OK. In the past 24 hours I've gone from 'hey, people seem to have good things to say about that Weber grill pizza oven thing' to reading all 40 pages of this thread, to pricing parts from craigslist, harbor freight, Amazon, and a dozen other places. At this point it's late, I'm a little twitchy, and I have questions. Forgive my enthusiasm and my overthinking.
I'm starting to pick up the importance of, and difference between, adding thermal mass and adding insulation. Traditional WFOs have got a lot of thermal mass above, and a lot below. The LBE has got plenty below (as beefy a stone as you want, firebricks, and the added benefit of the heat source being down there) but is by default lacking above (just the optional mini stone). Traditional WFOs have also got a bunch of insulation both above and below. Of course, they've also got a lot more space and a much less forgiving heat source, so a direct comparison isn't quite fair. The LBE is essentially completely without insulation (except for the couple with ceramic blankets added).
As such, one of the more common stumbling blocks seems to be effectively dialing things in so that the top gets heat commensurate with the bottom.
My question: Would there be a benefit to more closely mimicking the action of a traditional oven? My thought is to attempt to build a layer of insulation (either ceramic blanket or perlite/vermiculite-cement) and a layer of thermal mass (large stone or refractory mortar) into the lid of a 22" weber (I prefer a big pie). Have I got any chance? Or will it be just too tight? Can I get enough insulation in there to make a difference? I'm not really sure how much clearance I'll need in the end. Also I've got basically no experience with working with these things, so I'm really just completely guessing based on theory rather than practice.
I notice the pizzahacker design gets around the clearance issue by building up a spacer between the lid (in his case, a newly fabricated refractory cement and perlite lid) and the grill. That's an appealing possibility, as it's also an easy(-ish) way to make a vent/door through which to feed the pizzas. I'm curious what he used to build his replacement top from, as it seems like something like that plus all the great ideas here could work together quite well.
I feel like adding insulation and relying on more radiant heat from the top should lead to a more even, more fuel-efficient cooking device. But I do wonder if these steps would counteract the simple conductive/convective cooking power of the LBE. I guess it's just something that'll require testing after I get around to assembling a first attempt. Now if those folks from craigslist will just email me back...
Thanks for all the great ideas in this thread. Clearly, they've got me going.
