Hi all:

Asked this before but didn't get a reply that specifically addressed
the question so I thought I'd try again.

I'm putting up fiberglass batts in a flat roof, i.e., the ceiling is
removed so I'm working inside the house. The roof joists are nominal
2 x 10's. The insulation that was there before had been pushed up
into the cavity between joists and the flanges on the faced batts was
stapled to the wide face of the joists, just above the lower edge of
the joists.

My instinct is to staple the flanges on the narrow edge of the joists,
overlapping flanges to create a more secure moisture barrier.

Is one way of doing the stapling better than the other? If so, how
come?

Thanks.

Tom Young