A D V E R T I S E M E N T


Author Topic: Wanting to build a coal fired style outdoor pizza oven  (Read 11264 times)

0 Members and 1 Guest are viewing this topic.

Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #140 on: May 13, 2019, 05:52:08 PM »
I guess I'm using the sand in place of the wood supports and pouring the concrete slabs right over it.  The only thing is that if I don't fill the sand right to the top of the block, the first support slab would have an odd shape from going down a bit into the sand and then up on top of the block.  The stand is 30.75" tall and that is even shorter than the 2 tons of sand I calculated (31" calculation), so my plan will probably be to fill the stand entirely with sand up to the top of the block, and then just pour 3-4" rebar concrete support over the sand and the block, followed by 3-4" perlcrete, using a wooden frame.  Out of breath there a bit.

I'm assuming being in the middle is best consistency for the support concrete?  The insulating layer usually suggests adding enough water for the perlite to clump up.

You still don't need to worry about how flat the bottom of the slab is. Make the top level. Whatever minimum thickness you want the slab to be, make sure the slab is at least that thick everywhere. So if you want a 4 inch slab, and parts are 4.25 and one spot is 4.5 and another is 4.1...it doesn't matter as long as the top is flat. You would just be using a little more concrete. I'd throw a piece of plastic sheeting over the sand so that it doesn't wick and water from the mix. It will also prevent any water from coming up from the sand once you are done.

30.7.5 + 4 (concrete) + 4 (perlcrete) + 2.5 (floor brick) + 9 (top of door) = 50.25

I recommend cutting up some cardboard to make something that shows you where your oven floor is (41.25) and blocks off anything above 50.25 in which will be your line of sight. I believe you will be bent over to see in the oven. For reference, my oven floor is at about 50 and a bit higher would have been fine. Rule of thumb is about elbow height for the oven floor.

A little extra water in the concrete mix will not hurt anything. It is when you add a bunch of water and the paste gets really thin and the stone starts to separate that creates some problems.


Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #141 on: May 13, 2019, 07:07:08 PM »
You still don't need to worry about how flat the bottom of the slab is. Make the top level. Whatever minimum thickness you want the slab to be, make sure the slab is at least that thick everywhere. So if you want a 4 inch slab, and parts are 4.25 and one spot is 4.5 and another is 4.1...it doesn't matter as long as the top is flat. You would just be using a little more concrete. I'd throw a piece of plastic sheeting over the sand so that it doesn't wick and water from the mix. It will also prevent any water from coming up from the sand once you are done.

30.7.5 + 4 (concrete) + 4 (perlcrete) + 2.5 (floor brick) + 9 (top of door) = 50.25

I recommend cutting up some cardboard to make something that shows you where your oven floor is (41.25) and blocks off anything above 50.25 in which will be your line of sight. I believe you will be bent over to see in the oven. For reference, my oven floor is at about 50 and a bit higher would have been fine. Rule of thumb is about elbow height for the oven floor.

A little extra water in the concrete mix will not hurt anything. It is when you add a bunch of water and the paste gets really thin and the stone starts to separate that creates some problems.

Thank you for all that info!  Huge help honestly.  So then it doesn't matter if the sand is flush with the top of the block, which makes it easier.  Plastic sheet is a great idea and so is the cardboard.  I'll do that.  I'm pretty short, 5'4", but anything under 40 seemed too low and yeah 45 might be better.  41" did seem pretty good though.  Thank you, I was worried about the water, but I'm fine then.  That is the appearance of when I add initial water on top of the concrete mix and the stone separates.  Looks pretty crazy until it's mixed in. 

Also, talked to another supply shop and they can do it all for around $90 in 2 days.  Tomorrow is supposed to be pretty bad out so I'd do it Wednesday if I decide to.  So I'm assuming concrete sand is what I should go with over brick sand?  It's a bit cheaper.

Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #142 on: May 13, 2019, 08:26:22 PM »


Thank you for all that info!  Huge help honestly.  So then it doesn't matter if the sand is flush with the top of the block, which makes it easier.  Plastic sheet is a great idea and so is the cardboard.  I'll do that.  I'm pretty short, 5'4", but anything under 40 seemed too low and yeah 45 might be better.  41" did seem pretty good though.  Thank you, I was worried about the water, but I'm fine then.  That is the appearance of when I add initial water on top of the concrete mix and the stone separates.  Looks pretty crazy until it's mixed in. 

Also, talked to another supply shop and they can do it all for around $90 in 2 days.  Tomorrow is supposed to be pretty bad out so I'd do it Wednesday if I decide to.  So I'm assuming concrete sand is what I should go with over brick sand?  It's a bit cheaper.

Since you are talking numbers...

Your stand inside area is less than 4'x4', that's less than half a sheet of plywood. A 4x8 sheet of 23/32 plywood is about $30.

The concrete blocks are less than $2 each. Two stacked is 2x15.625=31.25 so you are right there. If you got 18 blocks (overkill), that's $36.

Stack 2 blocks the long way so they are the height of your walls in each corner, the middle of each wall and the center. Drop the plywood cut to size on top of the blocks. Done for under $70 without shoveling.

Or, another even cheaper idea is to get the plywood, cut it 48"x50" or so, have it supported by your stacked wall on all sides and add one or 2 block columns in the somewhere in the middle. 4 blocks and Lowes will do the plywood cut. You might be able to fit that in a car. Plywood could be tight fit in the car.

I apologize if I am confusing the issue, but if it were me, I'd really not want to shovel all that sand. It is hard enough mixing and placing the concrete without having just moved a truckload of sand.

If you go for sand, I think either of the sands you mentioned would be fine. If they are for use as building material, they should be free of sticks (and decomposing diapers).

I'll shut up and leave you alone now.

Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #143 on: May 13, 2019, 09:08:32 PM »

Since you are talking numbers...

Your stand inside area is less than 4'x4', that's less than half a sheet of plywood. A 4x8 sheet of 23/32 plywood is about $30.

The concrete blocks are less than $2 each. Two stacked is 2x15.625=31.25 so you are right there. If you got 18 blocks (overkill), that's $36.

Stack 2 blocks the long way so they are the height of your walls in each corner, the middle of each wall and the center. Drop the plywood cut to size on top of the blocks. Done for under $70 without shoveling.

Or, another even cheaper idea is to get the plywood, cut it 48"x50" or so, have it supported by your stacked wall on all sides and add one or 2 block columns in the somewhere in the middle. 4 blocks and Lowes will do the plywood cut. You might be able to fit that in a car. Plywood could be tight fit in the car.

I apologize if I am confusing the issue, but if it were me, I'd really not want to shovel all that sand. It is hard enough mixing and placing the concrete without having just moved a truckload of sand.

If you go for sand, I think either of the sands you mentioned would be fine. If they are for use as building material, they should be free of sticks (and decomposing diapers).

I'll shut up and leave you alone now.

haha no need to leave me alone and that is a ton (no pun intended) of shoveling and mixing.  I appreciate the help; those are both solid ideas.  Didn't even think of doing that and it eliminates any tamping or shoveling ;D.  I think I may just do one of those two ideas, and even rent a truck for 20 bucks if I have to.  My mustang doesn't fit much, but I could always borrow a family members car too.  So the first idea is to have the plywood fit only on the inside of the stand and the second idea is to have the plywood larger to cover some of the cores in the stand?  For the second option, I assume I'd need a 5'x5' sheet cut to around 55"x55"?  Tough to find 5x5 sheets, so I wonder if I could use two smaller sheets held up by the center blocks.
« Last Edit: May 13, 2019, 09:40:35 PM by Pod4477 »

Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #144 on: May 14, 2019, 09:10:48 PM »
Planning on trying to get some 5’x5’ plywood if I can, or put two pieces together. Also, does the rebar have to fill the entire top framing or can it be a little short on each side? I know 4’  rebar is common. I also have a bunch I could splice together.

A D V E R T I S E M E N T


Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #145 on: May 14, 2019, 10:40:01 PM »
Planning on trying to get some 5’x5’ plywood if I can, or put two pieces together. Also, does the rebar have to fill the entire top framing or can it be a little short on each side? I know 4’  rebar is common. I also have a bunch I could splice together.

Doesn't mean it isn't out there, but I have only seen 4x8 sheets of plywood or some portion of that cut up. I don't think you can find a 5 foot width of it.

If you could get the 10 foot pieces of bar, you could cut the length you need and then use the scraps in your cores. I got all my bar from a local shop of the Metal Supermarket chain. They sell by weight and cut to length. Not sure where you are but there is a Metal Supermarket in Woburn. I think you would be able to get 4 foot pieces to work but how much bar you put in there is up to you.

Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #146 on: May 14, 2019, 11:34:37 PM »
Doesn't mean it isn't out there, but I have only seen 4x8 sheets of plywood or some portion of that cut up. I don't think you can find a 5 foot width of it.

If you could get the 10 foot pieces of bar, you could cut the length you need and then use the scraps in your cores. I got all my bar from a local shop of the Metal Supermarket chain. They sell by weight and cut to length. Not sure where you are but there is a Metal Supermarket in Woburn. I think you would be able to get 4 foot pieces to work but how much bar you put in there is up to you.

Ya I haven't been able to find any 5'x5' despite Home Depot having an article mentioning it, but of course they only carry the 4x8.  Didn't know that about Woburn, thanks!  I would like not having to cut them, but will cut them if last resort.  I guess it would be a foot short on each side, but I was thinking it might be okay.  Most of the slab would have rebar throughout it.  So if I cut two 4x8 sheets of plywood into 2.5x5 sheets and then joined them, I assume that's the only way.  Would brackets be the best way to connect the two sheets?  I mean the block would be holding them up anyway, but I wonder the best way to approach that.  I want to do this all tomorrow, so I can have it covered with a tarp more securely.

Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #147 on: May 14, 2019, 11:46:08 PM »
Ya I haven't been able to find any 5'x5' despite Home Depot having an article mentioning it, but of course they only carry the 4x8.  Didn't know that about Woburn, thanks!  I would like not having to cut them, but will cut them if last resort.  I guess it would be a foot short on each side, but I was thinking it might be okay.  Most of the slab would have rebar throughout it.  So if I cut two 4x8 sheets of plywood into 2.5x5 sheets and then joined them, I assume that's the only way.  Would brackets be the best way to connect the two sheets?  I mean the block would be holding them up anyway, but I wonder the best way to approach that.  I want to do this all tomorrow, so I can have it covered with a tarp more securely.
I thought the inside dimensions of the stand were just under 47x47? I dont understand why you need 2, 5 foot pieces.

Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #148 on: May 15, 2019, 12:43:52 AM »
I thought the inside dimensions of the stand were just under 47x47? I dont understand why you need 2, 5 foot pieces.
Oh yup they are, but I'm thinking of laying the plywood over the entire stand (having it cover about halfway across the cores which came to about 55"x55") and supporting the middle with blocks.  That way I wouldn't have to use as many blocks in the middle area.  I interpreted your second idea as being that way and it's pretty smart.  I guess I'd only need 48"x48" though to have it lay across the stand, but I just wanted to make it larger to account for any shifting.
« Last Edit: May 15, 2019, 01:19:52 AM by Pod4477 »

Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #149 on: May 15, 2019, 06:58:23 AM »
Use the 48 as one side and as long as you'd like on the other. I think that will save you a lot of hassle and all the edges of the plywood will be supported.

A D V E R T I S E M E N T


Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #150 on: May 15, 2019, 09:45:23 AM »
I sketched this up to show what I meant. This is the stand with a shaded 48x55 piece of plywood. My gut feeling is 4 columns is overkill but the price difference between 2 and 4 columns is under $8.

Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #151 on: May 15, 2019, 10:32:20 AM »
I sketched this up to show what I meant. This is the stand with a shaded 48x55 piece of plywood. My gut feeling is 4 columns is overkill but the price difference between 2 and 4 columns is under $8.

Thank you!  I'm much more of a visual learner, so the sketches are much appreciated.  48x55 is a much better idea and yeah I don't mind the price difference, as I'll probably rent the truck anyway.  How set should the support layer be before I pour the insulating layer?

Also, talks about using a concrete vibrator or tapping the forms with a hammer to get the air pockets out and not to wait too long to tap the forms out. 
« Last Edit: May 15, 2019, 10:44:12 AM by Pod4477 »

Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #152 on: May 15, 2019, 10:41:27 AM »


Thank you!  I'm much more of a visual learner, so the sketches are much appreciated.  48x55 is a much better idea and yeah I don't mind the price difference, as I'll probably rent the truck anyway.  Does the support slab and insulating slab have to be poured on the same day?

No. I'd pour the support slab, cover it and let it cure for at least 24 hours before continuing with the insulation layer.

At my Lowes, they will do a cut on the plywood for you so if you can fit 48x55 and 48x41 pieces, you dont need a rental.

Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #153 on: May 15, 2019, 10:51:07 AM »

No. I'd pour the support slab, cover it and let it cure for at least 24 hours before continuing with the insulation layer.

At my Lowes, they will do a cut on the plywood for you so if you can fit 48x55 and 48x41 pieces, you dont need a rental.

Thank you.  It's supposed to rain tomorrow so that will be a fun challenge.  I wonder how I can coordinate the wood forms and the rain without a canopy; probably just using a tarp.  So the forms would have to stay on for over 30ish hours then, factoring in the insulating layer being poured after.

I can hopefully fit that in a Rogue.  I'll have to go measure; but definitely better than moving a 4x8.  I will calculate how many bags of concrete based on about less than 16 sq ft and 3.5" thickness, but for the Portland cement it doesn't seem like I'd need a lot because of the 5-1 perlite.

Also, what if the support blocks come up to 31.5" or so, which will be an inch higher than the stand; will that push the wood up?
« Last Edit: May 15, 2019, 12:14:51 PM by Pod4477 »

Offline foreplease

  • Lifetime Member
  • *
  • Posts: 5258
  • Age: 59
  • Location: St. Joseph, MI
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #154 on: May 15, 2019, 05:17:57 PM »
Also, what if the support blocks come up to 31.5" or so, which will be an inch higher than the stand; will that push the wood up?
Well yeah. Better to be too low than too high. The top edge of your concrete pad is what matters. The shape of the bottom edge matters very little, if at all. Try removing a little soil beneath the bottom block of each of your columns. You can no longer be concerned with plumb and level for this part. I suggest running 4 strings, 2 each end to end and side to side that cross in the 4 places your block will be. At each of those string crossings that is you maximum top block height. Since it appears they will be stacked straight up I suggest filling the cores and using a piece of rebar. I know it only needs to hold until you slab hardens but if one of the supports moves or topples over you will have a mess. I assume and hope those columns are not half blocks, they are shown as square on your drawing - or are you stacking them end on end and rising (almost) 16” with each one? If so, I don’t know how to stabilize that but it would be even more important IMO.


EDIT - Sorry, I see now that was Jon’s drawing. Maybe he can clarify.
-Tony

A D V E R T I S E M E N T


Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #155 on: May 15, 2019, 06:09:36 PM »
You're right. I screwed up. The way I have the block columns stacked is 3/4 of an inch too high. I must have typed it into the calculator wrong.

4x7.625 is 30.5
2x15.625 is 31.25

I suck.

Quick fix would be to take the 8 blocks from the 4 columns and make 2 columns stacked 4 high, same as the rest of stand walls.

Tony-  the blocks are only needed to support the wet concrete for about 12 hours,. Not the most stable thing, but good enough for the short term. When I did it like that for my oven, I had wood on top of the block because I wanted to take the forms down. Once the wood was out, it was still hard to move the block. The blocks I used had flat faces and they worked well in this way.

Offline foreplease

  • Lifetime Member
  • *
  • Posts: 5258
  • Age: 59
  • Location: St. Joseph, MI
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #156 on: May 15, 2019, 06:25:51 PM »
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.
-Tony

Offline Jon in Albany

  • Lifetime Member
  • *
  • Posts: 1744
  • Location: Albany, NY
    • Jon In Albany Blog
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #157 on: May 15, 2019, 06:44:16 PM »
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.
I know you didn't mean anything. It's more just me frustrated about offering advice for the past week and then basically forgetting to carry the 1 in the math.

Offline Pod4477

  • Registered User
  • Posts: 525
  • Location: Massachusetts
  • Pizza
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #158 on: May 15, 2019, 09:01:45 PM »
Well yeah. Better to be too low than too high. The top edge of your concrete pad is what matters. The shape of the bottom edge matters very little, if at all. Try removing a little soil beneath the bottom block of each of your columns. You can no longer be concerned with plumb and level for this part. I suggest running 4 strings, 2 each end to end and side to side that cross in the 4 places your block will be. At each of those string crossings that is you maximum top block height. Since it appears they will be stacked straight up I suggest filling the cores and using a piece of rebar. I know it only needs to hold until you slab hardens but if one of the supports moves or topples over you will have a mess. I assume and hope those columns are not half blocks, they are shown as square on your drawing - or are you stacking them end on end and rising (almost) 16” with each one? If so, I don’t know how to stabilize that but it would be even more important IMO.


EDIT - Sorry, I see now that was Jon’s drawing. Maybe he can clarify.

Yup I was thinking better to be too low than too high.  The string is a good idea!  Thank you. 

You're right. I screwed up. The way I have the block columns stacked is 3/4 of an inch too high. I must have typed it into the calculator wrong.

4x7.625 is 30.5
2x15.625 is 31.25

I suck.

Quick fix would be to take the 8 blocks from the 4 columns and make 2 columns stacked 4 high, same as the rest of stand walls.

Tony-  the blocks are only needed to support the wet concrete for about 12 hours,. Not the most stable thing, but good enough for the short term. When I did it like that for my oven, I had wood on top of the block because I wanted to take the forms down. Once the wood was out, it was still hard to move the block. The blocks I used had flat faces and they worked well in this way.

haha no, no worries; you and everyone have been a huge help.  Funny thing is that I did pretty much as you suggested here and stacked 8 blocks, 4 courses high, in the very middle to support the plywood pretty well.  I may fill the blocks to be solid as foreplease suggested, but I got them pretty level.  The plywood worked awesome too and I got 8 pieces of rebar to be 12" on center.  They will be a about a foot short on each side, but I could always splice some of my 15 scraps of cut rebar into them.  I got ties too and I wonder what I can cover the block cores with.  I've seen tin covers and empty concrete bags.  I also got the frame 2x8's but if forgot it will really be 7.75" or so high actually.  I also got a strap and corner brackets just incase, along with wood screws.  I got 2x4 legs, but I may have to put the frames on the block stand as one person did, just because of imperfections in the stand walls.  It's pretty plumb, but I feel it may not be 100% for the wood.  I'm sure if the concrete doesn't come all the way to the edge by about an inch, it may not matter as it will be covered by something in the future.
« Last Edit: May 15, 2019, 09:04:32 PM by Pod4477 »

Offline foreplease

  • Lifetime Member
  • *
  • Posts: 5258
  • Age: 59
  • Location: St. Joseph, MI
Re: Wanting to build a coal fired style outdoor pizza oven
« Reply #159 on: May 15, 2019, 09:27:54 PM »
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 :)
-Tony

A D V E R T I S E M E N T