metal building ... pre-planning insight?
Make sure you consider flammability of all the materials you intend to use. Most insulation materials burn very rapidly. Paper backing on fiberglass burns, and all plastics and foams have very low ignition temperatures and are great fuel for lighting up your entire shop in just a minute or two. Drywall and mineral wool are the exception, so get an understanding of your comfort level with fire before making a final decision. Woodworking materials and processes are high risk for fire, so the code [NCBC 903.2.11.7] requires any woodworking shops >2,500 SF to have an automatic sprinkler.
Then make sure your building fabricator gives you clear details for how they plan or recommend insulation, drywall, and cladding. These complicate the envelope construction considerably and the building you get likely won't support any extra weights. They should already have all these details, so just ask. NC requires a thermal gap between metal skin and purlins these days, but you won't get that if you get an ag building.
Technically, any building used as a woodworking shop is required to have a permit. Agricultural buildings are strictly for farming, but metal building manufacturers often sell farm level buildings that don't meet any wind, seismic, or snow loads required (and expected in NC) by the code for occupied buildings. I recommend documenting a permitted structure intended for human occupation so they price the proper steel gauges and lateral resistance support. Obviously, this makes them cost a lot more, but their web sites often won't tell you that unless you ask.
Verify your insurance policy agrees with all these decisions or you won't be covered if it blows over or catches on fire (or worse).
The next level of analysis involves figuring out conditioning, condensation, and dew point strategies, since exposed metal thermal bridges will sweat a lot in winter depending on how you heat and cool. (Natural gas, for example, has very high water content.) Cooling equipment and ducts sweat all over everything in the summer. If humidity matters, most pre-manufactured buildings leak air like a sieve unless you specify an (expensive) air control layer that usually needs an additional substrate (plywood) for proper installation.
If you really aren't worried about fire, then check out pre-manufactured
wood buildings, often called "pole barns." They'll usually have 8x8 posts down each side, connected by a beam, with pre-manufactured light wood trusses set free span across the entirety for the roof. They can be surprisingly large but are usually a little cheaper than metal buildings. They make more sense for smaller buildings since they don't have to resist as much wind or snow load. And they are easier to insulate since you don't have the thermal conductivity/bridging of the steel. Wood columns actually resist fire a little better than steel ones, but wood trusses will burn in a minute.
Sorry this is long, and I don't mean to be a naysayer. I'm actually working on an agriculture building and a shop building project right now, but have been finding so many regrettable building decisions that lock buyers into buildings that are inflexible or insufficient for purpose. Just do your research and you'll be fine.
