Hot/cold smoker and grill build

[verdammtertag]

Hello all -
Long time lurker, here and elsewhere, first time poster. I have been designing/dreaming about a multi-purpose outdoor cooker for a few years, and it's finally time to put it together. I am hoping to get some guidance on my design, and plan to post pictures of my progress though the build.


Design
The pit's design should allow for a few priorities:

• Cooking with wood - no part of this build considers alternative fuel sources like charcoal, propane, etc
• The ability to adjust the grill grate height, mid-cook without sacrificing a grill lid
• Hot smoke up to ~350 and cold smoke at, or below 90

Apologies, I am not (yet) proficient in SketchUp - this is a top down view

The red outline shows what is completed - a 48" x 48" x 28" brick square on a poured concrete footer. The open space in the outline is a planned open space and can reconsidered. For clarity, I labeled the following parts of the design:

1. Grill chamber - The circle is the middle section of a 22" WSM. I'm planning to remove the interior hardware, set it into a base of sand to level it, add a removable fire grate, and place the WSM drip pan into the bottom as a removable ash catcher. The other benefit of using the body of the WSM is I can also use the lid of the WSM. Haven't figured out the ideal setup for getting air into the chamber yet.
2. Grate height adjusters - This is still a little hair-brained, but I am considering casting a 2 in slab with a hole to set in the WSM. In each corner of the slab, I'd set in a hook to hold a link of steel coil chain that would run though an opening in the slab (thinking about setting in a little piece of pvc to ensure for easy slide), through a hole in the WSM body, and would hang the grate from it. In this way, I can ensure a tight fitting lid and grate adjustability when hot.
3. Fire box: Cold cmoker - Using Feldon's calc, a square firebox intended to maintain a small fire
4. Cold smoke passage - A thin-ish, 4 in metal tube connected to the back of the firebox, then routed into the external smoking chamber
5. Fire box: Hot smoker - Using Feldon's calc, a square firebox intended to maintain smoker temps of 225-325
6. Smoking chamber/chimney - A wooden box anchored to a base of cinder block with a stove pipe chimney

Here's the stuff I am looking for input on:

Fire boxes: I am not a skilled mason. Instead of the traditional fire brick interior for the fireboxes, I am planning to make molds and cast them from refractory concrete and mortar them to the concrete floor and brick wall. Any considerations here?

Grill airflow: Sort of at a loss here - I was going to go with boring out pluggable holes where the brick meets the body of the WSM, but I don't know if that's enough. Also considered adding some piping for intake at the base, but much of the rest of the design complicates that. Open to suggestions.

Adjustable grates: Any feedback here is useful. My solution feels overengineered, but I haven't been able to figure out a simple alternative

Hot smoker airflow: The current design uses a cinder block in the base of the smoking chamber turned on it's side (to expose the holes as pathways for air/heat) and mortared into the firebox as the opening. Two concerns here. First, is that enough of an opening? If not, should I plan to invert 2, OR should I cast the opening as apart of the firebox and mortar the cinder block base around it? Second, would it be useful to add a steel baffle at the base of the smoking chamber to evenly disperse heat?

Smoking chamber: I am going to build the smoker box from untreated wood and mechanically connect it to the base with anchor bolts set in mortar. I do not have any concerns about the temperatures in the chamber potentially igniting the wood - should I? To maintain temperatures, I planned to of course seal all of my gaps, and use a double walled box with an interior layer of rockwool. Is that overkill? If not, should I do the same thing in the roof?

I'll post pics as I work on the build - first up, pouring fire boxes!

 

[seenred]

That looks like an awesome project! I can't offer any insight - I've never even cooked on anything similar. But I'm looking forward to following your build progress!

Red

 

[netspyder]

having a hared time wrapping my head around what you have and what you're trying to accomplish. assuming your drawing is a top-down view ... you'll need some sort of draw to get the cold smoke through the pipe to the cook chamber. i'm assuming for cheeses/sausage/salmon/etc. means smokestack probably. not sure the lid of the weber would do that. for venting... an adjustable damper would be best... can rotate or slide... but if you're thinking holes in the masonry - less is more. you can always widen holes that aren't performing, but shrinking them isn't really a think that can happen. also, the air flow should be smooth... and by that i mean vent -> firebox -> cook chamber -> out... constant flow one direction... if you introduce more vents you'll only disrupt the flow of air (and smoke)

for adjusting the height for direct cooks - you have 2 choices - move the food or move the coals. might be a better plan to adjust the height of the coal pan rather than adjusting the height of the cooking grate. wander around the grill section of the box stores to get ideas on how this is done on the commercial cookers... then order those bits off amazon. many of those come with the handles for height adjustment when you order them online.