Wanting to build a coal fired style outdoor pizza oven

[Jon in Albany]

Thank you; these are all things I need to think about.  I didn't realize how much weight would be on the doorway steel.  I'll have to see if they have ½"next time I go.  https://www.traditionaloven.com/building/details/concretecladding.shtml had mention of the concrete cladding from that Flickr link.  Interesting how he says to use concrete mix with Portland and lime.  I did always find it strange how people use concrete over the walls and ceiling, since it's job would be to hold heat.  I told your father in law story to my cousin last week.  I use it as reference now for using concrete in heat applications  . That's a good idea about the firebrick turning on the side!  So if I had firebrick walls and roof, would I be able to apply roofing right to the firebrick and I'd have to protect all firebrick walls from rain I'm guessing?

I thought about that yesterday as I held up the angle iron and was going to ask, but I forgot haha, so thank you for bringing this up!  So to make it level, I'd need probably either brick or more mortar in the back I'm assuming?  Another thing is that a downward slope to the back might be good for rain.  Another idea is to use another angle iron on the back wall, to make it level with the front one.  People don't usually use mortar with angle irons right?

Weird, Flickr said they are going through design changes on the site.  Not happy with the timing.

I looked at Forno Bravo again and I remembered the FB blanket with wire mesh and insulating concrete over the blanket.  Also they say "The oven enclosure must be sealed to protect your Pompeii Oven and its insulation from water. It can be constructed from concrete block, rebar and stucco mesh, metal stud and concrete board or free standing brick or stone. Basically, the style of the enclosure is up to you, your imagination, and the availability of local materials. The examples shown here from around the country will give you a start."
Thank you Peter!  I have a feeling Flickr might be a bit unreliable over the next few days.

I think if you add hydrated lime to the mix, that will make the quickcrete paste closer to a homebrew version heatstop, not all the way but closer, however the stones are still not heat rated and the mix is missing fire clay. I think that would be better than straight quickcrete but I dont know how much lime to add. The homebrew mortar is  3:1:1:1 (sand, portland cement, lime, fireclay).

I wouldn't apply the roof the the brick. I'd insulate it to hold heat. I'd insulate the walls too. Cant have too much insulation. If heat saturated, the brick will be 600+ degrees. Not exactly something roofing should be touching. But yes, I'd protect everything from the weather. If the oven gets wet, you'll be driving the water out every time you use it. Things will crack too.

You could leave the angle or make it level. That's a design choice for you. My 2 cents... I think level is better (no experience with your design though) so that the ceiling angles lay flat and have more of a bearing area to transfer load to the walls. Just an a opinion.

[Pod4477]

I think if you add hydrated lime to the mix, that will make the quickcrete paste closer to a homebrew version heatstop, not all the way but closer, however the stones are still not heat rated and the mix is missing fire clay. I think that would be better than straight quickcrete but I dont know how much lime to add. The homebrew mortar is  3:1:1:1 (sand, portland cement, lime, fireclay).

I wouldn't apply the roof the the brick. I'd insulate it to hold heat. I'd insulate the walls too. Cant have too much insulation. If heat saturated, the brick will be 600+ degrees. Not exactly something roofing should be touching. But yes, I'd protect everything from the weather. If the oven gets wet, you'll be driving the water out every time you use it. Things will crack too.

You could leave the angle or make it level. That's a design choice for you. My 2 cents... I think level is better (no experience with your design though) so that the ceiling angles lay flat and have more of a bearing area to transfer load to the walls. Just an a opinion.

Thank you.  haha forgot about hot bricks and roofing touching that.  I bet it's best to follow Forno Bravo's method, which is the same as yours, and they suggest using ½"-2" high temp mortar for added thermal mass.  Then of course the FB blanket followed by concrete or perlcrete.  You already know this process, but just want to make sure I understand it.  Another idea is to just make a gable house structure around the entire oven, fill with perlite and maybe even have a blanket on the oven too.  I'd have to decide if I use metal studs or if I use concrete blocks/bricks for the house. I'm not a huge fan of gable houses, but I'm thinking of the 2-5 ft of snow every year. 

I think level is better too, you're right.  So obviously the most common way to even out the back would be to use more mortar right? But with high heat mortar this is usually frowned upon, so would another ¼" angle iron, mirrored, be the best option?  I also called my local supply shop and that ¼" is the thickest they sell. 

I think the two options are a gable house or do the concrete cladding.  The gable house would require a flue.

[Jon in Albany]

I really dont know what is best here. I know really big heat stop joints aren't ideal. Also keep in mind that I dont think you have the angles going the full length of the front and back walls so you will have a step. I dont think a little step will matter much but it will be there. Maybe a piece of flat stock in areas that dont "need" the angle? Maybe beefier angles that go side to side instead of front to back? I don't know. Fewer but thicker angles might be about the same price as more thinner angles. I dont know how either ceiling ties into the door.

There have to be steel suppliers that aren't too far from you. That metal supermarket would have many angles of varying thickness and legs. Flat stock too. Maybe the door fabricator will sell you angle or point you in the direction of a supplier. I just put "steel supplier in Massachusetts" into Google and got a lot of options.

[Pod4477]

I really dont know what is best here. I know really big heat stop joints aren't ideal. Also keep in mind that I dont think you have the angles going the full length of the front and back walls so you will have a step. I dont think a little step will matter much but it will be there. Maybe a piece of flat stock in areas that dont "need" the angle? Maybe beefier angles that go side to side instead of front to back? I don't know. Fewer but thicker angles might be about the same price as more thinner angles. I dont know how either ceiling ties into the door.

There have to be steel suppliers that aren't too far from you. That metal supermarket would have many angles of varying thickness and legs. Flat stock too. Maybe the door fabricator will sell you angle or point you in the direction of a supplier. I just put "steel supplier in Massachusetts" into Google and got a lot of options.

Thank you.  So I took some pics of my dry stacked rough draft today.  I was thinking of following the earlier models of angle irons running from front to back, but I could also do side to side.  I bought another angle iron for the back and yup with it being not as long as the sides, there will be a little step.  Fortunately the angle iron thickness is ¼" which will be the thickness of the mortar joints.  You can see the gaps in the photos.  The red brick will be the landing/vent.  With two courses on top of the walls, it spans 14" height, with a 27" wide door (can make 24" in the final mortaring" and 44" depth that the ceiling angle irons have to span. 

Priced out at Home Depot they are about $12-15 for the ⅛" 48" angle irons.  Good idea about checking the metal supermarket, as it will be nice to have them cut it exact for me.  I bought a new Sawzall, so I can if I have to, but it's just one more step.  Now do people mortar in between the angle iron and the brick that sits on it?  I assume they don't mortar the angle iron down onto the brick it sits on.  Or do people not mortar any mortar onto the angle iron?  I never really asked and assumed they just stayed in place from the weight.  So in my case for the front and back angle irons, do you think mortar is needed on top of or below the angle irons?  I really appreciate it!  I'm going to try to get all the angle irons in the next few days.

Picture info:
1.  The firebricks in the middle front are there just for storage before the rain, but I arranged them more safely before I covered the oven.
2.  I placed the firebrick sideways for maximum thickness in the walls.  Is this the best way though?  It will cut down on oven floor space.
3.  The front and side walls have the gap that I can fill in with a cut firebrick.
4.  In photo 2, I showed a rough span of the brick, but obviously the brick will be slid over more.  I just showed it to show the gap.

My other idea is that if no mortar is needed with the angle iron, then things should line up with ¼" angle iron and ¼" mortar joints.

[Jon in Albany]

I can't answer your questions.  I have no idea on best practices are for putting angles into masonry. I only used them in my stand basically as stay in place forms for the openings.

Wall thickness is a design question. Your call on what you want. If you are putting concrete all around, maybe the thinner wall with concrete on the outside is an option that gets you similar wall thickness. It is about how much thermal mass you you want in the walls. I can say my oven is about 3 inches thick all the way around (floor, walls and dome). Inusually heat up for at least 3 hours but have baked with about 2 hours of warm up.

[Pod4477]

I can't answer your questions.  I have no idea on best practices are for putting angles into masonry. I only used them in my stand basically as stay in place forms for the openings.

Wall thickness is a design question. Your call on what you want. If you are putting concrete all around, maybe the thinner wall with concrete on the outside is an option that gets you similar wall thickness. It is about how much thermal mass you you want in the walls. I can say my oven is about 3 inches thick all the way around (floor, walls and dome). Inusually heat up for at least 3 hours but have baked with about 2 hours of warm up.

Thats fine! You always help so much, along with everyone.  I'm assuming you would just mortar the brick ends to each other, that are end by end on the angle iron. 

2-3 hours is good!  I think I may have to keep the walls this way, only just for support of the angle irons and ceiling.  The side walls may be able to be turned, but the front and back seem best this way for the angle irons on the front and back.There will be a lot of thermal mass though, but I may just end up using a blanket and percreting over that.  I wonder how high the ceiling really needs to be.  So far I have two courses planned on top of the side walls, which seems best.  I believe that's 14" oven hight/headroom.

[Pod4477]

So I'm trying to decide if I should go with stainless steel angle irons or tee bars for the ceiling.  Not sure if it's worth the extra price, and still been thinking about if I'd need to mortar the bricks down onto the angle irons.  I'm assuming I should mortar between brick ends, but I've read that mostly they don't mortar the brick bottoms onto the angle iron.  In photos from the Flickr oven, it looks like he mortared the angle irons to the brick they rest on (all sides of the angle iron look mortared) and this seems like a good idea. 

My other thought is if mortar will even stick to the angle iron after I oil them up.  Cost wise, Home Depot has the best price so far for 48" Length, 1 ½" x 1 ½" x ⅛" angle iron around $13.  I'd have to double them up and cut them down to 44", but that should be easy with a Sawzall or angle grinder.  I'm going to call the metal supermarket tomorrow though, but theirs seemed to be $20 for the same steel angles.

Forno Bravo also said to soak the bricks, but I believe that was already mentioned in here too.

[Pod4477]

Got more bricks mortared today.  Hope to get a lot more done tomorrow and then start using the angle irons.  I got info that I should mortar the angle irons in.  I'm also thinking of using the high heat Sakrete mortar from Lowes.  Anyone use that stuff?

[foreplease]

hahaha multi quote was tough to figure out definitely; I just quote someone like normal, but then below this text window under the section called "topic summary" you click "insert quote" to the right, to add another quote of a recent post.  Not sure how to do it from older posts though, only recent topic summary ones.

Thanks for your help on this. I’ve been able to use it a couple times now. Seems easy now!


How is that oven coming?
Edit: we posted near the same time. Got it. Glad you are making progress.

[Pod4477]

Thanks for your help on this. I’ve been able to use it a couple times now. Seems easy now!


How is that oven coming?
Edit: we posted near the same time. Got it. Glad you are making progress.

Np! It's a productive way of replying for sure. 
Haha sorry haven't checked this thread in a day.  I almost have the 1st course done; expecting to finish it in 10 hours.  Then I gotta do the angle irons over the door and maybe on the back wall, followed by hopefully finishing the second course today.  I ran out of heat stop 50, so I bought two bags of Sakrete high temp mortar. I only save $10 a bag though, so I wonder if its worth changing.  I believe they are probably similar though and probably won't matter.

[Pod4477]

So I got the whole first course done and the front, over the doorway done.  I mortared the angle iron down and mortared bricks on the angle iron.  So for the sides, since the angle iron is so thick in the front row, I had ¾" joints to get the sides level height.  I had a brick with ¾" joint mortared, but ended up removing that one brick, just now.  This does make sense since there are two joint heights and steel thickness, ¼+¼+¼.  So do you guys think ¾" will be okay for the second course walls?  But, this will also be the case for the back row, so I think I'm just going to use angle irons on the 3 other walls, to match the front one.  That way the joints are only ¼" thick max.  I need to get two more ¼" angle irons tomorrow, along with more for the ceiling. 

[Jon in Albany]

So I got the whole first course done and the front, over the doorway done.  I mortared the angle iron down and mortared bricks on the angle iron.  So for the sides, since the angle iron is so thick in the front row, I had ¾" joints to get the sides level height.  I had a brick with ¾" joint mortared, but ended up removing that one brick, just now.  This does make sense since there are two joint heights and steel thickness, ¼+¼+¼.  So do you guys think ¾" will be okay for the second course walls?  But, this will also be the case for the back row, so I think I'm just going to use angle irons on the 3 other walls, to match the front one.  That way the joints are only ¼" thick max.  I need to get two more ¼" angle irons tomorrow, along with more for the ceiling.

I'm not 100% clear on the question. IIRC, Heatstop is good for up to 1/2 inch joints. I'd avoid a large 3/4 mortar seam.

I think you are stacking the bricks vertically, soldier course, in your photo above. Would you be able to go stretcher courses on top? If I'm visualizing it right, not necessarily case - I usually draw it out, but i think 3 stretcher courses gets you 9 inches of brick plus mortar joints. You would be able to spread the 3/4 inch difference over a few joints. Might help you work out getting level. No idea what that means to a brick count or amount of mortar needed. Also, good brick laying practice is to make it so the mortar seams dont line up and you get a running bond.

No experience with sakrete here.

[Pod4477]

I'm not 100% clear on the question. IIRC, Heatstop is good for up to 1/2 inch joints. I'd avoid a large 3/4 mortar seam.

I think you are stacking the bricks vertically, soldier course, in your photo above. Would you be able to go stretcher courses on top? If I'm visualizing it right, not necessarily case - I usually draw it out, but i think 3 stretcher courses gets you 9 inches of brick plus mortar joints. You would be able to spread the 3/4 inch difference over a few joints. Might help you work out getting level. No idea what that means to a brick count or amount of mortar needed. Also, good brick laying practice is to make it so the mortar seams dont line up and you get a running bond.

No experience with sakrete here.

Thank you for the info!  Sorry was working on the oven all day yesterday and didn't get on here.  So I finished the entire first and second course.  I mortared the bricks in stretcher orientation for the second course.  I've made sure to have a max of ½" joints.  I used steel flats on the sides, as they didn't have angle irons in ¼" thickness at metal supermarkets yesterday.  I ended up getting 14 ¼" angle irons for the ceiling.  I figured having ¼" instead of ⅛" would be stronger. 

As you can see, I mortared the heck out of the outside of the bricks.  The first heat stop 50 bag didn't have the better sticky consistency of the second bag I bought, so I just wanted to make sure nothing would move in the future.  The front left corner isn't exactly level, by about ¼"-½" but I'm sure when I mortar the ceiling angle irons, I will make up for that.  I'm curious if I should mortar in the bricks on the ceiling angle irons though.  Obviously I'll mortar the angle irons to the walls, but I don't want mortar flaking down into food.  My thought is that the ceiling bricks shouldn't move if I have concrete over the entire ceiling later on.  What do you guys think? In reply #26, it does look like mortar was used in the ceiling angle irons, but not sure.  The side walls look unlevel, but it’s just the picture. They’re pretty level in person.

The second and third pic show gaps on the side and back when laying the ceiling angle irons dry. I’m assuming I’d want to fill all these gaps with mortar?

[Jon in Albany]

Thank you for the info!  Sorry was working on the oven all day yesterday and didn't get on here.  So I finished the entire first and second course.  I mortared the bricks in stretcher orientation for the second course.  I've made sure to have a max of ½" joints.  I used steel flats on the sides, as they didn't have angle irons in ¼" thickness at metal supermarkets yesterday.  I ended up getting 14 ¼" angle irons for the ceiling.  I figured having ¼" instead of ⅛" would be stronger. 

As you can see, I mortared the heck out of the outside of the bricks.  The first heat stop 50 bag didn't have the better sticky consistency of the second bag I bought, so I just wanted to make sure nothing would move in the future.  The front left corner isn't exactly level, by about ¼"-½" but I'm sure when I mortar the ceiling angle irons, I will make up for that.  I'm curious if I should mortar in the bricks on the ceiling angle irons though.  Obviously I'll mortar the angle irons to the walls, but I don't want mortar flaking down into food.  My thought is that the ceiling bricks shouldn't move if I have concrete over the entire ceiling later on.  What do you guys think? In reply #26, it does look like mortar was used in the ceiling angle irons, but not sure.  The side walls look unlevel, but it’s just the picture. They’re pretty level in person.

The second and third pic show gaps on the side and back when laying the ceiling angle irons dry. I’m assuming I’d want to fill all these gaps with mortar?

Thank you for the info!  Sorry was working on the oven all day yesterday and didn't get on here.  So I finished the entire first and second course.  I mortared the bricks in stretcher orientation for the second course.  I've made sure to have a max of ½" joints.  I used steel flats on the sides, as they didn't have angle irons in ¼" thickness at metal supermarkets yesterday.  I ended up getting 14 ¼" angle irons for the ceiling.  I figured having ¼" instead of ⅛" would be stronger. 

As you can see, I mortared the heck out of the outside of the bricks.  The first heat stop 50 bag didn't have the better sticky consistency of the second bag I bought, so I just wanted to make sure nothing would move in the future.  The front left corner isn't exactly level, by about ¼"-½" but I'm sure when I mortar the ceiling angle irons, I will make up for that.  I'm curious if I should mortar in the bricks on the ceiling angle irons though.  Obviously I'll mortar the angle irons to the walls, but I don't want mortar flaking down into food.  My thought is that the ceiling bricks shouldn't move if I have concrete over the entire ceiling later on.  What do you guys think? In reply #26, it does look like mortar was used in the ceiling angle irons, but not sure.  The side walls look unlevel, but it’s just the picture. They’re pretty level in person.

The second and third pic show gaps on the side and back when laying the ceiling angle irons dry. I’m assuming I’d want to fill all these gaps with mortar?

Broken record: no experience with this style of oven but my 2 cents anyway...

I dont think you need to mortar the ceiling brick together if they are snug and you cast over them. I dont think putting mortar in the ceiling would hurt anything either.

I think the gaps between the wall and ceiling should get closed somehow. Heat and smoke will get out through those gaps. Filling with mortar is probably the easiest and most structurally sound solution. It creates a nice, solid full length bearing area for the angle.

[Pod4477]

Broken record: no experience with this style of oven but my 2 cents anyway...

I dont think you need to mortar the ceiling brick together if they are snug and you cast over them. I dont think putting mortar in the ceiling would hurt anything either.

I think the gaps between the wall and ceiling should get closed somehow. Heat and smoke will get out through those gaps. Filling with mortar is probably the easiest and most structurally sound solution. It creates a nice, solid full length bearing area for the angle.

Your input is much appreciated. That was my thought too about the ceiling, so I’m happy you confirmed what I was thinking. I’ll just make sure to plug any small gaps with mortar. I’m hoping to finish it all tomorrow. I bought a flat steel piece to fill the front gap that was left from not leveling right. The gap is more than ½” so I figure probably better to mortar some steel in there instead of a large mortar joint.

So the oven should sit for a week to dry and then 2 weeks of fire curing, but after I finish the oven tomorrow, does the 1 week drying include the concrete I may use on the outside, possibly over a blanket?  I’m just wondering if that needs to dry for a week also, before firing.  My other idea is to fire it up without a chimney, to see how the wide door opening works, before building the chimney vent and chimney. I should be able to make the opening smaller if need be. Is this a good idea?

[Jon in Albany]

Curing is a misleading word. Yes concrete and mortar gain strength with age. Concrete can kind of slowly gain strength for decades. In my opinion, what the small and slowly increasing fires do is drive out excess water. You cant get up to 600-700 with extra water there. It will boil off first. Getting the water (in the form of steam) out too fast can cause big cracks. Personally, I would start the fires once everything was done but I dont think it is 100% necessary to wait. I started slow on my oven with no insulation blanket on it. I tried to keep the temps in the 100s then low 200s. I could see steam come off. Could also hear the occasional hiss. After a several small uninsulated fires, I added the blankets and increased temps over more fires. I'd like to brag and say I have a crack-less oven, but that would be a lie.

One other thought to consider about firing without a chimney...the little fires can smoke quite a bit so there will be soot on the front. Not sure if that will require cleaning before your chimney or door construction.

[foreplease]

You are beyond anything I know how to help with now but the photos are quite helpful in helping me understand what you are doing.


Did you see that Hans ate at your beloved Pizzeria Regina on the North End tonight? He does a good job reviewing the many places he visits.
https://www.pizzamaking.com/forum/index.php?topic=57885.0

[Pod4477]

Curing is a misleading word. Yes concrete and mortar gain strength with age. Concrete can kind of slowly gain strength for decades. In my opinion, what the small and slowly increasing fires do is drive out excess water. You cant get up to 600-700 with extra water there. It will boil off first. Getting the water (in the form of steam) out too fast can cause big cracks. Personally, I would start the fires once everything was done but I dont think it is 100% necessary to wait. I started slow on my oven with no insulation blanket on it. I tried to keep the temps in the 100s then low 200s. I could see steam come off. Could also hear the occasional hiss. After a several small uninsulated fires, I added the blankets and increased temps over more fires. I'd like to brag and say I have a crack-less oven, but that would be a lie.

One other thought to consider about firing without a chimney...the little fires can smoke quite a bit so there will be soot on the front. Not sure if that will require cleaning before your chimney or door construction.

Thank you!  That was a very helpful writeup and good to know about curing.  So did you concrete over your blanket?  I bet your oven still has few cracks.  That's a good point about soot.  Maybe I can dry stack some old bricks in place to cover up the area for the chimney.  Do I have to wait a week for the mortar to dry, before I do the small fires?

I got the oven fully done yesterday, besides the chimney.  I'll post pics from my phone.  I still need to cover with a blanket and concrete, but I plugged all gaps with heat stop.

You are beyond anything I know how to help with now but the photos are quite helpful in helping me understand what you are doing.


Did you see that Hans ate at your beloved Pizzeria Regina on the North End tonight? He does a good job reviewing the many places he visits.
https://www.pizzamaking.com/forum/index.php?topic=57885.0

Sorry I'll post more pics for sure.  Oh wow I didn't notice that!  I like the review and I agree with it.  The sauce is very important.  Tomato Magic was the closest I've had.

[Pod4477]

Also, just noticed that the front angle iron is not flush with the front bricks by about ½".  Obviously this won't matter much with a wood door as it will have a gasket, but I just worry about having a metal door flush as far as keeping out mice.  I'm going to build the chimney tomorrow, but I think by mortaring over the front angle iron, I can make everything flush.  Does this seem sound?  I'm going to have to mortar bricks to the front angle iron or above it, anyway.  My other idea is that since I'd only use the metal door for storage uses and not during firing, maybe I can have a gasket installed onto a steel door to make up for any gaps.  I know mice can fit through a dime size, so it's nearly impossible to keep them out.

[Jon in Albany]

I thought you were connecting the door to the angle. If you mortar over the angle, I think you lose that option. I don't know how every thing fits together. Any chance you could connect build up the angle section bu connecting a piece of flat stock steel?

I dont recall you mentioning a wood door. Wouldn't a wood door slowly smolder or burn?