I just finished this a few onths ago. I did a real time build along on a few sites during the time it took to construct. I am copying it here by request.
My last homemade smoker lasted 15 years. It was a converted chest freezer I tipped on its side and it worked great for hot smoking but eventually rusted through because of the heat and moisture and salt inherent to the smoking process.
Being that I like to build things, I began building a new smoker from scratch. I searched online for big electric smokers to get a feel for what’s available and to find something to pattern mine after (never been ashamed to steal a good idea) Most of the smokers were too small for what I want but none of the big commercial units allowed for cold smoking. Part of the reason I want a new smoker is so I can smoke things like cheese, nuts, lox and other things that are cold smoked. Also the big commercial units cost around $4,000. I think the price is fair considering what you get but I would rather make my own.
This is an example of what out there.http://store.cookshack.com/p-121-smarts ... sm160.aspx
I like it but it cant be used to cold smoke and it has too few racks. My smoker will sit outside year round so it has to be weatherproof. Since most of the meat smoking I do is in the winter in temps below freezing, I will insulate the smoker with 1 ½ thick foam board. I will use treated lumber for the legs since its going to sit outside year round. I will make it for hot smoking but will build a cold smoking adapter. I want ten racks and the extra height for smoking hot sticks and bacon sides. The inside smoking area I’m shooting for is 25” wide, 20” deep and 48” tall and will be lined with aliminum. Its going to have dual exhaust, and T-111 exterior siding and will be about 7 feet tall. The inner walls are going to be ½ inch thick plywood.
The back wall
Fast forward to the completion of the structure. The upper opening is the smoking chamber. The lower is where the electric heating elements and pan filled with wood will go. each compartment will have its own door so I can add wood and adjust the heat without opening the upper area and letting all the heat out. The recessed areas are 1 ½ inches deep and will be filled with pink foam board (R-7.5).
Here is the inner ceiling. I’m using 3 inch galvanized for the smoke stacks. I cut and bent tabs all the way around to attach it to the wood and to have a good seal.
Testing to see if it fits.
The space between the inner ceiling and the outer roof will be filled with insulation board. This was to test the fit to make sure I had the smoke stack holes in the right place.
I don’t have a sheet metal break for making the bends in the aluminum lining so I improvised.
The floor piece being tested for proper fit. My plan is to wrap all the exposed wood with aluminum. I will use aluminum nails to hold the aluminum lining in place to avoid rust.
The racks for smoking will be supported by 3/4 inch poplar dowels. They will be supported by the hard maple strips on each side. I drilled a 7/8 inch hole about halfway through the maple and then split each one on my table saw. Each strip will be able to support 5 dowels.
Once I finish lining the entire inside with aluminum, I will attach the maple rack supports.