I would do 10' with 2x6's as studs. The "extra" cost will not
even be noticed and that extra room in the wall can be super
insulated. Super strong and roomy. I have 12' ceiling and that
is excellent. I truly regret not using 2x6's when I had the
chance.

Brian Elfert wrote:

I'm in the planning stages for my shop building. My initial plans called
for 9' walls with a vaulted ceiling so I would have plenty of overhead
clearance.

Are 9' walls still enough clearance if I switch to a flat ceiling? Are
10' walls really worth all the extra lumber and heating/cooling expense?

In an ideal world, the walls would be 12 to 15 feet high, but I don't have
the budget for that.

Brian Elfert