Casa2g90 Install in Portland, Oregon

[ASPLM]

Well, my Casa 2g90 just arrived last night, so I guess it's time to start my thread.

We have a long narrow triangle of a backyard in Portland, Oregon. We wanted a reason to go to the back end of the yard and in a moment of internet inspiration based off a "Build a pizza oven for $150!" youtube video, my wife sent me on my own personal Pizza Quest (which is definitely NOT $150).

We put down a nice circular patio in July 2017, I poured my slab in Sept 2017, built my stand base when it warmed up in APRIL 2018, and we poured the counter in late MAY 2018. So far my only real hiccup was that I think I poured the counter a bit dry, but my concrete friends assure me I'm golden. I guess we'll see if it collapses when I get the oven up there.

Now I'm preparing to lug the kit up onto the main counter and I have many questions:

1) How do I secure the lathe to the oven? Do I screw it to the counter? The insulating base seems very fragile and not a good place to screw.

2) The video shows using two different kinds of stucco to finish, but then mentions that the marble stucco is harder to work with but more durable. Since it will be an outdoor oven, I want maximum durability and waterproofness (I'll tarp it in the winter). So I think I should use the marble stucco for both layers. But am I really going to gain a lot in waterproofing and durability, or is it not worth the extra effort?

3} How can I seal off the edges of the insulating base because it seems like it would wick water and degrade pretty significantly if it's not robustly sealed. I've seen mention of high temp silicone caulk for around the chimney, so I'm currently thinking of putting a big bead of that around the outside edge of the whole oven once it's stuccoed and finished with acrylic.

MANY more questions to come, so bear with me.

My favorite comment to date from a dear friend is: "Seems like a lot of money to spend on a hornet's nest".


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Let the kibbitzing commence!

[Gulf]

Hi ASPLM,

Congratulation on the oven. You have a lot of good questions. I'm going to concentrate on two of them for now.

(1) I don't see a concrete pad in your oven kit. I'm assuming that is an option that you may have opted out on since you have a concrete stand. The pad is what the lath is normaly secured to.

(2) You are correct about it being difficult to seal the "insulating base". That is going to be a problem.

You can solve both of those issues by elevating your oven off of the concrete stand. Place or paint a waterproof membrane on your stand directly under where your oven will sit. You can lay concrete pavers over that. There are other ways to elevate, forming and pouring more concrete is one option. Ordering the concrete pad from Forno Bravo is another. Which ever option you select should be the actual shape and foot print of your oven. That will allow you to attach your lath securely and will put your oven up high and dry above the concrete stand.

I'm going to alert Alex_FB The Forno Bravo team has direct experience with the installing the Casa.

PS: Invite your friend over for some grub. However, if you invite the friend over too much, the friend wont have a reason to buy a "hornet's nest" of their own .

[SableSprings]

Hi ASPLM! I'm down in Roseburg and helped install an older version of the Casa2g90 in Canada several years back. One of the best methods to keep water from seeping into your insulation is to place a layer of Foamglas underneath the ceramic board. Foamglas is a great high temp insulation board that does not absorb (or provide capillary action ) transferring water to the ceramic board that loves to soak up water. I just did an online search and it appears the Bay Insulation Company in Portland may carry it. The demand wasn't good for the residential market but it still has plenty of value in the commercial market. You might even be able to find a builder with "scraps".

Since your concrete is green, you might consider drilling 5-6 weep holes through your hearth under the future oven location before you set the floor. If you do get some water in along the base seam, these allow the water an easier exit route. When we did our Casa90 in Canada, we laid some chicken wire on the hearth and then set the ceramic board on top. When we finished applying the mortar to the dome seams and laid the ceramic batting over the dome, we just pulled up the chicken wire and cut & tied it tight over the insulation. Stucco was applied directly onto the chicken wire after we cured the oven.

I'll be back online a little later this evening and will try to go over some other options for waterproofing and creating a water dam around the dome perimeter (if you don't think the Foamglas option will be available to you).

[SableSprings]

As to making your future dome waterproof, I think water resistant will be a better way to think. There are additives for concrete and mortar that are pretty effective...but water seems to always have the final "win". No matter how good the product and your installation efforts, it will need to be maintained and repaired as needed (IMHO ). You can also build a little dam (concrete or mortar) around the finished dome perimeter and paint it with one of the flexible sealers like Redgard (used in shower stalls & floors). Gulf mentioned using something like this for your hearth in his post (#6) above. The final coat of stucco/render would simply cover it along with the dome's lath and insulation blanket.

I've added a picture of a perimeter around my build in which I embedded heavier wire for a perlcrete insulation layer over my dome. You could do something similar or simply use concrete screws to secure the lath or wire. We built an outside den than covers the oven and gives us a place to not only make pizza and bread without rain, snow, or bugs. I think you would be able to enjoy and use your oven a lot more if you think about adding a small enclosure/cover that would at least give you a dry place for the pizza (pre & post) and the cook during that sudden shower coming down from the gorge

Setting your oven up is something you need to think about and prepare carefully. Your outside render/stucco + insulation layer thickness needs to be included in the space you leave on the outside of the dome. Lots of builders have set or built their dome too close to the edge of the hearth slab and find it near impossible to secure the batting or finish the outside of the oven as they originally planned. Again, I would strongly advise drilling those 1/4"-3/8" weep holes before you set anything on top. As the pieces are pretty heavy, it's a good idea to clearly mark perimeter and join areas on the top of the concrete...place it correctly the first time.

When you set the Casa2g90's ceramic board down on the hearth, it should only need a little layer of moist builders sand and clay on top to level the cooking floor tiles. When we set the outer dome pieces into place on the perimeter of the same base boards, they caused the cooking floor tiles to lift up a bit unevenly. It wasn't major, but the cooking floor isn't as level as it should be. We probably should have reset it, but the tiles in the back only had a little lip that did not affect loading (only pulling ash out). The oven has produced a lot of very fine bread, pizza, steaks, roasts, pies, and even a suckling pig over the years since we installed it...so I'm sure you're going to love it!

Now is not the time to rush...relax and enjoy the process. Don't be afraid to ask questions, lots of folks here with lots of experience...keep posting!

[ASPLM]

Wow! What a ton of great suggestions! Thank you!

Gulf, when you say place or paint a waterproof membrane, can I just put visqueen under the pavers? Or will that get too hot. If not visqueen, do you have another suggestion.

Gulf/Sable Springs, how big of weep holes?

Sable Springs, I love the chicken-wire wrap idea, and I assume the ceramic base is pliable enough that the chicken-wire just embeds itself and doesn't affect level in any way.

Regarding the cover, maybe some time in the future. My wife is reaching the limit on her budget for this project. For now, we have a big canopy we can use if weather threatens, and I'll tarp it when not in use.


Three new questions:

1) I'm sure this is a dumb question because why woutd FB use it if it were a problem but the insulating platform seems really fragile. Is it really going to hold level and not compress and degrade over time (provided I keep it dry)?

2) Anybody have an opinion on my stucco question above (use standard stucco followed by marble finish, or use two layers of marble finish stucco), or a recommendation on a particular stucco product for wet climates?

3) When's the best time to start curing fires?

a) Before installing the insulation blankets?

b) After installing the insulation blankets but before applying stucco?

c) After applying stucco, but before applying the acrylic coating?

d) After applying the acrylic coating, but before applying a finish mosaic?

e) After applying EVERYTHING?

f) Do some kind of cure after each of those steps

[SableSprings]

Gulf was looking at minimizing water/pathways to the insulation. Generally, there are 5 "normal" paths of water to your insulation; 1) Capillary action up from the concrete base; 2) Seepage in from the oven perimeter joint with stand; 3) Through cracks in the outer render; 4) Down the flue; and 5) Through the front oven opening.

1) By putting down visqueen or painting a water sealant (like Redgard), you cut off the water coming up from the stand.
2) Creating a barrier from perimeter seepage is usually done by lifting the ceramic board up on some material that will not wick moisture (that's the purpose of my Foamglas suggestion). I'm actually thinking that putting down a layer of 2"-3" of perlite would also provide that barrier. Much less expensive than Foamglas, but would need to have an outer containment ring since it's loose material.
3) Addition of a waterproofing agent to your dome's stucco layers (some suggest painting Redgard over the first layer and then final coat over that).
4) Chimney caps (with cinder guards/mesh in our area) help minimize water coming down the flue.
5) Slightly angling your landing/entry away from the oven opening or by providing a small gutter just outside the door seat area that also acts as an expansion gap for the oven when heating.

By drilling 3/8" - 1/2" holes in the concrete base under your oven, you are simply providing an escape route for any water that does get into the oven base area.

When we used the chicken wire base wrap, we cut one long piece and one shorter piece. We placed the short piece down- headed out the back and then the longer piece centered left/right. On top of the wire went the ceramic board and a thin layer of moist sand/clay. The cooking floor pieces were set in place and leveled. Next we put the cast oven pieces on, mortared the seams, and applied the ceramic batting. Next we lifted the three ends of the chicken wire up, cut as needed to get them to form over the dome. The chicken wire was secured with small wire pieces and cut pieces from the excess chicken wire.

A couple of thoughts; you don't have to make the chicken wire long enough to go over the top. You can just make then long enough to extend a foot or so up the dome batting. Then you would finish by cutting and placing wire over the top and securing it to the "base wire". That loose wire is a bit of a pain to work around until you get the weight of the cooking floor tiles in place. That's why I'd go either short or longer than needed. The wire itself just pressed into the ceramic board on the base...no leveling issues.

New questions/answers
1) Ceramic board is very crumbly and can absorb water to the point where it's the consistency (and strength) of a wet sponge .... However it's compression strength is very good. You can practically drive a car on it. So, no worries...it will work just fine to support the weight of your oven.

2) I didn't like stucco finish because we were using a color additive and needed to make multiple small batches because it was drying too fast. The thin outer layers cracked pretty quickly, but we only had a waterproofing agent in the base layer...I just thought the look was a little off what I expected. I'm hoping you'll get more input on methods and material improvements over the last seven years.

3) David S, our resident casting expert really promotes starting the curing fires after the insulation batting has been secured over the oven. More even temperature control/distribution. That said, there has been plenty of success curing prior to insulating the dome. At this point, I'm with David on this.

Moisture coming out of the oven refractory/structure can produce significant steam. Because of the need for the steam to escape, you don't want to apply any outer render over the blanket until the curing process is complete (IMHO ).

Sorry about the length of this answer...I hope it made sense or at least helped you understand the process a bit more. I've also attached a couple of pictures of the Casa2g90 build with chicken wire showing pre and post wrap, stucco application, scratch coat, and final.

[UtahBeehiver]

1. FB insulation board is AlSi with a compressive strength of 500 kpa or about 72 psi. Most CaSi board is also in this range (I used ThermoGold 12 at 100 PSI and FoamGlas @90 PIS). Both of these board material have good compressive strength but not shear or abrasive strength but on a level and solid concrete hearth they are just fine. You do need to be careful about rubbing the material while you install the oven, insulation, stucco, etc. If you need to cut the material I suggest you were a Noish 95 dust mask, 3 bucks or so at the big box stores.

2. You need to talk to a stucco supplier about making the oven water resistance (especially in your area).and not having a cover structure over the oven.
3. Current thought is after the insulation blanket is on to minimize temperature delta between inside and outside of the oven to lessen the change of cracks.
4. Curing needs to be a slow and temperature regulated.
Many of us have started with briquettes for the first few times, the temp is some what lower and transitional and you will not get a temp spike on the dome like you would with an overzelous wood fire. Added benefit, you can could yourself something like a dutch oven or tuscan grill or even Caveman steaks (you have to look that one up).

Since Mike is from Roseville, he is a good resource for your area, his oven is enclosed in a structure though.

A couple of 1/2" holes should be fine. Gulf glued some screen over his to keep the bugs out.

One of the most common problems with ovens that the not protected from the elements is water getting on the hearth and saturating the floor insulation resulting it the floor never heating correcting until it is dried out again. We see this quite often.

[ASPLM]

Excellent. I'll definitely get it up off the hearth, probably on pavers with visqueen beneath (or if I can get the FoamGlas for a reasonable price, I'll go that route). And I'll put in the weep holes.

Thanks for clarifying on the order of operations for curing. Very helpful.

[UtahBeehiver]

FoamGlas is just as expensive as CaSi or AlSi. I paid abt $100 for 21 sq ft in 2012. Distrubtion International is where I got mine, there is an office in Portland.

[ASPLM]

Eh.. it's still cheaper than owning a boat.

[ASPLM]

Latest progress from this weekend. Remember kids! Make sure you’re not on the casa100 page of the manual when mapping your Casa 90 redguard paint!!