The home is in south central PA. I believe the garage ceiling has at least r-19 and the attic r-30.
A visit to the home supply store had panels with r-factors of 3.0, 3.6 and 4.0.
Would adding r-3.0 panel to the garage ceiling
and r-4.0 panel to the attic bring the temperature variation to 5 degrees or less?
The home is 4 years old, two heat pumps with oil furnace back up for downstairs heat pump.
Heat pump is directly above the room, in the attic with three heat vents and one return.
Two walls to the room are interior walls, two are exterior walls. One exterior wall has a dormer window the other is at one end of the house. Tyvek wrapped exterior.
The other bedrooms and hallway temp at 69 degrees while the "cold" bedroom temps at 61 degrees.
The situation is reversed during the summer, the bedroom above the garage is much hotter than the other spaces on the second floor.