Convert Crawl Space To Man Cave?
sound like a stupid question? – well, it’s coming from an even stupider person, so watch out! 
here’s the deal: we have an average sized ranch, with at least a 4′ high crawl space (could be taller…i haven’t measured it). the width/length is a decent size, it’s dry, and has some electric.
my teenage son wants to know if it can be converted into a "rock man cave" – a place where he and his band mates can practice. at first, i thought the idea was absolutely ridiculous, especially seeing as the ceiling height isn’t much more than 4′ – so, obviously, they wouldn’t be able to stand or walk around without hunching over (and that’s an understatement – all five of them are GIGANTIC!). .
but then, the more i thought about it, i started to change my mind!?! – because, they wouldn’t be standing or walking much anyway – as they always practice sitting down – even in professional studio space (yes, they’re the infamous 5 laziest musicians on the planet)…
but i know there will be other issues – as to what those all are, i’m not quite sure, but i’ve thought of a few: no windows (there’s probably venting down there, right?), radon gas (if we find that there isn’t any when we test, then would installing a radon gas detector solve the problem?. no heat – i guess since the heat comes from the pipes in the crawl space anyway, they could pump some into the crawl space itself, right? – or do they do that already? (stop laughing at me – yes i *am* a complete moron). flooring (i don’t know what’s down there – i don’t even know what they usually put down in a suburban crawl space – it’s definitely not dirt – there’s tons of plastic…covering dirt?! – or concrete? or insulation?
so, if it’s not possible to convert a crawl space into a living area, please tell me why. if it is possible, please give me any advice you can on how to get started/what needs to be checked or anything at all that you feel would be beneficial for me to know…
(oh, no worries – i’m far too stupid to do any of the work myself, lol…however, i have a couple friends that are quite decently skilled…but i don”t want to bug them until i’m fairly sure that this is even possible, lol – yes, i’d rather have you Y!A people laugh at me about my insane ideas!). 
thanks. 
"i’m far too stupid to do any of the work myself, lol"
I will keep this manipulative strategy in mind for the next time I need work done and I am too lazy to do it myself. "I am far to stupid to carry that sofa up three flights of stairs. However, you are brilliant and could easily discern the the safest path."
Obviously, there are safety concerns. But, it’s not like you are going to be giving public concerts or opening a store in the crawl space. Any "building codes" would be a gray area, just like it would be for any tree house or fort built by children in the woods.
My cousin had a small area like that which was converted into a small club room in his house. However, he didn’t bring more than two or three people in it at a time and did not play musical instruments in it. He also only used it during the ages of 9 to 14. Not sure how a building inspector is going to find out about the area or why one would care. It is your private property and not a public area.