Geothermal a/c with air handlers in the attic. Metal roof with ridge vents. system is struggling to produce adequate a/c.
HVAC contractor believes the attic insulation is insufficient (system designed assuming R-38 on attic floor but R-30 was installed in error).
Builder is offering to put rigid insulation on attic floor and recover with plywood (so it would be R-30 fiberglass that is in the attic floor now covered with plywood, a sheet of rigid insultation, then another sheet of plywood). the reason they dont want to pull up the existing plywood and install R-38 is because they are worried about the stress this might put on the plaster ceilings below.
Q: would you do the above OR would you just get the spaces in the roof rafters sprayed with icenyne to get the attic temperatures down?