It will work, but you have to treat the roof as a psuedo
mobile setup, as it's not resonant. Well... Unless you
get lucky.
I'd just ohm out the roof and see if it's connected before
I started trying to bond it together.
The performance is semi iffy...
In general, radials that are resonant would be better, but
that assumes there are enough of them for a given height.
It's quite possible some bands may be fairly poor, if the
roof shows a high impedance. IE: much like trying to
use 1/2 wave long radials elevated...
MK