and a little off track because I know your sister isn't going
the foamed roofline route..but
the foamed ductwork route...I'd still opt for the roofline
and address house to attic leakage over the foaming of
ductwork. with studies like this people are doing their best work.
hiring a foam company to do duct sealing as proposed in study
would entail some education and not just spraying an going.
the problems with foaming ducts are just what the study shows
poor air sealing & adhesion issues.
just my pov