It's a HUGE difference between a coal oven and a WFO. It's not just airflow below the coal grates; it's FORCED airflow. The entire fire management process is completely different too. Almost zero similarities.
Awesome info, thank you. I didn't realize the differences between coal fired ovens and WFO. I also realized, in the past hour, that I should have clarified between coal fired and lump charcoal fired, which it seems Andrew is using and I probably would use. I can see how forced airflow would be important with coal, and I wonder if this would be important for lump charcoal. With lump charcoal being wood, I feel that it could be used directly on the deck as in a wood fired oven. So why did Andrew put it on grates? I wonder if it was just for increased airflow or just ash management.
I can't help with most of your questions. I can tell you that under my oven stand there is about a foot of compacted crusher run stone and the a concrete slab. My stand is already overkill. Footings below the frost line seemed really overkill since I was on well compacted sand.
For the roof, if you are building in Massachusetts, I would recommend having a slope to the roof. You want any rain or snow to flow off. A flat roof can pond and if it leaks, it will ruin your insulation. You can build a structure around the oven or put on a tin roof or build a shelter around the oven. You can look around at different oven structures and find something you like.
One other thing, I'm not into the lingo of coal ovens. When you say lump charcoal I think wood burnt down to coal for grilling. I'm assuming you are thinking coal like mined coal. Anthracite I think. No experience with it, but I've watched that Forged in Fire show and when they use coal, airflow is very important.
You are not too far from a few Pepe's locations. Might be worth getting a good look at one of those ovens for research...and a pizza.
Awesome info too, thank you! My goal is really to replicate the Pizzeria Regina coal/gas fired oven in the North End of Boston. Of course, I wouldn't do gas, so I wanted to go back to how PR used coal, but probably use lump charcoal instead. I've had awesome results using lump in my Uuni Pro, but I wanted a bigger oven to do 22" pizzas. I'll have to decide on whether or not I do a grate system for the lump charcoal or just burn it right on the deck.
The stone and concrete slab are similar to what is recommended in the book "Bread Earth and Fire": Earth Ovens and Artisan Breads
By Stuart Silverstein. He recommends filling with gravel, rocks, and rubble, followed by 10" of dry medium perlite, and on top of that 2 inches of a mix of perlite and Portland cement. He places solid concrete blocks on top of that, and then firebricks on top of the blocks. I was surprised to read that there is no need to mortar between the concrete blocks that make up the walls, and that he stuccos the four walls with surface bonding cement. Overkill is always good.
My idea is to make this base pretty big, and then make the firebrick the entire inside of the blocks. Then I'd build around the firebrick. I'll make a mockup. I was debating using coal, but the health concerns are not worth it. A slope is an awesome idea, and I have a mason friend who is going to help, so I won't be going in alone. For the roof, what is the typical materials if not making a mud and perlite dome? Could you do it with just bricks? Andrew's looked like this, but I couldn't tell.
The concrete ground slab is about 6 ft x 5 ft. also.
I definitely will visit Pepes and maybe even the CT location, if not the MA ones. Thank you for the recommendation. We have a bunch of coal fired places around me, but I always look for the original. Pizzeria Regina was even coal fired back then I believe. The oven design I'm thinking is similar to Pepes, with a fire door on the right and a main door in the middle. I may try to replicate this two door setup, just for emptying out and adding charcoal.
https://pepespizzeria.com/photos-by-tom-mcgovern-2/
