I had been wanting a pizza oven of my own for some time... I currently rent and cringe at the thought of building something and leaving it behind. So after much stalking around and youtubing i finally put together a plan to make something that is moveable (i don't say portable, i don't plan on taking it tailgating), lightweight, uses fire bricks and uses wood to cook.
I had seen a guy on youtube who built a oven using crushed pumice stone and portland cement with great success,
but he used a exercise ball as a mold, which i thought was pretty genius... and I had one collecting dust.
If the youtube video does not work the guys user name is: JJGrice018 you can get an idea of my inspiration.
So after a little more research I decided to do a perlite/portland 5:1 mix with Stainless Steel Needles added for strength... I also planed on adding in firebricks so the pizza could cook on that surface. (Perlite and Vermiculite are 2 totally different things but they are usually next to each other at the Home Improvement stores. Perlite is volcanic rock, puffed up through a process so it is super airy, used in Ovens, chimneys, so on.. Vermiculite absorbs water and your oven could explode... no joke)
There is a lot of very specific info about dome (inside) height to door height ratio... apparently the magic number is 63%, this was established by a bunch of scientist that studied ancient wood fired ovens. So lets say your dome height is 10 inches, your max door height should be 6.3 inches (63% or darn close). To high of a door and the heat escapes and the top won't cook at the correct speed and be under cooked, to low of a door top burns before the bottom is done. I did not create these formulas but it seems to be very specific and backed up, so I was pretty surprised that some big companies that i looked at for design ideas did not seem to have these ratios... so i took a little from 4 or 5 different design to get my own..
So here are the parts of my build:
1. Top Dome Mold/Cement
2. Bottom Floor Mold/ Cement / Fire Bricks
3. Finish Work / Detail work on Both Pieces
4. Table stand / Pavers to sit on
5. Put the Pieces together...
So here is my build.. exercise ball and all.. enjoy and tell me what you think!
Here is my price sheet build....
*Forgot to add this on previously 3x5 .5" thick Cement backer board Durarock/Fireboard $9
Perlite $17 x 2 = $34
Portland Cement $9 x 2 = $18
SS needles $28
Fire Bricks $0.90 x 25 = $22.5
Pavers $1.58 x 9 = $14.22
Chimney 4" x 2' = $4.50
Exercise ball... i already had
plywood I have a ton of.
Sweat... plenty to spare
Step 1: Top Dome Mold Build
So after inflating my... WIFES... exercise ball.. i measured the circumference to figure out the diameter for the circle cut out. After a high school flash back, you take your CIR measurment divided by pie..3.14 and it gives you the Diameter. I cut out my circle inserted the ball and BOOM.. inside dome created.
*FYI-There is an image that shows a bungee cord around the bottom of the ball.. I had a fear of laying concrete on the top and the ball slipping through... I never used the bungee cord and I just simply inflated the ball slightly more, essentially wedging it.
Then it was onto the door mouth entrance. So with my dome height of 12.5 inches i went with a door height of 7.875 high, remember the ancients, trying to aim for a 63% ratio. I wanted to be able to pull the ball or deflate the ball from underneath so I wanted to pull out the door mold as well. So here is the set up on that. One thing I can say is take your time. Just like a lot of things that you create that translates to many stages later in a project, the devil is in the details. Take your time to make those things fit better.
I had some trial and error on some things..like the white legs you see under the platform, they sucked and fell apart. I got them from my neighbors trash. Also I never thought it through until i was about to put concrete on the form, supporting the plywood/mold. When your messing with it, pretty much anything can hold it while you play with it. Then it dawns on you about the weight and awkward shape you have to support from underneath.
Once the mold was ready or so you think, its time to just say go for it and mix up concrete..
Step 2: Concrete Mix and Molding to the Top Dome
So the mix I went with was Perlite/Portland Cement. I also added Stainless steel needles for (fiber) strength. Perlite ($17) and Portland ($9) from Home Depot, SS needles from ebay ($28).
I used a wheel barrow and your standard hoe with a chop chop action. I started with 2.5 buckets of perlite and .5 buckets of Portland Cement. Mixed together well. Then I added the SS needles, i saw online that someone said about 5% SS needed. I purchased 10lbs so i figured about 4 lbs should be plenty. I hope that over use is a overkill not a issue later.
Once it was mixed well i added about a half bucket of water and kept the hose close to sprinkle additional water as needed. Don't forget that once you have water in your mix, add very little water carefully a little goes a long way. If you add to much water you can always throw some additional dry into there.
If I were to do it again, I say this now, but at the time it seemed like a lot of extra work, I would have NOT used the ball as a form. Yes it did work. Yes it does look great. The thing i didn't like is that I had planned everything out including the dome thickness and wanted to keep it at 2 inches. I even made a gauge to ensure proper thickness. But once I started to carefully add the material it just could not support itself going up the sides of the form. The top held, and the bottom/ sides up about 4 inches, any higher it would just slide down and thicken the bottom. Also the material feels very odd if you have worked with concrete before, the perlite makes it extremely light, airy and you feel the need to try to "compact" to the wall and the BALL gives and moves. So if you apply to much pressure the rest of the ball bulges and you see material moving. So with that being said, I might have put plaster on the ball, made a positive mold, and then transferred to a negative version of it. I didn't take any photos of the "during" process for a few reasons.
1. Sweating my butt off
2. Frustration trying to keep it from sliding all over.
3. South florida 90 degree weather, did i mention sweating my butt off?
In the end the bottom walls are about 3 inches thick and the sides about 2
Step 3: Finish Detail on Dome Top
So after I had explained that you couldn't really push or compact the mix to aggresively or the ball would just give and bounce. After a day of curing I noticed one spot the size of an eraser head that i could see the ball through the wall. So I decided to skim coat the outside and inside. I skimmed the outside and after a day of curing I removed the molds.
I had been trying to figure out the best look for the outside and after I saw the results of the mix i decided to use some of the portland cement and some SS needles to skim the inside and outside. It came out looking pretty good. Just remember, water is the enemy. Use sparingly. Obviously you want the proper amounts to create the cement to the optimal mix, but try not to use to much water in smoothing and what not. You'll find that water might make it easier to smooth out the surface, but the right timing on the concrete ( about 5 minutes after applying) and some elbow grease will do the same thing.
So for the inside and outside i just applied a light thin coat of the Portland and SS needles and made sure I took advantage of the stiffness and worked the mix into any holes.
Step 4: Bottom Floor Mold
So the top is done. Now it is time to work on the bottom. Almost all the ovens i saw used either a large terra-cotta tile or a pizza stone on smaller ovens. I wanted fire brick. I wanted it to look nice, serve a function and be replaceable if they crack over time so they could not be "concreted in" like you might see on some larger ovens.
Also it is important to lay your brick floor in a herringbone pattern. Reason being if you lay your bricks parallel to the door, when you slide your peel in you run the risk of catching or chipping a front brick edge. Not good and don't taste good either. Besides herringbone screams quality.
So i slid to top dome onto a piece of plywood, traced it out, then took my original circle cut out that i cut out for the exercise ball (giving me the inside circle of the dome) and had my two templates.
My fire bricks are 8.25L x4.125W x 1.25 Thick.
I wanted a total of overall thickness of 2.25 for my floor. So the outside tracing I did of the (footprint) of the dome was by bottom. I attached 2.75" (2.25 for total thickness of floor, and .5" so I could screw it to the edge of the plywood template) tall trim pieces of formica around the entire edge, stapling and screwing. Then I took my inside circle and the inside of the door template and put a couple of pieces of wood to hold the inside circle in place at a 1" higher than the floor... Confused?
So the idea was that the main bottom template would get concrete up to 1 inch high / thick, then i would insert my inner mold in the enter and that would represent the space where the fire bricks would later go, and fill concrete the rest of the way, so the bricks would later be even with the rest of the floor concrete... please see pics..
*Please don't forget to put in the SS needles like I did. It seems to be a little brittle around a few edges because of that.
Step 5: Firebrick Floor
I wanted to lay out the floor in a herringbone, so that way it would not catch any edges putting in or out pizzas. I wanted to start with 3 full sized pieces at the entrance. Peel can easily clear the first set. I didn't want to have any crazy cuts but i ended up having 2. I have laid tile in the past so i did have a little experience here, but the great part is that you can basically lay the tile on top and make a few marks on the tile and do the cut.
I started with a few rows down the middle and worked my way out from there. In all you want a tight fit and you'll find a few bricks cut darn close and shoved in will kind of lock it all into place. Don't over force it or it can break or damage something.
Step 6: Bottom Floor Detail
So i later removed the bricks and did some fixing (brittle chucks lost due to no SS needles, so i think anyway) and skimmed the edge to give it a cleaner look. So once i skimmed the edges i came back later and smoothed and cleaned it..
* I previously forgot to mention this step due to having no pics of it..
I had traced an outline of the footprint of the bottom section of the oven onto the cement board. Cut it out and mixed up some portland cement and used as a glue to put the bottom section of the oven onto the cement backer...
I THEN added the skim coat to the walls and the cement backer edge... making it all look like one uniform section..
Step 7: Stand and Pavers Base.
We had our spot picked out for some time. I tap-con(d) the heck out of some pressure treated wood and sunk some 4x4 into the ground in the front of the table and used 2x4 to make a platform. Over build this. My pizza oven is only a few hundred pounds but i figured better safe than sorry. I think my platform was 45 inches long and 36 inches deep. We ran supports 12-15 inches and used 2 inch thick decking a neighbor was throwing out.
You see from the pics that we do have it slightly turned. We have a vegetable garden right there and it looked better that way any how.
We also added some pavers for the oven to sit on. It seemed some opinions varied on the amount of space but you basically want at least 3" of concrete or insulation if you have it on a wooden platform. I have seen people use less and more but 3" seem to be the common number. So we laid down pavers and I used my bottom section wood template to make my mark.. and cut to size. Look good no?
I didn't take any pics of it, but we put a strap around the pavers so they wouldn't move around and brought the base over and laid it on. Then we put 1 brick/ pavers(need to be slightly higher than the floor) at each corner (4 total, 2 at rear and 2 at front) and laid round pipe or a wooden dowel. I then mixed up a small batch of portland cement and SS needles and troweled on a thin coat on the floor base. I basically used it as a "glue" for the two pieces.
(* I did not take any pics of this process, but I added a pic with the firebrick floor so I could explain. It is the perimeter surface around the fire bricks ((Not the front door entry curve)) that 3 inch border)
We then brought over the top and carefully put on the dowels or supports that your using spanning to the bricks. We then aligned it and lifted the rear, slid out the dowel and carefully lowered. Then did it in the front.
Holy CRUD.. they are together!
Step 8: Just a Few More Details....
Then once they are aligned it was just a skim coat around the outside to seal the seam and my wife did all the detail work in the front.
I never would of had the patience my wife did to really make it look fantastic. If there weren't the pics to prove otherwise floating around with family I would have claimed to have done it myself, but really i was taking pics and drinking a cold beer.
Obviously it has not been fired up yet, I think we are going to wait about 3 weeks to make sure that we are good and cured. Just stick your face in the door and smell. If it smells damp or wet get it a few more days.
To fire cure it... START SMALL..... do not put a roaring fire in there right away...
After 3 weeks we plan to do a small fire (2-3 twigs) let them burn completely and die out.
Then repeat the next day with a medium fire (3-4 twigs) burn and die out.
Then another medium fire... but add to it to keep it at a medium fire for an hour or so
Then another medium to larger fire, burn for an hour....
Then you should be ready for a nice roaring fire.
Any cracks that occur you can fill later once they oven is broken in with the Portland SS mix...
When you get your fancy new pizza making equipment be sure to get a thermometer to keep an eye on temps.
Let me know what you all think....want to hear your ideas and see your ovens... Thanks ALL!
Step 9: Few Additional Photos I Thought Worth Looking At...
Took some additional photos that I thought were kind of important. The door opening is about 12.5 inches wide. I absolutely feel that is plenty.. like i had mentioned before, with 90 second cooking times one pizza at a time is perfect.
Also I wanted to show the inside lip (where i get my 12.5" inside measurement), the reason for the lip is that is what my door will rest against. The door will eventually be made so I have a few weeks to get that done.
I will be doing the door in the next few days.. I will try to take some really detailed pic in the process and I noticed that I can do video as well so I might attempt that.
So be sure to follow and you can see the concrete process.. its just the door but you can scale up from there.
P.S. I have already begun putting 3 other projects to fruition. These are projects that were doodled on the same yellow note pad with the title "Pizza Oven" that my $135 Pizza Oven came from... so stay tuned..
Step 10: Just an Update
So I have had a few questions, sorry for the absence... my new business has kept me pretty busy also I have tried 3 or 4 times to make dough (2day process) and then when getting the oven fired up running into issues with rain (south florida) but i have done a few things in it, but didn't take photos. I am planning on doing some christmas eve dinner items in there so will be sure to take some pics..
Great things to mention: Just as a REAL or Larger pro oven the inside roof gets nice and white when it is at temp.. just like the old guys say to look for, the inside roof and crown turns really white, a sign that it is time to start cooking (700-800 degrees)
Here are a few things I would have done slightly different:
1. I would have treated the outside after a 30 day cure, and a few firings just so the rain and weather would have made it a little stronger on the outside. I don't think it is an issue, but i did notice after a rain, it would have a slightly darker color on the outside for a few day, like it had intact absorbed some moisture. So I would have sealed it or something like that.
2. Also instead of using the ball, I mentioned this before, i would have used the ball to make a form or just made a stronger round from. Issue being when I started to build the concrete mixture onto the ball, it slid around and also when you pushed into the ball it would move and give. So having a more solid surface would have been nice.
But all in all, after a few firings, and i have indeed cooked a few things, pizza, wings so on, but forgot to take photos. I would like to see any improved versions, that you guys can conjure up. Also I hope i have answered most of the queries that you have had. Let me know.
Here are some updated photos that i took moments ago to show what it looks like now from the original build to now... It has been fired up 6 or 7 times, totally cured, and cooked in twice. I also decided to build a small fire in it so i can use it on christmas eve. (wanted to re fire cure it a little because of the wet weather we have had recently) so i will do a few small fires over the next few days just to be safe. I will also seal it very soon as well. I have not decided if I wasn't to plaster, or concrete seal it, the outside does not get very hot so I am leaning towards a basic sealer...