One thing to remember about the advice on that site, its for sound proofing to use the space for practising drums. :shock:
Our youngest son is a drummer, practise is very loud and repetitive. :?
The last drummer we had in the Ceilidh Band would delight in popping the sound limiter found in some venues, before I had even plugged the PA in. :roll:
So the measures are probably more than the average workshop needs.