Wanting to build a coal fired style outdoor pizza oven

[Pod4477]

I didn’t follow that entirely but it sounds as if you have the details for next part figured out. One suggestion: if you splice rebar, alternate sides so all, the short pieces are not along the same wall.


Maybe when this thing is done and working you or someone could teach me how multi-quote works (please). I have not been able to figure it out in 3+ years here

I think I may have taken a pic of it.  Basically just made a center column of block in the middle for the wood to be supported by.  Good tip for the rebar, thank you!  It's important to overlap them a lot before tying them together right?
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.

[foreplease]

It’s good to see some pictures! Looks as though it will turn out as you hoped but you have more decisions ahead. Yes, I would think it is important to overlap the rebar a lot. I don’t remember how long your pieces are compared to the span but I would probably just not cut any of them and let them overlap as much as that allows. You are bending them 90° and inserting one end into the top block (at least) of your walls, right? Lay them out on alternating sides and tie them together as planned. Please keep posting pics - it makes things so much more clear. As I said another time, I know nothing about ovens but a fair amount about building things to last.


Thanks for the multi-quote advice. I will find a quiet thread to try it out sometime.

[Jon in Albany]

The plywood looks like it came our great. Glad that everything fit.

I haven't looked at anything rebar code-wise in a long time. Longer lap length is better and like Tony suggested alternating sides is the way to go.

[Pod4477]

Thanks, Jon. Good to know. Although I have not been too involved here I am finding it difficult to walk away. I keep hoping to see this thing come together for brother Pod.


I hope you were being funny with your ‘screwed up’ and ‘I suck’ comments. I meant nothing like that at all.

Also, meant to say thank you.  I'm hoping it comes together as I plan.  So far the only weird thing is some of the block sticking out a bit (maybe ¼" on two courses) in the back, which I attribute to not getting every block 100% plumb or just imperfections.  I made sure to get the stand quite plumb though before making it permanent, as all sides are 62.5 away from the other side.  The first course was very good, so my other guess is it's just from staggering the block and any size differences.  The stand is solid though and quite straight sides, so any imperfections should be covered up by brick eventually if I do a veneer.  I suppose I could always sand the edges of the block, but I think I'll probably just bring the brick veneer out ¼" more on the back, where some of the blocks stick out that ¼".

It’s good to see some pictures! Looks as though it will turn out as you hoped but you have more decisions ahead. Yes, I would think it is important to overlap the rebar a lot. I don’t remember how long your pieces are compared to the span but I would probably just not cut any of them and let them overlap as much as that allows. You are bending them 90° and inserting one end into the top block (at least) of your walls, right? Lay them out on alternating sides and tie them together as planned. Please keep posting pics - it makes things so much more clear. As I said another time, I know nothing about ovens but a fair amount about building things to last.


Thanks for the multi-quote advice. I will find a quiet thread to try it out sometime.

Sorry I haven't posted many pics but that will change I was wondering if I should bend them into the walls.  I've seen both ways, while Forno Bravo doesn't do it in their instructions.  Makes sense though to tie it in with the stand.  With the length being short by a foot, the only way I can do that is to splice some rebar in and bend it.  You definitely know a lot! 

The 4' rebar is what I got at Lowes, without having to buy the big 12 footers.  I maybe should have, but I didn't want to cut any.  And Np!  I use it a lot as you can tell.  hahaha the quite thread part made me lol, literally.

The plywood looks like it came our great. Glad that everything fit.

I haven't looked at anything rebar code-wise in a long time. Longer lap length is better and like Tony suggested alternating sides is the way to go.

Thanks!  You know a ton as well and it has really helped, as well as from all you guys.  Idk why I didn't think of making it 48x55" at first.  When I read 48x55" from your other post, I read it as 48-55", I don't know why.  So you basically just lap them and then tie them really tight with the same rebar ties that I'll use for the intersections?  I also need to decide on which orientation the oven will face.  I'm assuming I take a flame outside and see which way the wind blows on average, and then face the opening away from that?

[Jon in Albany]

Also, meant to say thank you.  I'm hoping it comes together as I plan.  So far the only weird thing is some of the block sticking out a bit (maybe ¼" on two courses) in the back, which I attribute to not getting every block 100% plumb or just imperfections.  I made sure to get the stand quite plumb though before making it permanent, as all sides are 62.5 away from the other side.  The first course was very good, so my other guess is it's just from staggering the block and any size differences.  The stand is solid though and quite straight sides, so any imperfections should be covered up by brick eventually if I do a veneer.  I suppose I could always sand the edges of the block, but I think I'll probably just bring the brick veneer out ¼" more on the back, where some of the blocks stick out that ¼".

Sorry I haven't posted many pics but that will change I was wondering if I should bend them into the walls.  I've seen both ways, while Forno Bravo doesn't do it in their instructions.  Makes sense though to tie it in with the stand.  With the length being short by a foot, the only way I can do that is to splice some rebar in and bend it.  You definitely know a lot! 

The 4' rebar is what I got at Lowes, without having to buy the big 12 footers.  I maybe should have, but I didn't want to cut any.  And Np!  I use it a lot as you can tell.  hahaha the quite thread part made me lol, literally.
Thanks!  You know a ton as well and it has really helped, as well as from all you guys.  Idk why I didn't think of making it 48x55" at first.  When I read 48x55" from your other post, I read it as 48-55", I don't know why.  So you basically just lap them and then tie them really tight with the same rebar ties that I'll use for the intersections?  I also need to decide on which orientation the oven will face.  I'm assuming I take a flame outside and see which way the wind blows on average, and then face the opening away from that?

Yes, you just tie the bars together. It may have changed but I think the code used to be 40 bar diameters. So for half inch bar it would be 20 inches for a full lap length. Running the bar into the top course will make the stand stronger.

For wind, I found what is called a wind rose online. It is an analysis of like a years worth of wind data. In my area, it is mostly in two directions. You can also look at the orientation of the airports runways. Maybe one of the pilots members can confirm this, but I thought planes took off into the wind. Whoever planned the runways will have looked at wind data. Anyhow, if you can find a wind rose online for your area you will know for sure. I'd hate to have you check the wind on an off day and build based on that data.

[Pod4477]

Yes, you just tie the bars together. It may have changed but I think the code used to be 40 bar diameters. So for half inch bar it would be 20 inches for a full lap length. Running the bar into the top course will make the stand stronger.

For wind, I found what is called a wind rose online. It is an analysis of like a years worth of wind data. In my area, it is mostly in two directions. You can also look at the orientation of the airports runways. Maybe one of the pilots members can confirm this, but I thought planes took off into the wind. Whoever planned the runways will have looked at wind data. Anyhow, if you can find a wind rose online for your area you will know for sure. I'd hate to have you check the wind on an off day and build based on that data.

Thanks so much.  So is that 20" length of overlap basically?   
That is a much better way to do it than have an off day mess it up.  So it looks like since 1946, the wind usually blows from South-North West.  Most of the wind comes from SSW, but a lot does come from West-North West.  This is awesome news and confirms what I've been feeling when building the stand.  I had a feeling the opening would have to around North East - East.  Thank you!

Also, I set up the wood framing as a test run.  I do think I'll just place it on the stand, because the stand's edges won't work with the wood.  So is it best to just use wood screws and I wasn't sure how long they usually should be.  I estimated 3-4" screws. I also wonder if corner braces and strapping are needed. The model for the framework should look like this: http://thewoodfiredenthusiast.com/building-my-wood-fired-oven-construction-walk-through-pt1-foundation-stand/

I'm going to start pouring the support concrete Saturday morning and then should I leave the forms on for 24 hours, then pour the insulating layer, and then wait 24 hours for that to cure before popping them off?  I'm a bit nervous about leaving the forms on too long, so where I'm using the same form and planning on keeping it there until the insulating layer is screeded, what is the max time it should stay on for?

[foreplease]

Pod,
The corner braces and strap as shown in the pictures from your link are a smart idea. The braces across the top of the corners would be easy. You could do it with scraps and wouldn’t even have to measure or cut anything if you don’t want to bother. The strap would buy you another little piece of mind but you can probably get by without it. Just make sure the frame is solidly joined and you brace the top. I have poured small things like stanchions for pitching mounds and bases on ball fields and always cinched and tied a rope around my forms just to be safe. That’s only my opinion and guess.


The lumber forms will come off. If you want to make it easier take an old paint brush and some oil and cover the edges of the lumber that will come in contact with the concrete. It’s like greasing a pan before you make brownies. 

[Jon in Albany]

I agree with Tony. Just to elaborate on the oil, vegetable oil would work. I skipped it because I was going to try and keep using the wood. (My upper slab 2x8 boards are currently supporting some firewood) My slab edges didn't come out the prettiest but I figured they would eventually be covered up. Should have paid more attention to them during the pour than I did.

Yes, that 20 inch lap length is just the length of the splice usually tied together with some wire. The wire is only keeping everything in place during the pour, no strength gain from the wire.

One thing I wanted to point out from ths link is the shims in places to make the top of the form level. Level is nice here, but you still get a chance for a correction in the perlcrete layer. I'd give your concrete layer 24 hours to cure. You could probably get away with less time at our current outdoor temperatures. With your plan, you could leave the form on while you se up the perlcrete form. That won't hurt anything. Put plastic over the concrete to keep the water from evaporating while the concrete cures.

That site was set up by member StoneCutter. He has built some very pretty stuff.

For wood screws, I used 3 inch deck screws I had. Pilot holes are a good idea so you don't split the boards.

[Pod4477]

Pod,
The corner braces and strap as shown in the pictures from your link are a smart idea. The braces across the top of the corners would be easy. You could do it with scraps and wouldn’t even have to measure or cut anything if you don’t want to bother. The strap would buy you another little piece of mind but you can probably get by without it. Just make sure the frame is solidly joined and you brace the top. I have poured small things like stanchions for pitching mounds and bases on ball fields and always cinched and tied a rope around my forms just to be safe. That’s only my opinion and guess.


The lumber forms will come off. If you want to make it easier take an old paint brush and some oil and cover the edges of the lumber that will come in contact with the concrete. It’s like greasing a pan before you make brownies. 

Thank you.  I think I'll do corner braces for the structural concrete layer and then maybe take them off to screed the perlcrete layer perfectly.  That's really cool, I love baseball, and from what I've read on here and other sites, it's always good to tie or strap the the boards for sure.  I have been getting good at buttering cake pans lately, so I will brush it with some oil.  I was just about to ask how most people coat the boards; a brush makes a lot of sense.

I agree with Tony. Just to elaborate on the oil, vegetable oil would work. I skipped it because I was going to try and keep using the wood. (My upper slab 2x8 boards are currently supporting some firewood) My slab edges didn't come out the prettiest but I figured they would eventually be covered up. Should have paid more attention to them during the pour than I did.

Yes, that 20 inch lap length is just the length of the splice usually tied together with some wire. The wire is only keeping everything in place during the pour, no strength gain from the wire.

One thing I wanted to point out from ths link is the shims in places to make the top of the form level. Level is nice here, but you still get a chance for a correction in the perlcrete layer. I'd give your concrete layer 24 hours to cure. You could probably get away with less time at our current outdoor temperatures. With your plan, you could leave the form on while you se up the perlcrete form. That won't hurt anything. Put plastic over the concrete to keep the water from evaporating while the concrete cures.

That site was set up by member StoneCutter. He has built some very pretty stuff.

For wood screws, I used 3 inch deck screws I had. Pilot holes are a good idea so you don't split the boards.

1.  I was just going to ask what oil is okay to use, so thank you!  I will definitely oil them down a lot.  Yeah, it doesn't seem really crucial to get it looking amazing when it will be covered anyway.  As long as it's structural and level I'm happy.  I'll make sure to make it 20" lap length if I do splice them in.  It will be my first time making a rebar grid.  I'm thinking of just leaving the forms up, but would a tarp over the framework be good to keep the concrete from drying out, or is it best to lay a cut piece of plastic over the concrete when it's semi cured?
Oh I didn't know it was from a member.  His and all your ovens look amazing.  I may do a full brick veneer over the block stand and oven. 

2.  I have some 2 ½" exterior screws that could work, but I think 3" would be a safer bet.  So true about pilot holes, I've learned my lessons not drilling them in the past.

3.  Also, my plan is to pour concrete over the firebrick and make a sloped shape to it from front to back sloping down, very much like https://www.flickr.com/photos/climbhipa/3272605452/in/album-72157613634415857/, but I wonder the best way to install roofing onto concrete.

4.  Lastly, I forgot that I'm going to put up a tall fence around the area, so I'm assuming that would cut out most wind as long as the fence is taller than the oven?

[Jon in Albany]

1. I think a tarp would work. The idea is to keep the sun from evaporating all the water off the top. Based on the weather in the northeast for the past few weeks, it might not be s big deal. But keeping the water in there will help the concrete cure.

3. Looks like they hand troweled a mix with pea stone for aggregate. Not really sure though.

4. I think it would depend on how far the oven is from the fence and what else is around you. My guess, and it is just a guess, is that if everything is open and relatively flat, the wind would go over the fence kind of like fast flowing water over a dam. Again, just a guess.

[Pod4477]

1. I think a tarp would work. The idea is to keep the sun from evaporating all the water off the top. Based on the weather in the northeast for the past few weeks, it might not be s big deal. But keeping the water in there will help the concrete cure.

3. Looks like they hand troweled a mix with pea stone for aggregate. Not really sure though.

4. I think it would depend on how far the oven is from the fence and what else is around you. My guess, and it is just a guess, is that if everything is open and relatively flat, the wind would go over the fence kind of like fast flowing water over a dam. Again, just a guess.

Thank you for the fast and thorough reply.  A lot of the info I'm using immediately, so I really appreciate the help and the speed of it has been amazing.

1.  The sun worked opposite wonders on my mortar I was mixing last week, so I witnessed how quick it can dry in the hot sun.  I bought a new tarp so I could try that.  Yup so much rain, I haven't even been able to pour this slab for a week.

3.  Thank you; there were no other comment on their pics of that process besides them mentioning concrete.  It seems like they put in some wire mesh and covered that with the mix, and then used wood framing to keep it in a box shape.  Then they built up the brick facade/walls along with a stone front piece, and then built the roof into the gap between the walls and oven ceiling.  Pretty cool idea and since I may build a brick facade over the entire stand, maybe I can do something similar.  I definitely need something to cover the concrete shell; I could build a structure, but I like the look of a roof on the oven.

4.  Ya lots of variables definitely.  Where I have the door facing in my head would be facing SE, and the majority of the wind comes from South to North West.  It seems that without any fence, most winds from SSW-WNW should be blocked by the house.  Any wind from South that goes around the house should roll over the fence.  Any winds from NW should hit the side of the oven and not the opening.  That's how it seems, but might not be correct.  I'll get some measurements of the area, but there should be about 5-6 feet clearance around the non flammable  fence.

[Pod4477]

Got the framing set up and now just have to pour the concrete tomorrow morning    Got 8 bags already, and need to get 10 more bags of concrete when I wake up.

[Pod4477]

Got the supporting concrete layer done and covered with a tarp!  Now have to do the perlcrete tomorrow.  Everything went as planned and I'll post pics from my phone in a bit; left my phone in the car.  It may rain tomorrow night, so I should probably put the perlcrete layer on in the morning.

[Pod4477]

annnnnd finished the perlcrete layer today.  I hope I got the consistency right for it.  It wasn't too wet, but also wasn't dry so I think it matched the look of the videos I've seen with it.  Thunderstorm coming in as I type, so I have it covered with a tarp.  I'm assuming if water gets in that would be pretty bad?  I have it covered with two tarps just incase of any holes.  When should   I take the forms off?  I'm thinking the perlcrete should cure for at least 24 hours before taking them off?  I hope the pearlcrete doesn't stick to the forms, as I forgot to oil the extra wood trim I added to get the perlcrete a bit higher. 

I’m also deciding if I use fireclay and sand for leveling. Is there a reason people don’t use just dry sand like for pavers?  My best guess was because the wet fireclay and sand lock the bricks in place better than sand.

[Jon in Albany]

I dont think a little extra water trickling onto the perlcrete will hurt it but it will just take longer to dry out.

Hopefully the layer is level enough to not really need any sand. The main reasons I used fireclay was to make a softer pad for board insulation then leveling different materials (I split my oven floor into 2 sections). Ideally you can put the firebrick right on top of the perlcrete.

I left the perlcrete forms on for a few days. It kind of went through stages- obviously still wet, crumbly (hope it gets firmer than this), looks firmer (took the form off, and finally wow, that's actually pretty solid.

I think if you hit each side of your form a few times with a hammer before unscrewing it, this sides will come off easy. The sides on mine came off easy, it was the large pieces of plywood underneath that stuck.

[Pod4477]

I dont think a little extra water trickling onto the perlcrete will hurt it but it will just take longer to dry out.

Hopefully the layer is level enough to not really need any sand. The main reasons I used fireclay was to make a softer pad for board insulation then leveling different materials (I split my oven floor into 2 sections). Ideally you can put the firebrick right on top of the perlcrete.

I left the perlcrete forms on for a few days. It kind of went through stages- obviously still wet, crumbly (hope it gets firmer than this), looks firmer (took the form off, and finally wow, that's actually pretty solid.

I think if you hit each side of your form a few times with a hammer before unscrewing it, this sides will come off easy. The sides on mine came off easy, it was the large pieces of plywood underneath that stuck.

thank you!  That was a good idea for using the fireclay and hopefully I won't even need it.  Can I use clay dug up from the ground?  The two section thing is awesome and I would have done that if I had definite dimensions. I think I have it all figured out, but I'll dry stack soon.

Going to check it tonight.  It seemed crumbly and solid when I checked it last night.  I'll definitely tap them when I take them off tomorrow.  The plywood underneath always seemed like it would be stuck, so it's fun to just leave it in my case.

[Jon in Albany]

thank you!  That was a good idea for using the fireclay and hopefully I won't even need it.  Can I use clay dug up from the ground?  The two section thing is awesome and I would have done that if I had definite dimensions. I think I have it all figured out, but I'll dry stack soon.

Going to check it tonight.  It seemed crumbly and solid when I checked it last night.  I'll definitely tap them when I take them off tomorrow.  The plywood underneath always seemed like it would be stuck, so it's fun to just leave it in my case.

I honestly don't know how well local clay just dug up would work. Maybe if you dried it and broke it into particles. No idea.

I believe there are some ovens that have a salt layer to them. I never really looked into using salt though.  For your purposes, I think you will be fine in top of the perlcrete. Have you put a level on it to see how it came out?

[foreplease]

I have used several thousand of these unfired clay blocks to build pitcher’s mounds and durable batter’s boxes (3 layers thick for both).
https://www.turface.com/products/mound-box-packing-clays/moundmaster-blocks


I used to buy bagged crumbled clay to topdress and level with but didn’t really like working with it.
https://www.turface.com/products/mound-box-packing-clays/mound-clay


So, since I always have the blocks on hand, I began softening them in a 5 gal pail of water for 2 days, pour off the water, then used a 1/2” drill motor and drywall mud paddle to whip them into a soupy paste (6-8 blocks per bucket of water). Then I would trowel it on with a big drywall finishing knife. Worked great. Much less bumpy than the bagged clay, which had to be beaten to within an inch of its life with a heavy tamp. It wasn’t really important that it be perfectly smooth as the top layer of 3/8-1/2” infield dirt takes care of that. I skim coated everything to prevent infield dirt settling between the blocks before time, weather, and pressure could fuse them together.

[Pod4477]

I honestly don't know how well local clay just dug up would work. Maybe if you dried it and broke it into particles. No idea.

I believe there are some ovens that have a salt layer to them. I never really looked into using salt though.  For your purposes, I think you will be fine in top of the perlcrete. Have you put a level on it to see how it came out?

Sorry been working on the stand all day.  Ya not sure, probably not as good.  Salt is interesting! I didn't know that. The perlcrete layer is pretty level!  I took the forms off and didn't realize that by having the wood boards indented on the blocks, some of the unfilled cores may not get fully covered with concrete.  I should maybe have filled every core.  The boards were so thick that they crept up a bit over the cores, by about ¼".  I filled in any openings today with concrete; not the prettiest and might not stop water.  I'm just worried about water getting in there, but it's pretty closed now. 

There were quite a lot of air holes or bugholes from not tapping the boards, but the concrete is strong anyway.  The perlcrete has hardened; but the top has some loose concrete colored perlite that can slide around, as well as the corners seem very fragile.  My assumption is just from the top and corners drying more and just normal loose perlite.  Most has hardened though.  Can I stucco over the corners just to keep them from getting broken off?  Won't matter much as the oven doesn't even come to the edges.  I'll have to see how I protect/facade around these exposed layers and the oven, either by building a structure or doing a brick facade over it all.

I have used several thousand of these unfired clay blocks to build pitcher’s mounds and durable batter’s boxes (3 layers thick for both).
https://www.turface.com/products/mound-box-packing-clays/moundmaster-blocks


I used to buy bagged crumbled clay to topdress and level with but didn’t really like working with it.
https://www.turface.com/products/mound-box-packing-clays/mound-clay


So, since I always have the blocks on hand, I began softening them in a 5 gal pail of water for 2 days, pour off the water, then used a 1/2” drill motor and drywall mud paddle to whip them into a soupy paste (6-8 blocks per bucket of water). Then I would trowel it on with a big drywall finishing knife. Worked great. Much less bumpy than the bagged clay, which had to be beaten to within an inch of its life with a heavy tamp. It wasn’t really important that it be perfectly smooth as the top layer of 3/8-1/2” infield dirt takes care of that. I skim coated everything to prevent infield dirt settling between the blocks before time, weather, and pressure could fuse them together.

Thank you; very cool!  I enjoyed reading about your process.  So I may be best by buying the blocks and then processing them myself?  That's pretty close to what one site mentioned about how to use already formed clay and breaking it into bits.

[foreplease]

I think you could use bagged clay or blocks if you plan to soften them in water as I described. If you have a “SiteOne” store near you they may stock it. They used to be called LESCO, then John Deere Landscapes, now SiteOne.
Here are a couple pics of how I used them and one of the skim coat I described.