It's so funny that you say that! Lol we were just at lowes the other day and my boyfriend said the same thing! I never knew it was an actual thing! Aha
LOL A building may make it a little easier and faster, those chicks grow up extremely fast and you will want them out pretty quickly too - they are dusty and get stinky.
Since you aren't going to free range - a lot of us don't, a generous run is very important. Go for 10sq. ft. for each bird - more is better. Think about the future as well. Either have adequate space for the ones you have now and have a plan for expanding later on or build big.