No exact spec here. I'd say leave an inch or so clearance on the sides and an inch or two below, for air circ and ash fallout. As for the height I like to leave enough room to add a split without pulling the basket all the way out.
Or something like that.
BBQ is just smoke and beers!
Usually more beers than smoke.
I can't document it but I got a hunch that somewhere around 8% to 10% of your dimension all the way around the fire basket should be clear for circulation as a place to start. Somehow that just feels right.
The FB I just finished for Egor is 20 X 20 X 18 and it's got minimum 2 inch all the way around.
Your 28 inch would then translate to about 2-1/4" to 2-3/4" inch gap. And a little more gap underneath the fire basket to allow for the ash pan below the drop zone. fwiw
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)
I manipulated my basket by adding expanded metal to reduce the length available to the interior of the basket. I wanted a more compact hot area of coals that would lend itself to a cleaner burn of new logs I add. My box is 30 sq with the rails giving me 2 inches on the sides but my basket spacer keeps the fire 8 inches from the CC wall when I slide the basket full in and I have about 4 inches on the back side. With all that said I would suggest a basket that is not so deep that the coals will be nudging against the CC wall on the back end of the FB. I'm with S1 on the height, you'll want enough space to allow for easy feeding during the burn. jm2cw
If it can't be smoked .... try frying it. It that don't work, it's probably best just left alone
I usually make the front of the basket open and make the basket slide in and out of the fire box for easy loading. the sides and back have a 4" tall expanded metal lip to hold charcoal cus you're not gonna fill it up anyway. just use 2 chimneys or so.
stick to minimum 1/8" thickness 'cause most FB components get treated pretty rough…..
And on the eighth day God created barbecue …. because he DOES love us and he wants us to be happy.
Current smokers: Egor (trailered RF) and Easybake (tabletop pellet drive)