Your biggest decision, and most complex engineering, is in the door, and depending on the type of door, the support of the structure for it. Outside of that, it is basically just another building.
Typically, the door companies provide some guidance and examples of engineered solutions to support the loads in different types of building construction, steel truss, pole building, stick built, etc...
If you spend a bit of time on the Schweiss, Hydroswing, etc... web sites, I think you will find them helpful.
Total agreement with this!
Find a building company that will interface with your local Building Dept., and your hangar door manufacturer. They should be able to discern the local codes, and send your plans to the municipality for approval. Don't let them start cutting metal before everyone has signed off that it meets local code.
With regard to a door, I went with a Schweiss Bi-Fold, with strap lift. Also, I would recommend having it set up for the remote opener, even if you are not going to use it. As there is extra structure that must be installed on the door frame, it is a project to retrofit if you decide in the future that you want remote control. Some other considerations:
1. Insulation - We built our hangars as a consortium of 14, and some chose not to insulate at all, some just the roof, and a few of us did everything (including the door). It is money well spent, as my hangar is warmer in the winter, cooler in the summer, and does not "sweat" on the inside.
2. Electrical - Decide how many plugs/lights that you will need, and then add about 20%. I installed 3 plugs on each of the three walls, and one on the ceiling for a retractable reel. People thought that I had lost my mind, but after 12 years many have seen that I was right! Also, have the electrical contractor wire up a box for a ceiling fan on the center beam. I found a surplus warehouse grade fan, and installed that. It circulates air which helps cool in the summer, and brings the heat back down in the winter. Also, when the humidity is high, it keeps the air moving, reducing condensation.
3. This may not be important in your area, but the local geology in my area is an issue. The soil in our area is clay, with rock about 12" below the surface. As such, the water does not perk into the ground very well. When I built my hangar, I sourced a vapor barrier similar to what is used in landfills. I contacted a company that does this for a living, and bought their scrap. The majority of the other 13 hangars have issues ranging from minor to "OMG" with moisture seeping up through the slab.
4. Apron - You will see some hangars with a slab that is only about half the width of the hangar out to the taxiway. Then they install angled fillets up to the full width. I did a full width apron, and it is much more utilitarian, especially when you are storing two planes, or trying to get your car in/out of the hangar with the planes in.
5. Skylights and Vents - My hangar is 43'x36'....I have (3) 4'x8' skylight panels in each half of the roof. Additionally, I installed (3) 2'x8' panels in the door. It is a cheap way to take advantage of nature's free light. On a bright full moon night, I get enough illumination to walk inside without turning my lights on.
Make sure you have at least 2 roof vents in a hangar that size. The reasons speak for themselves.
6. Floor Paint - Paint the floor with a good quality epoxy paint BEFORE you move in! Some of my buddies tried to do it in sections after moving in, and it just did not work out for a multitude of reasons. Prep the concrete well prior to painting. I pressure washed to get all the dust and residue off, acid cleaned, and then pressure washed again. 12 years later, not one chip and no bubbling of the paint. It is a given that you will get oil, paint, and debris on the floor. With a quality paint applied, this just cleans right off. In my case, it sure makes it easier to find that dropped washer which I seem to do frequently! Another bonus is that the light color of the floor reflects light adding to the brightness of the hangar.
I am sure that I have bored you enough with my advice. I made a few mistakes along the way, but overall am pretty happy with my abode.