Refractory mortar OVER Cal/sil board?

[Kjskjs]

Hi, newbie here. I have purchased the Premio 2G 100 kit. My pizza oven base slab is complete; 5” of reinforced concrete. Question about the floor insulation…My kit calls for 3” of cal/sil insulation board over my 5” slab, then 2” firebrick tiles. I have seen some builds (Firebrick Company)with 1” of castable refractory mortar OVER the insulation board used for adding thermal mass. I’m pretty sure my 3” of insulation board will provide ample insulation, but as far as thermal mass goes, do I need this 1” of mortar over the board or is this overkill? My dome is 3” thick so that should be enough mass on top but what do you think about adding that 1” mortar over the 3” of insulation board? Thanks!

[UtahBeehiver]

How do you want to use your oven? For most folks your 3" CaSi and 2" brick is great for pizzas and extended cooking the following days, extra thermal mass comes into play for those who want to do more bread baking.

[Kjskjs]

At this point, I’m thinking mostly pizzas, and some other things like veggies, meatballs during the primary cooking night. Maybe roasts and bread on day two. If there’s a huge advantage I don’t mind putting in the extra work, but didn’t know if anybody else builds their ovens this way, or if it’s just silly overkill.

[SableSprings]

Although adding more thermal mass underneath sounds good for extended baking, it will definitely impact the amount of wood needed to come up to pizza temps. With the standard insulation and 2" cooking floor, you've got the sweet spot for max efficiency and great extended cooking time. Russell is right on target with the added mass for extended cooking but if you're not looking for huge batches of bread coming out of a single firing, it's way overkill for us regular folks. I have baked 15-20 loaves of bread in my oven and my floor insulation is pretty poor compared to 3" of ceramic board you've got.

Also, if you overfire, cooling the thicker floor down so you can use it can be a serious problem on pizza night or bread day. I've done this a few times where my bread loaves need to go in but my oven floor temps are way too hot. Again for a few pizzas, some meatballs, and roasted appetizers, what you've got is going to be awesome! Relax & don't overthink a successful and proven design.