On Friday, June 5, 2015 at 12:55:42 PM UTC-4, HerHusband wrote:
I've never seen 2x4 trusses used for the bottom of the attic/ceiling
of the living space.

Trusses are almost always built with 2x4's, except for specialized trusses
like attic trusses.

Only problem is he said the attic has a floor and depending on how
much of it has floor, how many nails were used, etc., it could be
some trouble removing plywood to get the insulation in.

Did he mention an attic floor? I must have missed that.

IDK what WTF exactly he has, because the description hasn't
been clear. gravel roof? shingles? trusses? If you don't
have an attic, then how are you doing what he proposes,
unless you're tearing out the ceiling of the living space?