If you need building inspections, you can go up to 10' with 2x4 walls 16" o.c. If you go higher, you will have to do 2x6 walls or double up the 2x4 studs. I used 10' studs in my garage on a 6" stem wall for a roughly 10'9" ceiling height. Studs were precut to 117" I believe to account for...