The Morgan's WFO build Brick Oven Photos Discuss The Morgan's WFO build in the Good Background Information forums; Hi Les It's in there pretty far. I had to pull the blocks back to get them in. They are ...

[vintagemx0]

Hi Les
It's in there pretty far. I had to pull the blocks back to get them in. They are about 1" from the other interior side, so about 5.5 inches into each block.

My concern is this; Since they are cast in concrete and rigid, will it be a problem now that expansion stresses will not be able to relieve themselves? In otherwords, if the slab needs to expand/contract, will the rigidly secured rebar mesh create a problem such as drooping or heaving-up the slab, or cracking?

Ken

[Les]

That hasn't happened to my build. All the thermal issues are going on well above your hearth. I need to check my pic's but I think I ran my bar over to the other side - and it was just good enough. This build carries more weight then you can imagine. You might consider putting in a center post. If you want, I can find the formulas that people use to design bridges, etc... Back to thermal, at this point, it's not an issue.

Les...

[vintagemx0]

Good stuff Les, thanks.

With the depth of pentetration of the rebar into the block and the amount of concrete cast around them, I'm sure the only force that could fail the rebar is sheer - and I feel confident that won't be an issue. My concern was of the thermal issue. Now that I have the ends of the rebar rigidly set, will the slab fail due to expansion and/or contraction stresses having nowhere to go? It sounds like if I use an ample amount of insulation layer between the hearth and the structural slab, that the slab will never see extreme temperatures.

Do you think it would be wise for me to use a form that leaves a small gap between the structural slab and the blocks? I was planning to pour right-up to the blocks, but perhaps a 1/2" gap would provided some protection?

Thanks again,

Ken

[Les]

Originally Posted by vintagemx0

Good stuff Les, thanks.

With the depth of pentetration of the rebar into the block and the amount of concrete cast around them, I'm sure the only force that could fail the rebar is sheer - and I feel confident that won't be an issue.

That was my thinking - the issue is pull. Think of of it this way. You support a 8x11 piece of paper from the edges, put a small weight right at the support - no problem. Move it to the center and the paper will drop.

Originally Posted by vintagemx0

My concern was of the thermal issue. Now that I have the ends of the rebar rigidly set, will the slab fail due to expansion and/or contraction stresses having nowhere to go?

I think not, we have all buried the steel inside of the concrete - that is kinda what makes all this work.

Originally Posted by vintagemx0

It sounds like if I use an ample amount of insulation layer between the hearth and the structural slab, that the slab will never see extreme temperatures.

Exactly!

Originally Posted by vintagemx0

Do you think it would be wise for me to use a form that leaves a small gap between the structural slab and the blocks? I was planning to pour right-up to the blocks, but perhaps a 1/2" gap would provided some protection?

No need. Again, all the thermal is going on up top. Your enemy is pull. The P.E. I had run my Calc's even added 300 pounds of active weight. I asked him what the hell was that about and he said if I had to climb up on top to work on something. Guess what - I was climbing on top with an arm load of brick to finish my chimney.

Keep the questions coming - we are here to help. This is a great project, enjoy your build!

Les...

Ken[/QUOTE]

[vintagemx0]

Thank you Les.

I wish it had occurred to me to aske the question a few days ago...I could have very easily added the "hooks". I'm seriously considering a center pillar under the oven now. The small inconvenience of having the pillar in center of our large fuel storage area is nothing compared to the problems we could have if it pulled and drooped downward.

Thanks again, we'll definately keep the questions coming!

Ken

[vintagemx0]

We worked all weekend to "catch-up" a little on our project. We decided to go ahead and put a center support column beneath the hearth structural slab. We simply stacked some 8x8 concrete blocks and tied the top end into the forms and inserted two peices of rebar. The inside of the blocks were filled with concrete during the pour of the structural slab.



The form for the structural slab was pretty straight-forward, but the form for the 15 foot bench took all day Saturday to build and re-inforce. Here's a photo of the forms just prior to the pour...



And here's a photo shortly after the pour...



It's nice to have all the "heavy" work behind us. Next, we are going to route some drain pipe and take care of parts of our patio. The next stage on the oven will be the insulation slab and the oven dome.

The Morgan's

[Dino_Pizza]

Really nice work, good job with the steel. Looks like a strong structure. The whole area looks like it'll be a lot of fun to cook and entertain around. It's always great to be done with the heavy work, foundation, walls...etc.and get on to oven. Congratulations on nice job, Dino

[vintagemx0]

We've been busy working on our patio area... We put in a drain-field, brought in crushed gravel and sand, put in a small wood deck between the boundary of our lower patio and fence, made a small wood shed, installed pavers on our upper patio, and have begun a lighting scheme. So, now it's time to return to working on our oven.

We have enough firebricks to get started and have a couple large bags of Perlite. So, we need to settle on the finish for the landing so we can pour the insulation slab at the proper thickness. We hope to have the hearth laid before the weekend and to do the soldier course this weekend. We know we have a ways to go, but our aim is to have an end-of-summer pizza party.

Here's a couple of pics...





Ciao e presto!
Dixie and Ken Morgan

[vintagemx0]

We bought some HeatStop mortar, and then I read this morning how the wet pre-mix was water-soluble. Sigh... So, we did some research this morning and decided not to mess around and ordered some RefMix through Forno Bravo's e-store.

In the meanwile, we cut a lot of brick today and "dry-fit" much of them together...



Our grandaughter stayed the weekend with us, and she was inspired to erect her own "soldier course" of sorts...



We hope to have the hearth set tomorrow and perhaps cut a few more brick, but if the mortar arrives this next week, we should see some real progress by the end of next weekend.

Cheers!

Dixie and Ken

[Ken524]

Hi Dixie and Ken,

Your progress is outstanding, I love the patio!

We bought some HeatStop mortar, and then I read this morning how the wet pre-mix was water-soluble. Sigh... So, we did some research this morning and decided not to mess around and ordered some RefMix through Forno Bravo's e-store.

Yep, the pre-mixed stuff has to stay covered and protected until it's fired. The dry HeatStop is what many of us have used. You won't go wrong with FB's morter