Nathan's 36" SoCal WFO build

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

With everything except the stucco and some stonework done, Im switching back to my kithen/bar thread: http://www.fornobravo.com/forum/f35/...ild-20331.html

Ill post the final pics here too when Im done in a few weeks. Thanks to everyone who has helped make the oven a success as far as I'm concerned! Couldn't have done it without you guys.

[david s]

Re: Nathan's 36" SoCal WFO build

Leave your vermicrete layer at least a week to dry before adding the stucco layer. As vermicrete consists of a third of its volume as water there is lots to dry. As your oven is under cover the layer is not going to see any sun so drying may take longer. if you don't allow it to dry you risk cracking the stucco layer when the water in the insulation layer turns to steam. You can still use the oven to cook with in the meantime and the fires will help it dry. When you think it's dry throw some plastic over it to see if any water condenses under the plastic.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Planning on finishing up the vermicrete and getting the scratch coat and possibly the brown coat of stucco down this weekend. I know the stucco is supposed to be kept wet. Does that mean that trying to cook a couple pizzas this memorial day would be a bad idea? With 4 inches of CF blanket and 2" of vermicrete, not sure how much heat will actually make its way to the stucco...

[Greenman]

Re: Nathan's 36" SoCal WFO build

I agree, vermicrete is like trying to render with wet puffed rice - only more difficult! I developed a place and smear technique that seemed to work but I found it was something to do and leave alone. Messing with it was courting trouble!

There is no reason to wait to start the stucco/render process. It would be a good idea to give the vermicrete time enough to set properly and the top to dry a bit before messing with it just so it maintains its integrity. The stucco coat will allow moisture to escape, just need to leave it until the whole thing has dried before the sealing coat.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

I took a grinder and ground out the biggest cracks. Remortared them then wrapped the dome in 4" of CF blanket. After that things were kinda lumpy and I needed a way to conceal my 1/2" EMT that leads out of my thermocouple J-box. I decided to use a couple inches of vermicrete to do so. I assume that if I tried to lay stucco (render) scratch coat that thick it would crack. Probably would have been fine using some other type of mortar but I figured the added insulation wouldn't hurt. Wow, this vermicrete stuff is a PITA! Once I'm done with the extra vermicrete can I go directly to scratch and brown, continuing to keep things moist or should I do some sort of drying of the vermicrete before trying to do the scratch and brown. I know that needs to be kept moist too so I don't see what it would hurt to do it all at once, let it cure then do the final color coat of stucco??

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

One interesting thing to note is that all of the separations of the mortar from the brick are on the non-buttered side. I'm left handed so when I hold the brick in my right hand, I butter the bottom and left side of the brick then set it in place. All of the cracks are on the top and right sides of the bricks. For some reason it seems I don't get as good of adhesion on the side that I'm sticking the brick to. I guess pressing the mortar into the brick with the trowel adds to the adhesion. Does anybody butter both sides or "back-butter" as I've heard it called?

[Novaslo]

Re: Nathan's 36" SoCal WFO build

I agree, use a very liquid type home brew and get those cracks filled to give you piece of mind. Ultimately, I doubt that it will be structural problem.

Start cooking and then don't look back.

[david s]

Re: Nathan's 36" SoCal WFO build

Any thoughts on those cracks? Going to be time to insulate it shortly.

I presume you did the drying fires with the oven uninsulated. Doing it this way results in a bigger difference in outside temp and inside temp which leads to stress. You probably also went at it too fast. No point in crying over spilt milk. I'd be squishing in some homebrew into the cracks and also building up a layer over the top of the crack, then proceed with the blanket.

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Ok. Sounds like I'll be good to go on the insulation then. I'm not really disappointed. I kinda expected it from what I read. Just wasn't sure if I should fill them or not. My gut tells me there is no need.

[DavidApp]

Re: Nathan's 36" SoCal WFO build

Hello Nathan

I am not sure but I imagine most ovens have some cracks if you take a close look. Uneven heating causing expansion that has to go somewhere. Very unlikely to cause structural failure. Just a bit disappointing after all the hard work.

I had a coat of mortar and one layer of insulation on before I started my firing so I do not know if I have similar cracks in the dome. I do have a crack in the inner arch that has opened up to about 1/16" and stayed there. I can not see any evidence of cracks on the inside of the dome.

David

[n8huntsman]

Re: Nathan's 36" SoCal WFO build

Any thoughts on those cracks? Going to be time to insulate it shortly.

[n8huntsman]

It’s all finally starting to come together.

[n8huntsman]

Cracks!

Somewhere around 350?F the cracks started to open up. I haven’t seen any smoke come from any of them. Should I grind these out and re-mortar, or will they just come back? I assume these are normal expansion cracks and nothing to worry about?
Also, last night when I first fired it up and was getting a lot of smoke through the chimney, the stainless thermal break face got pretty hot and broke free from the mortar as the metal started to curl a bit. It was a pretty loud pop, scared me a bit till I figured out what it was. You can see the separation in the photo. Once it cooled off it came right back but I’m going to have to come up with something to prevent that or I’ll never get a good seal there.

[n8huntsman]

First fire!

First fire! Seems to be drawing just fine, even without the chimney attached. Very little smoke out the front. The last photo shows the chimney attached with the 45° elbows.

[n8huntsman]

Finally got around to finishing the entry arch and chimney last week.