JimB wrote:
Most of the textured finish and tape is peeling from the ceiling and
walls of my two-car attached garage. The standard interior drywall was
not primed or prepped, nail heads are rusty. My plan is to scrape off
the loose texture and sand off the area still adhered, re-tape the
joints and apply a coat of paint primer before a finish coat of
exterior latex. Any suggestions different from the plan or
recommendations for materials?

go here and read up:
http://drywallschool.com/