Ceiling height for recording space

So when is a ceiling height absolutely too low (phase issues with overheads, not high enough to create a "decent" sound) and, when is a ceiling height too high (reflections are too late/long, sounds like crap)? sounds like a pretty open question but surely there is a range that works, in particular for drumkits?

depends on the sound you like. Many would say that anything shorter than 15' is too short. Others (myself included) would say you can get away with standard 8' ceilings if you treat them right. But in general, I would say the higher the better, probably couldn't get too high with normal construction. Remember that you get approx 1ms of delay for every foot of sound travel. So a 30' ceiling will get you 50-60ms delay.... not a tremendous amount by any stretch.