Hello,

I'm renovating the finished basement in my house and when I remove the
drywall on the ceiling, I find it is attached to strips of aluminum
rather than to the joists directly. The AL strips are nailed directly
to the joists but are shaped to provide about 1/2 inch gap between the
joists and the drywall. Is this used to allow ventilation between the
joist bays? I can't imagine another reason. One other thing, as I
recall, all the AL strips run perpendicular to the joists, and are
also on some walls, horizontally.

Thanks,

Teabird