guitarbassmetalhead

Sorry if this is in the wrong forum, I wasn't sure where to post it because this bass isn't built by me. Anyway, the problem is that often times there will be a weird buzzing noise that diminishes or disappears when I turn treble all the way down (on the bass, I've confirmed that it's something to do with my bass not my amp) or touch the strings or some other metal parts like the bridge or the metal near the output jack. The really weird thing is that, to the best of my knowledge, it only happens in buildings with a metal roof. It doesn't have any problems in my lessons, but whenever I play it at home or in church (both my house and church have a metal roof) the buzz happens. If anyone knows what might be going on any help would be appreciated.

What I plan on building is a guitar/5-string bass double neck, I have a pretty good idea of a lot of what I want, but especially on the wood I'm clueless, as I'm about as new to guitar building as you can get. As is obvious from my username, I play mostly metal but I want the flexibility to play other stuff with good tone. I'll give an idea of what I have in my head so far: Upper neck (guitar): 24 fret, very thin, going for a feel similar to high end Ibanez. Lower neck (bass): 24 fret, again, high end Ibanez type feel Guitar bridge: Floyd Rose Pro Bass bridge: haven't looked into this yet, feel free to make recommendations Guitar pickups: undecided, possibly EMG 81/85 Bass pickups: undecided, all I know is I want active pickups Keep in mind that I just started thinking about what I want beyond the basic guitar/bass double neck idea, hence the shortage of detail, all I'm sold on is thin 24 fret necks on both and a Floyd on the guitar. Any help will be appreciated.