The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Wood and/or Gas Brick Oven "help!"

Mini Oven's picture
Mini Oven

Wood and/or Gas Brick Oven "help!"

Working on a oven building project, my first.  About to send off some fire bricks/parts for a wood or gas brick oven and need some input.  

I have to get something into the container at the end of next week for the shipment and need input.  Clay, broken pots and rice hulls will be there.  Tropical, in a camp and half the year is rainy.  Also any steel and concrete works, base and hut are there where I'm building the oven.  Right now my main concern is with the oven itself.  I haven't got the brick or shelf sizes or flue sizes yet.  What I'm needing is the physics, height of openings, chamber, door.  If rock wool is needed what kind and how thick.    thoughts... comments... ideas... where to put a gas flame entrance and if I have to stack 4.5 cm thick shelfs (40cm x 50cm) on top of one another for the baking chamber (for lack of bricks)  does the space present a problem.  

Am I asking for too much time to heat up an oven with a 4 inch or  10cm thick firebrick walls  as compared to one with 2 inch or 5cm walls?  

The drawing I've come up with:    each tiny square denotes 10cm 

 side view  and front view

A is the door opening  

B is the flue opening between baking chamber and chimney  

C is the chamber outer shell (or all the stuff on top of the bricks to seal and insulate then decorate)

D is under the baking chamber (not to forget to insulate)

E is the flue

F  is the flue control (manual) by pushing in and out a slab of fire clay, can be also smeared with a little mud to seal tight after heating chamber  two create a "dead air space"

G  is gas portal waiting for a location

Baking chamber is 80cm wide  x 100cm deep and 35cm tall in the barrel shaped middle.  

Thanks all!    

Comments

Mini Oven's picture
Mini Oven

for baking both pizzas and bread.  I had the hardest time picking the size of the oven.  I might not be the only one baking and it should stay warm a long time if the heat stays trapped in it.  I was figuring  4 to 6 large sd miche  4kg loaves (not wider than 40cm)  Door opening height is 25 cm x 40 cm wide.  Do you think that opening is tall enough?  The shape is basically like the fire chamber of a sauna oven used to heat lots of rocks above it. I have a similar wood burning stove/heater in the kitchen.  Once the fire is out, the flue is closed off preventing the heat from escaping the oven.   Opening "B"in the flue bottom is a big question as to the height, size  and getting the draft correct with corresponding control of air.

I'm off to the brick people now to see what they have.  (I would love it just to stack them together like lego and see exactly how many bricks I need to line the oven and flue.)  Maybe there's an app for that.  :)

My mind is going in so many directions.  

Mini Oven's picture
Mini Oven

Brick size    250/ 124/ 64 mm     or  25/ 12.4/ 6.4 cm   one brick costs €3.48  (€2.90 with 20% taxes)  

In inches the bricks are about 2 1/2 inches thick, almost 5 inches wide and 1/8 inch shy of 10 inches.  

So the Q is... go with 5 inch thick walls, floor, and dome  or 2 1/2 inch thick walls, floor and dome. I was writing a typing a lot of thicknesses and it makes sense to go with the thick thick walls etc.  You guys with your thick brick ovens...  I imagine if the oven is used every day for multiple loads, the thicker one is better?  correct?  It will never cool down.... are pizza ovens thinner so they heat up faster and cool faster?  I have no idea how long a 5 inch thick wall takes to cool down from pizza temp to loaf temp.  Much too Quiet here at TFL!   

Bread1965's picture
Bread1965

The first disclaimer is that I don't own a brick oven. I have taken a baking course to learn how to bake in one. Contemplated putting one in the backyard. But as I live in the centre of a huge city, it isn't going to happen! In the meanwhile I have studied plans on how to make one and have learned a lot about the process.  I have lusted after one. I covet my friends brick oven. Lord have mercy on me! My hope is that one day I'll own a small plot in the bush and build one there for my baking escapades! With that out of the way here are my thoughts.

First, the style of oven to choose from is either pompei or barrel style. The first picture blow shows you a pompei style oven. It is designed ideally for pizza's. But you can cook great breads in there too. It's the round shape that you've likely seen in many pizza restaurants.. I'm just showing you a top image to see the shape and I loved the brick work on this oven. The point of this type of oven is that you don't have any insulation around the top of the oven. It's just brick shaped like a dome. You light your fire, let the temperature of your deck and the dome get up to about 800 degrees +/- and bake your pizza's.. after it cools down considerably, you can throw some loaves in there. It will cool down faster than a barrel style oven - more below.

The second style is a barrel style oven - often called Alan Scott oven. It's better for bread making than pizza making. But again, you can cook both in this oven. The second picture is to show you want the inside looks like (a half barrel).

 

This type of oven will be better for bread as you can control and maintain the temperature much longer. On the bottom deck you can build a sand heat sink, or use insulation and once you have the first layer of fire brick for the dome then you can put up six inches of insulation. and then cover the rest with bricks or a frame to decorate your oven as the picture shows. But you really should insulate if you're going to go to this trouble. It will let you maintain temperature for hours. You can even get the internal oven temp up to 1000 degrees with a roaring fire and put your hand on the outside and not feel the temperature at all if well insulated and constructed.

So as to which style - it's a function of what you like to bake. And given your participation on this board it's obvious that you should build an barrel style oven.

But wait - there's more! You should put temperature probes in the concrete of your deck and dome. This will mean you can fire up your oven and know the temperature of the deck or oven. Or of course you can get one of those temperature guns you can us to point at the inside of the oven and measure. I like the probes because you can take the temperature of the oven without opening the door during a bake. Here is a link to them: http://goo.gl/nifIiI and they will link up to something like this on the side of your oven. http://goo.gl/mI1iku  

The next issue is : how big?! These ovens, especially the barrel type, will take a long time to heat up. You have a big mass to warm up over a few hours. The benefit is that, when well insulated, you'll have an oven for days - yes days - if you time it right and have built it well. You'll have to mange the decline in temp and plan your cooking (they're not just for baking!). So my advice would be to not make it too big. If you would rarely use the bigger size, then don't make it too big. If you normally bake four loves at once, put them on a table in a fashion you would bake them in an oven and measure how much space. That will give you perspective. Or something like that.

Lastly, take a look at this site. It's a great example of a well thought out oven building project!

http://www.frankiegsoven.com/oven-construction.html

Good luck. Have fun. Post pictures!

 

Mini Oven's picture
Mini Oven

direction, thanks for the input and I think you are right.  I am also keeping the ceiling low, as low as I can.  I'm at 35 cm or just under 14 inches in the middle.  Too low?  It's great for measuring for my drawing.  I'm beginning to settle on 80cm wide and 1 meter deep.

I have an arched doorway to my living room (been staring a lot at it lately) that is in a 80cm doorway.  It has just the right curve.  My husband and I made it ourselves years ago.  I might even have the wood brace in the attic somewhere.  

What I'm afraid of is that I'm trying to "re-invent the wheel" with my oven flue.  Maybe I should go with the flow of putting it at the front instead of the back...   

Bread1965's picture
Bread1965

You're idea of 14 inches of height is MUCH too short. Think of it this way. The size issue has to do with the baking deck size, not the height. The bigger the oven deck, the taller the barrel height will be. The smaller the deck, the shorter. Take a look at this oven build and look at the back wall and side walls and count the bricks - think if it that way in terms of size. The dome of the barrel has to be there otherwise you're building a rectangular box - not a good idea.. The dome shape helps to circulate heat around the oven.

Also, put the flue at the front. For thousands of years this plan has worked. Also, when you put the door on after the oven has been cleared out of ashes, you keep the chamber warm. If you have the flue connected to the oven and not able to close it, you'll lose heat. Lastly, your door should be about 65% of the height of the dome height - more or less. That's the proportion. 

 

 

Mini Oven's picture
Mini Oven

I've soaked up lots of detail the first time I looked through the photos, and again I keep seeing more detail every time I do. Did you use a table saw with a wet cutting diamond studded blade?  And did you have problems with bricks breaking while cutting or while chipping? 

Your pictures showed me how easy (and fun) it is to make the arches and walls.  I can easily see myself doing this project.  I can also respect the amount of work put into it,  the support, oven brick cutting, assembly and the detail in the outer housing.  So much to think about and plan.  

 I haven't yet figured out the part with the hood exhaust but plan to use local bricks instead of the fire bricks so will get to that part after the shipping.  I might grab from here, a flue and cap to add above the funnel shape brick flue.  Starts out wider than the door and narrows eventually to a pipe diameter as it cools and rises.  

The plan in my oven roof is to use the barrel arches 4 rows of 8 bricks with the bricks resting partially on front and back walls, and fully resting on top of the side walls (connecting 8 bricks have the lowest corner cut off.)  With each brick weighing 11 lbs, I can see the importance of a sturdy arch support.  Tempted to use screws instead of nails in case I have problems sliding it forward, I can understand that bricks & smaller boards wedging it up to height make removal easier.  

Mini Oven's picture
Mini Oven

and the similarity to Frankie G's oven brick work is astounding!  This is the drawing I did last night of the dome with hints of front walls and opening...  The inside of the oven is marked below the drawing, marks are 40 cm apart.

You can see at the top of the walls where the arch meets the wall, I have a problem with a wedge shape at the outside corner (I just drew in an extra brick... wonder if a brick can be cut the long way.)  In the link it looks like he used regular red brick wedges in those spots.  Frankie's got about the same number of brick in the base and the arch as I drew.  (not bad!)

I have a meeting Sat. afternoon with a professional oven builder, a "Hafner Meister" for tips and tricks.  I explained what I was up to and he has lots of them for me...  So I'm busy compiling my list of Q's.    I might be able to buy thermometers from him and even a door inset if I'm lucky.  Fire bricks here are called Hafnerziegeln.  Especially interested in gas heating blowers etc.  Should be interesting.  

:)  Mini

Bread1965's picture
Bread1965

I should have also mentioned that if you are going to build an oven full-on, then be considerate of the weigh of the structure. You're going to have an oven and structure that will be super heavy. You should build yourself a big concrete pad on which to build your oven. Maybe something with six inches of gravel and then six inches of concrete on top of that.. make it big enough so you can walk around your oven. Have fun!

 

Mini Oven's picture
Mini Oven

good point. (did you mean also around the floor edge of the oven?)   I think they will have to move it (should they ever) with a crane.  I'm sure the oven will weigh at least a ton.  I already have an oven brick base of 93 bricks and as my drawing grows, so is the weight of the bricks.  

Sand and gravel is there. I've heard at least one pottery is also within half an hour. (Tropical potteries are often set up on deposits.)  I might have to make a base under the base to keep it from sinking into the muck.  :)   

I'm sure to get some involvement from others already on site.  Hubby says a handful of Germans have been driving 4 hours to a "real bakery."   

Bread1965's picture
Bread1965

Once built.. This oven is staying put. It's going to be so heavy and trying to move it with a crane will likely end up cracking it. If you think you'll have to move it, don't build it yet. As to the base, I mean that you will see many ovens on the web where they pour a concrete slab for the oven but not for the people that have to work around it and walk around it.

Mini Oven's picture
Mini Oven

I don't plan on moving it, once it's up.  More than likely put up a pole barn around it (tin and thatch roof)  and have a decent platform to support and work on.  Not to mention an open tiki coffee bar atmosphere to escape the hot sun, pouring rain and bake under.   If it does have to be moved (and things like that happen at construction sites) an extended edge on the upper reinforced oven platform would make it easy to use slings or a steel lifting frame to lift it off it's brick pedestal.  You've got me thinking about that pedestal... I think i'll make it with a "hash tag" form (#) it will be stronger and no rod going up from the pedestal into the slab.  

yozzause's picture
yozzause

A great site for most of those questions is www.traditionaloven.com Rado is the man that we got our cd for building our oven that has been pictured on TFL in the past. kind regards Derek

Mini Oven's picture
Mini Oven

links and info.  Just what I'm kneading to know.  

Also how happy are y'all with the width of my door opening?  I was drawing up 40cm or  15.7 inches and can easily go to 50cm  or 19 inches.    

Guess I should measure a cookie sheet...( 33 and 39 cm)  But I'm wondering what the actual sizes are and do you wish it was wider?  

Bread1965's picture
Bread1965

You should easily be able to put in a cookie sheet with out fussing. I wouldn't go past 20 inches.

A 19 inch opening wide, 12 inches tall would be good. Your dome would be about 20 inches tall and the depth of your deck would be about 42 inches.. more or less..

Have FUN!

 

dabrownman's picture
dabrownman
Mini Oven's picture
Mini Oven

always a tweak or two....  :)

EdfromWdstk's picture
EdfromWdstk

Hi, Mini-

You may already be aware of this link to a very helpful page with great pics and details re a build of an Alan Scott (http://www.considine.net/mac/brickoven/)- which I found to be extremely helpful in my build of a Scott Oven. The Alan Scott- Dan Wing book -Breadbuilders- was very helpful also. We attended a Jeff Hammelman WFO class last fall @ KAF- and he made a strong recommendation to consider the French model -approach to building WFO ( I forgot the term for the type) - that has a firebox below the chamber- with vent into the baking chamber that is manually opened when heat is needed, etc. It occurred to me that this alternative may lend itself to a gas fired-oven- that you make mention of. I also am not certain I see the benefit to the internal - rear flue. If it is to allow for a better draft-air flow for firing the oven- you might look at the Frankie - G site (store link) and consider the adjustable metal venting plate that can be used at the opening to create a helpful initial burn draft. The one thing that I would perhaps do a bit differently if I were building my Scott wfo again would be to put more insulation in beneath the hearth. The ceramic fiber rolled sheets that are now available are worth considering in lieu of loose poured vermiculite etc- over and under the concrete clad chambers. BTW if you are planning to use thermal coupleto measure heat- I bought 3, but did not end up using the same-and would be happy to give these to you for your use- than see them go to 'waste'... just relay contact info etc... Good luck and have fun!

Mini Oven's picture
Mini Oven

kind offer of thermal measuring devices.  I might have to turn you down, Sorry.  Thank you so much.

The oven builder I've been talking to says the wool like fibre (my words) I think it's what you are talking about, is his insulation of choice.  Also for voids, not vermiculite.  I will find out more later this week when working with my bricks.

I asked about special gas equipment, he is more in tune to WFOs but says a long nozzle gas welding torch can do the job easily just aiming it into the oven thru the door.  Will have to check that out with my private expert.  I can't imagine doing that for half an hour to an hour.  Maybe he thought I was joking.

Bread1965's picture
Bread1965

Mini - just to be clear. Is your oven builder suggesting asbestos with the term "wool like fiber"? If so, be careful. While you could make an argument that this mineral once sealed within the chambers of your oven is safe, I would never build with it. It's highly carcinogenic. While I don't see how it would touch your bread, etc. I wouldn't even want to handle it. And if this is what he uses, you should consider a word of caution to him. If it's not, great! Let us know what he has in mind!  Also the comment Ed made about firing under the chamber is called a "white oven" vs black of course - because the chamber itself never sees fire or ash. It's a good solution too. I'm skeptical about warming the oven through the door though. Have fun!

Mini Oven's picture
Mini Oven

Can't even find it here and it is forbidden to use it or build with it.   A little known fact,  the insulating tiles on the space shuttle were made here in Austria.  We have a great variety of insulation here.  

My oven builder did tell what it's called Calcium Silicate and assured me it's not Asbestos or Fiberglas.  It is very strong and light weight (comes in big sheets, cut to size)   and there is enough to box in the main firebox of the oven.   A wool over the top of the arches.  I am also connecting the arches differently, instead of lopping a corner off the long side of the end bricks (8) It has been suggested that I cut a "V" into the top of the wall bricks to add extra stopping power to the arch as it expands when heated.  That wedge then gets used on front and back wall joints to add thickness.  

After everything is bricked without mortar, the oven gets smeared on the outside with a slightly elastic high temp mortar and a glass net gets pressed into the coating to seal cracks and hold the bricks in place. While still wet, the Calcium silicate panels get pressed onto the brick.  I can add foil if desired to the outside of the insulation and then brick up a decorative facade.   Any extra bricks left from construction (I ordered a few extra) get set into the front wall for more thermal mass around the door opening.  I also threw in two lengths of steel pipe for an extended chimney.  d 18cm.

Although I was bent on having oven bricks in the base, I got talked into the layered slabs (8 cm thick) in the oven base.  He, Albin Freinberger, says the bricks work but tend to catch the peel and chip the brick edges.  He recently replaced the floor of a commercial pizza oven after they had a lawsuit.  Broken tooth from biting chipped oven stone that stuck to the bottom of a pizza.  This chip of stone came from the oven floor about one foot inside the door.  Albin conveyed this is a very well worn spot in many ovens.  I don't plan on using it that long but I wouldn't want to get sued or break anymore teeth.  I suppose that puts in a good word for wooden peels, they are less apt to chip the oven floor. Replacing the peel every few years is more economical.   

Was looking this afternoon at the new enamel-ware baking forms.   So lovely!  Glossy black enamelled steel with tiny spots of white.  

 

Mini Oven's picture
Mini Oven

back up and start over trying to fit the bricks in with as little cutting as possible.  Still managed to have 17 bricks I need to take a big diamond grinder too.  That's too much muscle for me but I'm sure to find someone.  Only 17 little tiny bricks.  

I've gotten a few things straightened out and ready to have my plan looked over by the local expert.  The bricks are  250 x 124 x 80 mm    The platform under the oven is 108cm x 100cm and I played with the flat lying bricks until I like the pattern. after all, I'll be looking at it and the back wall for the next few years.   The base contains 36 bricks (put one on the scales and it is 80g shy of 5kg.  wow  Got my bricks down to 102 w/o extras  102 x 5 kg is.....510 kg or half a metric ton (1000 kilograms)  double wow.  

I'll be putting it together in the shop (where the bricks are) to make sure everything fits.  If I didn't have a grinder there, now would be the time to cut those 17 bricks so everything fits nicely at the destination.  I even worked in all the scrap cuts. If I don't break any bricks (I don't know how easy that is) there is almost no waste.

Ok, 36 bricks in the base, 34 bricks in the walls and 32 bricks in the vaulted barrel roof of the oven.  I think putting it up is the fast part, making the base and the outside housing of the oven, that's the part that takes more time.  The door  opening is 28cm high and there fore the required chamber height is at least 10cm more  38cm for optimal heating and circulation.  I found out that inside shape is not so important as every brick will radiate heat be it round or have corners.  A lower ceiling is important if a lot of pizza baking is going on.  

Pizza ovens don't need doors and have "chimneys" at the front, can have inside or outside flue, the difference is the price of the flue closing mechanism.   Bread and roast ovens need doors and regularly have the chimney at the back with adjustable/ closing flue. (My drawing needs more baffle if I were to have a rear inside flue.)   As the door opens, the flue closes down to prevent draft and heat leaving the oven.   Maybe you've noticed pulley or cable devices around such ovens. Flues can also be closed manually.  So my drawing is not so far fetched but it does complicate the brick works.  Too much so.  A front chimney can be used for both pizzas and bread. But if pizza is not a priority, there are other options than the front smoke exhaust chimney.  I will be building my oven with the exhaust in front, for pizza, bread, roasts and other food.  Good to know why.

Bread baking brick ovens can also have glass doors with vent control and be double decker.  The glass doors with iron frame look classy but tend to be half the price of the whole oven. (Does anyone think about cleaning that glass?)  I might consider something showy or decorative for the long haul to keep the critters out and perhaps lock it for safety reasons.  I think I'll pass on the expensive door this time.  So a simple door that doesn't burn up for baking is a good solution.   I think a firebrick shelf ground to fit inside the door opening, mounted to a wood board with space between and bulky wood handles might be my first try for a door.  First I'll wait to see if my bricks make the trip.  Might put wood directly onto the shelf, on both sides to ship.  I thought about soaking the wood door before baking but worried about water contamination in my baking space.  

Did get some great tips on shaping the bricks around the door opening without having to use, corner iron. (I think that's what it's called.)  One probe thermometer, a whopper compared to the little thing I stick into some of my loaves!  That's all that's needed, a copper tube goes in the upper ceiling crack mortar only part way into a space between blocks. I'm not even sure I need it but because there may be more people using the oven, it makes a good reference point if someone  hasn't been watching the oven very long and simply wants to know how warm it is in the bricks.  It only starts showing temp as temperature falls down to baking range from heating up the oven.  

I'm also very curious what local rocks, bricks and other interesting materials are there that could be used for the outside more decorative walls of the oven.  I also have a location inside the oven, on the back wall, where one of the firebricks could be chiseled and featured.  Might be a cool hot idea to see how the flames make it dance.

Did I mention using rice hulls mixed with mud/ for insulation?  I think it Important to get it very dry (and keep it that way) before piling on any layers and building on top of it.  If I can get several layers of locally fired bricks made with lots of hulls and crushed pottery (grog) in it (think crumb shot of fluffy cement) that might make a good sturdy insulating base above the base concrete and below the firebrick oven.    I thought about unfired bricks but that might absorb too much humidity in the rainy season and turn into a mass of wet mud with no trapped air. Dry, sturdy and trapped air pockets, that's what I'm after.  I've also got a mineral wool (not asbestos) for insulating.  

Oven mitts... any thoughts?  Armpit length?  What about installing a shower or plunge pool nearby to cool off the "baker?"

Bread1965's picture
Bread1965

This sounds like you're on a great adventure ! Post pictures along the way for us to enjoy your journey!

Mini Oven's picture
Mini Oven

at least on paper?                  

 The numbered bricks (1,2,3,4,5,6 & 7) get cut along with the end bricks on the roof.  If I can do it I want those top end bricks to have a "L" cut so there is more thickness to the joint.  Maybe I should explain that the roof is 8 cm shorter than the length of the oven so it rests on only 4 cm of the 8 cm thick end walls.

Hubby said he wants to be able to pick it up with his 40 ton crane.  :)  Boys!

(I some how knew he would.)

 

Mini Oven's picture
Mini Oven

to the container today.  Loaded on a pallet is everything I need for the guts of the oven.  I will somehow make a back portal for gas if needed plugged with a brick (later.)  The 5 cm and 3 cm stacked slabs plus a row of 4 bricks make up the floor of the oven.  Mortar is double wrapped in heavy plastic to keep out moisture, special brick hammer is included.  I'm tossing in my Giant bundt pan, Walmart 3er rye pan (lasagna pan)  parchment and a small swimming pool.  I think everything else I need will be there.  We shall see and a little adventure finding stuff and using my grey matter (and taking pictures)  is a welcome activity.  There is an internet and a water purification plant has been built.  (my second and third biggest needs)  (4th) Flour?  ...to be continued.  

Gotta ask if there is a "grain" to the fire bricks...  

Mini Oven's picture
Mini Oven

So frustrating.  I have time to put up my oven now but hubby built a garden wall across my planned site slicing it in half.  Decided garbage cans could sit on my concrete foundation.  :(  Think he's trying to tell me something?  He's pushing a build by the fancy water tank.  (see the oven road blog post)  

I'm tempted to build my oven now with a whole new concept.  Will shift a few meters (to avoid the trash cans) and build  backwards from the front of the oven to the back of the oven by first cutting a hole in the wall.  That would mean putting the whole of the oven outside the garden and just having the oven opening in the garden.  Hmmm.  

In the garden, one would only see the door and its surrounding bricks... and the thermometer dial.  (and a big flat wall)   That would actually work nicely come to think about it.  There will be a slightly longer neck at the front of the oven, The wall is 18cm thick.  I can empty ashes from the back after dropping thru the ash drop and the chimney pipe can be attached to the outside wall for support.  Gotta plan this out first.  

 ....The Garden Bakery...