Both myself & my brother put up our buildings ourselves. I had my 40x60 concrete done & we poured my brothers 30x40.
Love our shops. Now some items of note.
1. If you removed a tree stump, compact it every 6 inches during dirt fill. They compacted mine with a trac skid steer & you ddont get the compation due to the tracks spread out its weight. Weeks after a cavity developed at the edge of the slab. Dug it out 6 feet & compacted every 6". Pics coming soon.
2. If you have trees forget gutters unless you like a garden 12' up in the air.
Put down rocks in the drip line. Stops dirt from building up on the siding from the rain.
4. Measure twice & pour once! One of my anchor bolting for a column was 1 1/2" off.. I noticed it after the main beams was errected & my holes in the purlins started not matching up.. (jacked up the column, drilled the concrete 6" to bent the anchor bolts a little & slotted the base plate. Worked oerfect.whew!
5 the corregated roll up doors have a Lot of air leakage if you are AC cooling. Conventional roll up panel doors seal better. Just somthing to think about.
6. Flat or sloped concrete floor. Your choice. Jut note... Flat is not 100% flat. Mine isn't and when I wash down after a dirty task some water wants to run under the cabinets.
7. Car port? My 40x60 shop is actually 40x40 with a 20' extension for a carport. LOVE my carport area. I do a lot of stuff out there.