I have a 10'x12' garden shed, that is my air-curing barn. Leaf is strung on 17 gauge galv wire between the rafters, about 8-inches between strings. Mostly the burley strains, as they are generally ready to prime first.
Turkish strains are stung on wire, on a smaller wood frame, outside for sun-curing. This frame is small enough that it can be moved inside the shed on rainy days. I keep thinking it would be nice if I had a plastic cover that I could place over this turkish stringing frame, but never seem to get to it. Some day......
The bright leaf strains always seem to late-ripening, and the shed rafters are full of burley. Then, I use the stringing method, with cheap baling cord on 8 ft long wood 2x2's hung from the rafters.
I tried hanging in my attached garage one year. Temp and humidity was too low, and everything dried green.
Even though there are extremes in temperature and humidity throughout the summer months, the outside shed works best for me. Always seem to get a good cure. But, I do keep an ocsillating fan running on slow speed 24/7. My assumption, the fan deters mold, and the circulating air helps with the curing process, as sometimes, the green leaf is packed fairly tight.