Questions, Questions, Questions Tools, Tips and Techniques Discuss Questions, Questions, Questions in the Pizza Oven Design and Installation forums; Being that the outside of the oven is rectangular in shape and not domed, I am still a little confused ...

[Dan94550]

Being that the outside of the oven is rectangular in shape and not domed, I am still a little confused on how to assemble. Here is what I get from what I am reading, do not mortar the joints but cover the joints with 1" X 2"-3" refractory motar, cover with insulating (refractory) blanket, frame in, and back-fill voids with loose vermiculite. The walls are 4" - 6" thick so I don't think I will coat the entire oven with the mortar.

I will now order another bag of refrax mortar and the insulating blanket from FB.

[maver]

That plan to thickly cover the outside of the joints with mortar rather than put a thin mortar layer in the joint seems odd to me. I am certainly no mason, but why not just use refractory mortar in the joint? It should be much stronger than covering the outside of the joint, and will probably use less mortar. Your walls are quite thick, so I agree, no cladding. You'll be glad you are using the insulating blanket. It will be much easier to work with than loose fill around the walls.

[jwnorris]

Originally Posted by FB Casa Installation Manual

Seal your oven in two steps. First, using refractory mortar, seal each joint the oven dome; between the oven dome and the insulating hearth; between the oven dome and oven vent; and between the decorative arch and the oven chamber.

Moisten each joint using a sponge, then seal the oven joints by applying a 2"H x 4"W strip of refractory mortar cross the outside of the seam. Do not put mortar inside the joint as thermal expansion could cause the oven to crack. Seal the oven dome to the insulating hearth with a 2"W x 4"H strip of refractory mortar, the seal the oven dome to the vent and arch.

I took the above from the FB Casa installation manual. This is a seal and is not meant to connect the two dome [for lack of a better term] pieces together. It is for thermal expansion.

Dan, i think that you re-cap is going to work fine.

J W

[Dan94550]

Originally Posted by maver

That plan to thickly cover the outside of the joints with mortar rather than put a thin mortar layer in the joint seems odd to me. I am certainly no mason, but why not just use refractory mortar in the joint? It should be much stronger than covering the outside of the joint, and will probably use less mortar. Your walls are quite thick, so I agree, no cladding. You'll be glad you are using the insulating blanket. It will be much easier to work with than loose fill around the walls.

I am not a mason either. This is why I am throwing these questions out there and I'm getting more and more confused as there are different techniques. All I know is that I will use the blanket and still use the loose vermiculite to fill in any voids.

Maybe I'll start a new thread with a poll if I can't get an answer that I'm satisfied with.

Pros or cons on either method would be greatly appreciated.

[Dan94550]

Originally Posted by jwnorris

I took the above from the FB Casa installation manual. This is a seal and is not meant to connect the two dome [for lack of a better term] pieces together. It is for thermal expansion.

Dan, i think that you re-cap is going to work fine.

J W

What does this mean?

[maver]

JW - that's good information and certainly looks like a fine way to solve Dan's problem, but the casa ovens are certainly thinner walled than Dan's oven. If the goal is just to seal it, I still wonder if a paste of fireclay within the joints might be a good option. Yours is a casa oven, right JW? So yours has a re-cap (refractory mortar cap?) over the joints?

Marc

[james]

I can jump in here.

With a precast oven (such as the FB Casa or Premio), you use a band of refractory mortar outside the joint, without pointing mortar into the joint. That completely seals the oven and keeps all the heat and air inside the oven chamber.

If you want to add more mass to the oven, you can also coat the rest of the dome with 1/2"-1 1/2" of refractory mortar. That will give you more mass for retained heat baking (such as bread), and will require a slightly longer heat up time.

The reason you seal the outside of the joint is to allow for thermal expansion and contract. Otherwise, the mortar inside the joint would eventually crack and fall in. Our oven producer (and experience) is really clear on this one.

Personally, I have owned both a coated and a non-coated Casa90. They both work great, so I think it really comes down to how you want to use your oven.

I hope this help with the other question -- on why to seal the outside, not the inside, mortar, etc.

James

[Dan94550]

Originally Posted by james

I can jump in here.

With a precast oven (such as the FB Casa or Premio), you use a band of refractory mortar outside the joint, without pointing mortar into the joint. That completely seals the oven and keeps all the heat and air inside the oven chamber.

If you want to add more mass to the oven, you can also coat the rest of the dome with 1/2"-1 1/2" of refractory mortar. That will give you more mass for retained heat baking (such as bread), and will require a slightly longer heat up time.

The reason you seal the outside of the joint is to allow for thermal expansion and contract. Otherwise, the mortar inside the joint would eventually crack and fall in. Our oven producer (and experience) is really clear on this one.

Personally, I have owned both a coated and a non-coated Casa90. They both work great, so I think it really comes down to how you want to use your oven.

I hope this help with the other question -- on why to seal the outside, not the inside, mortar, etc.

James

Thanks for chiming in James. Makes sense now that you mention about the mortar falling inside if the joints are filled. I tend to dislike gritty pizza I will definitely put the band around the outside but I probably won't coat the entire oven given the wall thickness. I am going to the online store to order another bag of refrax and insulation now.

[fredjana]

Sounds like I heard two opinions on when to start curing the oven. Is it recommended to insulate and enclose the oven, then cure, or cure before insulating? If it matters, I am building a gabled house with therm blanket and loose vermiculite as insulation.

Thanks.

Fred

[Dan94550]

Originally Posted by fredjana

Sounds like I heard two opinions on when to start curing the oven. Is it recommended to insulate and enclose the oven, then cure, or cure before insulating? If it matters, I am building a gabled house with therm blanket and loose vermiculite as insulation.

Thanks.

Fred

Fred, I'm doing the same thing, so hope someone will answer the question.

Dan