Nathan's 36" SoCal WFO build

[n8huntsman]

I've been working on a roof and deck for my outdoor kitchen for about a year. Outdoor kitchen thread is here: http://www.fornobravo.com/forum/f35/...ild-20331.html

Since I just started on the WFO, I guess it's time to start a thread for it.

Here is the initial design.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

I'm going to start filling the cores today. I still need to figure out how to span the opening while supporting the concrete hearth.

[Tonyp]

Re: Nathan's 36" SoCal WFO build

Hi Nathan,

I was looking at your other thread earlier. Looking nice! I really like the decking you put down.

Not sure I fully understand what you mean by span the opening. Do you mean across the front between the gap in the blocks? The concrete hearth reinforced properly with rebar shouldn't need any support under it once cured. I think most people use concrete backer board under the hearth to make the pour. You just need to support the backer board from underneath to hold the weight of the uncured concrete. Not sure what your plans are for finishing the outside of the block and oven but do keep in mind keeping the occasional rain from getting into your insulation/cooking floor. One of the ways that can happen is via the block wall. So you might consider a moisture barrier between the top of the block and the bottom of the hearth slab, if not there then between the top of the hearth slab and bottom of the insulation layer.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Hi Nathan,

I was looking at your other thread earlier. Looking nice! I really like the decking you put down.

Not sure I fully understand what you mean by span the opening. Do you mean across the front between the gap in the blocks? The concrete hearth reinforced properly with rebar shouldn't need any support under it once cured. I think most people use concrete backer board under the hearth to make the pour. You just need to support the backer board from underneath to hold the weight of the uncured concrete. Not sure what your plans are for finishing the outside of the block and oven but do keep in mind keeping the occasional rain from getting into your insulation/cooking floor. One of the ways that can happen is via the block wall. So you might consider a moisture barrier between the top of the block and the bottom of the hearth slab, if not there then between the top of the hearth slab and bottom of the insulation layer.

You are correct, I meant across the front between the gap in the blocks. I see most people use some angle iron with an additional two block on top. My opening is only 16" so I opted to omit that block across the top to increase my limited access to the inside. Good to know that it will be okay without the angle iron.

I haven't decided yet how I'm going to finish it. Leaning towards either a beehive with some sort of stucco, or building an enclosure with some sort of fa?ade.

I can see how a moisture barrier between the hearth and bottom of the insulation would help. What do most people use for this?

You also mention a moisture barrier between the top of the block and the bottom of the hearth slab... are you saying that the insulation will wick moisture up from the block?

[Tonyp]

Re: Nathan's 36" SoCal WFO build

Hi Nathan,

I can't imagine you would have an issue spanning across the opening in front between the blocks. In addition to the rebar grid throughout the concrete slab, I would probably put a couple pieces of 1/2" rebar a few inches apart across that gap.

As far as a moisture barrier, my build is fairly unconventional and indoors so moisture is not an issue. Hopefully someone with more knowledge about outdoor builds and potential issues with moisture getting into the insulation and hearth brick layer can give you advice. I have read many build threads so am only going on what I have seen others do in these situations.

My understanding is the potential for moisture to travel up the block wall and into the hearth from below. So a moisture barrier is a good plan, either between the top of the block and concrete hearth or between the concrete hearth and insulation layer. I think if it were me I would be looking at some 2mil plastic on top of the block that way if for some reason moisture did get into the concrete hearth or the insulation layer above it, air could get at from below.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

I decided I needed a small landing in front of the arch because I need a lip to conceal the stacked stone (not shown) that will be placed on the face of the block stand.

I was thinking about getting rid of the bricks that are shown under the arch and replacing it with concrete poured in a single pour with the curved landing. The arch would be built on top of the concrete instead of the brick. Of course I'd have to separate it and the arch from the cooking floor and dome with a thermal break.

Are there any drawbacks in doing that?

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Here is what I was thinking about above. It makes the stacked stone and concrete much nicer. I think this is how I'm gonna do it. I just gotta figure out how to do the thermal break.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Called around the local shops today to find out what kinda of firebrick I can get and what the cost is.
I can get the following:
Pacific Clay - $1.33
HC Muddox - $1.75
Whitacre - $1.86

The Pacific Clay is a little light on the alumina content, 21%. I've read that that will still be fine for a pizza oven. With those prices, does that sound like the logical choice?
Thanks

[deejayoh]

Re: Nathan's 36" SoCal WFO build

The floor inside your oven arch gets pretty hot - even with a thermal break. I am skeptical that concrete is going to do well with the heating/cooling cycles. I have the same design - poured concrete counter flush w/oven floor - and used soapstone in the entry. It has held up well. Was a bit tough to source though

As to the bricks, light duty should be fine. That's what I used.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

I can pull the concrete back some. I'm working on a more detailed 3D model now. The original one was simple revolutions. I'm not building one brick by brick. Once I get the arch transition modeled I can see where I'm at on the floor. I'll keep posting my model snapshots to get feedback to hopefully make my mistakes on paper, before cutting and mortaring bricks. Those are harder to fix.

For my model, what do people think is a good mortar thickness to shoot for? I plan on tapering my bricks in the dome on 4 sides, aiming for a uniform mortar joint on 4 sides. I started with 1/8" but after looking at countless builds, it looks like even with the most detail oriented cuts in the brick you still end up with what looks like 1/4". Is that more realistic? I realize it will be next to impossible to built to my model but I want to get as close as possible.

[deejayoh]

Re: Nathan's 36" SoCal WFO build

Couple things
1) I don't think it's worth it to taper bricks on all four sides. I don't know of any builders that have tapered top and bottom. Better to do a compound taper on the sides to account for tilt and then just tip the bricks using mortar to support them.
2) as such, mortar thickness won't be even across the brick. Shoot for tight mortar lines at the front - 1/8 is probably reasonable. At the back, you'll have thicker mortar. Maybe 3/8 inch. That's fine. It doesn't hold the bricks together, it holds them apart so that the dome can be structurally sound.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

I guess cutting all four sides is easy to say for someone who hadn't cut a single brick yet, lol. Now I'm torn. I really want to try it, especially because you say you haven't seen it... but I don't want to back myself into a corner either... decisions decisions.

[Toomulla]

Re: Nathan's 36" SoCal WFO build

Couple things
1) I don't think it's worth it to taper bricks on all four sides. I don't know of any builders that have tapered top and bottom. Better to do a compound taper on the sides to account for tilt and then just tip the bricks using mortar to support them.
2) as such, mortar thickness won't be even across the brick. Shoot for tight mortar lines at the front - 1/8 is probably reasonable. At the back, you'll have thicker mortar. Maybe 3/8 inch. That's fine. It doesn't hold the bricks together, it holds them apart so that the dome can be structurally sound.

If you purchase tapered bricks and set your oven size to the arch that the taper creates you only have to cut the sides . If you try this don't forget to use a spacer in the joints when you check the arch/ oven radius.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

I think finding tapered bricks around here is going to be tough and costly. Plus I am limited on space so it pretty much has to be ?36". I'm gonna model it cut 4 sides and see where it goes from there. I'm sure I'm going to end up redrawing everything anyways. So with that being said here is my floor and first course. Please chime in if I've screwed up anything in the images to follow because I want to make the mistakes here first.
Thanks

[deejayoh]

Re: Nathan's 36" SoCal WFO build

I guess cutting all four sides is easy to say for someone who hadn't cut a single brick yet, lol. Now I'm torn. I really want to try it, especially because you say you haven't seen it... but I don't want to back myself into a corner either... decisions decisions.

I am sure others can weigh in - but there's a reason you don't see any 4-sided tapers. The extra two cuts don't provide ANY advantage. The reason for tapering the sides is to get rid of the mortar triangle between the bricks inside the oven. There is no corresponding problem on the top/bottom. The bricks fit flush, every time, all the time. Cutting the top and bottom is a big waste of time and materials, imho.