself from scratch.

I spent under £320 in total on materials. The only parts I already had available for free were the 14 house bricks and scrap wood to make the jigs and some hardcore for the base.

I hope you enjoy making your own wood fired pizza oven! Go create!

Step 1: The Base / Foundation

Picture of The Base / Foundation
IMG_20180623_144256.jpg

For an oven this size, clear an area larger than your intended base. For my base of 0.9m, I cleared an area of 1.2m square.

I used concrete paving slabs for the base instead of pouring a slab of concrete. They are very thick, strong, solid slabs - perfect for the base.

First, compact the ground beneath where you want to build your oven then add approximately a 15cm layer of hardcore material to build up a solid sub surface. The gaps between the hardcore should then be filled in with a few bags of 'scalpings'. Then go ahead and compact everything down as solidly as possible with a hand compactor or something similar and heavy.

Using string and pegs, mark out a square area equal to the final size of your four slabs and then fully bed the slabs in with a 3:1 mortar mix - 3 parts sharp sand, 1 part Portland cement to a thickness of about 15cm. Don't be tempted to economise on materials by 'dot and dabbing' as you will create a weak base with air pockets. Use a spirit level often to make sure the base is nice and level as you go.

lkjfdsa15 days ago
Vermiculite contains asbestos mineral, you should buy a filtered mask for working with it.
leopham lkjfdsa15 days ago
I personally extremely doubt it... This is likely related to a report about a mineral mine that was closed in the 1990's. Some houses built in the US during that era were insulated with this specific vermiculite from that specific mine. Since then the mining of vermiculite is thoroughly regulated. Vermiculite for gardening will be safe but if in doubt, wear a mask, vermiculite is quite dusty anyway so just wear a mask would be my advice.

Remember that anything you read on the internet may or may not be correct - Including my own advise above. Just wear a mask if you’re worried about it.
The Montana mine you mention produced 70% of the US supply and 80% of the worlds supply of Vermiculite at peak production and it is estimated that 35 million US homes contain asbestos contaminated vermiculite insulation. This is not a small problem being blown out of proportion by an internet rumor. There are justifiable reasons to be concerned where blown in insulation has been installed.

The US EPA conducted testing of consumer gardening materials containing vermiculite in the early 2000’s, four years after the Montana mine was closed. It still found asbestos in vermiculite sourced from other mines although only a small percentage contained asbestos and and even smaller ( 2-3 products out of 35 tested) contained high enough levels to be a concern. The point here is that asbestos contamination is possible where ever vermiculite is mined because the two minerals are formed via similar geological processes. Not every load of ore is thoroughly tested and therefore not every product can be quaranteed to be free of asbestos. Just like how not every sheet of gypsum board can be guaranteed to not contain heavy metals

This being said, your advice as well as the op’s regarding wearing a mask is justifiable. Whenever handling dust producing material, a cheap respirator, properly filtered and fitted for the application is always a safe bet. You can’t nor shouldn’t trust that someone else, government agency or corporate interest is looking out for your best interest.
Mimikry18 days ago
now I start dreaming again.....
but I'm afraid the winter in northern Sweden is not friendly to a Pizza oven - that's sad!
you got my vote!
phammy57 (author)  Mimikry14 days ago
Thank you for your vote! - I think your oven would survive if you took measures to protect it. Say October time... wrap it in an old blanket and add a plastic cover. Or as one commenter suggests; building a portable base. all the best!
CraftAndu16 days ago
Truly awesome! As someone who has also built a pizza oven I reall love this project!
NICE! It's hard work but well worth it when you start eating!
Fantastically documented! That is a gorgeous pizza oven :)
phammy57 (author)  jessyratfink20 days ago
It is hot stuff!
AussieAlf24 days ago
That's a fantastic outcome there phammy57.
Great detailed documentation with your build, job well done.
phammy57 (author)  AussieAlf20 days ago
Thanks, I'm pleased it's helping people out.
mdsidoti20 days ago
Hi there, I enjoyed reading through your project. Would have any guess at the weight of the completed dome?
I'm interested in the possibility of a portable version mounted to an old rolling grill cart and am trying to determine if the cart could support the weight.
Thanks, Mark
phammy57 (author)  mdsidoti20 days ago
Hmmm... Tricky one. I have seen someone build a gym ball pizza oven on a wooden base. YouTube I think - I can't remember if it was moveable though.

It's pretty damn heavy. I could lift the dome easily although it was awkward 25kg, so I'd guess outer verm dome another 25kg, blanket 3kg, plaster layer 15kg, bricks and mortar 20kg, insulation slab 5kg, fire bricks HEAVY! I'd cast a layer of vermiculite to keep the weight down there (it's another technique I've heard of but not as durable) best of luck
obillo20 days ago
This is so good, phammy57, that I elevate you to the position of Honorary Italian, and therefore render your name in Roman numerals: phammyLVII. You are dead right about the need for FLAME. I'm picky about pizza and every timer I go to Italy, which is pretty often, I consult with local experts about best pizzerias, then visit them and, between bites, seek wisdom. So far, all agree on flames. Inm fact from personal observation I'll say that the flames must not only dance, they must WALTZ. Slowly. Also, the inner walls of the over should be coated in white ash. Again, congratulations.
phammy57 (author)  obillo20 days ago
Thanks for your kind words from one experienced pizza eater to another ;)
DavidL66921 days ago
Very nice. I've been looking at doing the style with bricks as the dome but the ball mold seems easier.

Question, how long does it take for the oven to heat up?

How quickly can you do pizza back to back? I have a portable oven and my biggest problem is the stone loosing temps between pizzas.
phammy57 (author)  DavidL66921 days ago
It takes at least 1 hour to get really pizza hot. You do have to work a bit to keep the fire going which is tricky sometimes when you're also making dough and sauce! It has been known to still be warm in the morning though. Top tips: Very dry logs. Pre heating logs at the opposite side of the oven to the burning fire. Have the door slightly open to draw more air into the fire.

My dad has a portable oven like yours and whist it heats up really fast it doesn't hold heat as well as this oven. It's due to the density of the materials and their capacity to store heat - hope this helps.
my oven is one of those Unni Pro ovens. Gets really really hot and can cook a pizza in 60-90 seconds... but the stone loses temp between pizzas so I have to let it heat up the stone a bit.... although now I have a gas attachment for it so it seems to work better (only did one round of pizzas).

But I still want to build one of these!

Thanks for the reply.
phammy57 (author)  DavidL66921 days ago
I didn't actually answer the question... Back to back. I put pizzas in one after the other - as fast as people can prepare them!
phammy57 (author) 22 days ago
Just to be clear... You need to remove/ excavate some soil to allow for the hardcore and scalpings material. ;)
You said a 6:1 vermiculite/cement ratio. Is that correct? Then you said a 4:1 sand/cement mix was weaker. Just double checking to be sure I understand the ratios. I’m going to send this to a friend who wants to build a pizza oven. I love the idea of using a gym ball as a mold! Thank you for this instructable!
phammy57 (author)  Daisytikityke22 days ago
The weaker ratio is correct for the brick laying of breeze blocks although you can use stronger if you like. For the vermiculite mix I do recommend 6:1 which is relatively strong for the vermiculite mixture for the dome. .. I've heard of people using 11:1 verm to cement but I wasn't that brave and went for something stronger. Hope that helps and if your friend has any questions, I'd be happy to answer anymore questions :)