Premio 2G 100W - Forno Tito III

[JoeT62]

So.....having moved to the West coast and left my two WFOs behind (a self build 40" Pompeii and a FB prebuilt 28" Primavera) After going through the stages of lost WFO grief (Denial, Bargaining, KettlePizza, Roccbox, and Uuni) I decided I needed a true WFO here in Santa Rosa. I decided on the Premio 100 without the gas option.

A few questions/issues/observations:

1 - The oven is listed as having 3" of ceramic board insulation, but it all came in 2" sheets. I decided to go with 2" rather than 4" as this is what lies beneath the Casa series and about what I had on my Pompeii with excellent heat retention. My oven stand was already a bit high and I didn't want the extra elevation.

2 - I did set the ceramic board on a "bed" of mosaic ceramic tiles with the cut outs over four 1 1/2" weep holes. As I built my Pompeii 15years ago, this was new to me, but makes a lot of sense. I also imagine there may be some gain in R value with the tile and air gap above the concrete slab.

3 - The four main sections of the Premio 100 are HEAVY. Use good lifting techniques and plenty of extra help. The pry bar technique in the FB video was an excellent tip in getting the pieces properly spaced and set.

4 - I splurged and bought the FB brick arch. It's quite nicely done. A question: should I attach this to the front with refractory mortar? Standard? Fireplace cement?

5 - I am planning on an igloo closure and have a grand mosaic plan in my head of intertwining grape vines with a sun on the apex. I will be pre-setting the mosaic on fiberglass mesh and attaching it to the stucco. This will take time and in the meantime I want to complete and seal the stucco to prevent water ingress. Does anyone see an issue with the mosaic "sticking" to the stucco with thinset once it is sealed?

6 - My east coast oven was fully enclosed and as I mentioned, this one will be an igloo. Is there any consensus on creating a vent/blowhole in the dome to allow accumulated moisture to escape? How does one make sure it doesn't allow water in?

I am sure there will be more questions as I progress!

Finally, I want to say that I am ecstatic that this community is still here and thriving. I couldn't have built the Pompeii oven without this forum and I am looking forward to another WFO adventure!

[hillscp]

Welcome to California! I'm building my own Casa 100. We can send smoke signals over the coast range.

Scott
Chico

[JoeT62]

Scott -

Yes, I've seen the photos from your build - looking good!
I've been in CA five years now - moved here just in time to evacuate from the Tubbs fire (our house was spared but plenty of damage to our yard), and now finally getting around to putting in a WFO. I put a small brick landing on yesterday and will hopefully get the arch on this weekend. Then it's on to the blanket wrap and stucco!

Joe

[JoeT62]

Some progress and questions:

I have nearly finished a layer of perlcrete on top of my Premio 100. There is 4" of ceramic blanket between that and the oven. My original plan was to cover the blanket with lath and then do a 2 layer stucco application followed ultimately by thinset and a tile/glass mosaic. Despite heroic efforts by myself and several friends, we could never get the lath to "sit" right. Pull in one area and another would bulge, and so on. I finally took all the lath away and applied the perlcrete (about 1.5" thick) directly on top of the blanket as has been discussed. I used a 7:1 ratio of perlite to Portland with some clay thrown in. I tried 10:1 but it was too difficult to work with and I think I already have plenty of insulation. Once I build a scaffold I can get to the back of the oven and complete the perlcrete layer.

Questions:

Any value to a scratch/brown coat now or should I go straight to the finish coat for the stucco?
Any consensus on how to seal the dome and which product works best?
I am planning on a layer of thinset/mosaic on top of the stucco, but that is for the future and will take me a fair amount of time to prep. In the meantime I would like the oven to have a finished look and be sealed. I am worried about any sealant and or paint interfering with the thinset "sticking" or am I overthinking that?

Thanks!

[david s]

Some progress and questions:

I have nearly finished a layer of perlcrete on top of my Premio 100. There is 4" of ceramic blanket between that and the oven. My original plan was to cover the blanket with lath and then do a 2 layer stucco application followed ultimately by thinset and a tile/glass mosaic. Despite heroic efforts by myself and several friends, we could never get the lath to "sit" right. Pull in one area and another would bulge, and so on. I finally took all the lath away and applied the perlcrete (about 1.5" thick) directly on top of the blanket as has been discussed. I used a 7:1 ratio of perlite to Portland with some clay thrown in. I tried 10:1 but it was too difficult to work with and I think I already have plenty of insulation. Once I build a scaffold I can get to the back of the oven and complete the perlcrete layer.

Questions:

Any value to a scratch/brown coat now or should I go straight to the finish coat for the stucco?
Any consensus on how to seal the dome and which product works best?
I am planning on a layer of thinset/mosaic on top of the stucco, but that is for the future and will take me a fair amount of time to prep. In the meantime I would like the oven to have a finished look and be sealed. I am worried about any sealant and or paint interfering with the thinset "sticking" or am I overthinking that?

Thanks!

I agree about the lath application, it is so time consuming. The beauty of the perlcrete layer is that it can easily even out the bumps and uneven surface left by the blanket layers. It only has to be really lean if you also want it to insulate. In your case 4" of blanket is plenty so any additional insulation provided by the perlcrete is really not required. The problem is that it requires so much water in the mix. If you have used 100 litres of perlcrete then you will have added probably more than 30 litres of water 9depending on the grade of perlite used). That means after hydration of the cement that there is still a lot of water in your insulation layer. It is best to do some drying fires after a week, allowing the sun and wind to dry the perlcrete, when you have completed the drying fires and the inside of the oven has all turned white, you should be able to safely render over the oven with your stucco layer(s). Instead of doing the stucco in three layers, I do it in one 12-15mm layer (to save labour), but I do add AR random mixed fibreglass fibres to reinforce that layer. On completion of the layer a wet sponge will remove any tooling marks and leave a nice surface.

There are many ways to skin a cat.

[JoeT62]

Thanks, David! Much appreciated. I will look into getting some of that fiberglass fiber. Any thoughts on sealer?

I was planning on doing just like you say - finish the perlcrete and allow at least a week of "natural drying" before starting any drying fires. Then I was planning on going slooooow with the fires.

I did put in weep holes and put my insulation board on top of mosaic tile with channels leading to the holes. What is your opinion on a "blow hole" in the dome to release any intermittent moisture? I am in northern California - usually dry but when it rains it can RAIN. I am thinking I will also fashion a cover for the rainy season.

[david s]

A steam release somewhere in the outer shell is a good idea. It’s like the little hole in a saucepan lid and can reduce steam pressure build up under the outer shell. In my build the insulation space can vent to the atmosphere around the base of the flue pipe and out between two terracotta caps that support and seal the flue pipe from weather. You could drill a few holes in the base of the flue pipe that are surrounded by the lean porous vermicrete, seal between the outer render and the pipe with high temp silicon, so moisture in the insulation space has an exit to the flue pipe.
There are many types of sealers to waterproof the outer shell, I use an acrylic product called flexible pointing, designed to seal and bridge cracks in the mortar for tiled roof ridge caps, watered down 20% so it can be applied by brush. Three coats results in around 1-2 mm thick very flexible impervious coating that would also be suitable to tile over.

[JoeT62]

Exit to the flue pipe! That's brilliant!