this room has an aluminum roof and hardwood siding. All the heat hit the aluminum roof
Spray on expanding foam is best, paint on radiant barrier may work, blow in insulation in attic (cellulose or fiberglass) or put 12"x12" Styrofoam ceiling tiles on the ceiling, they look decent and not to expensive, installs with latex adhesive or staples. Good luck
The best method is with a spray on expanding foam insulation. It will stick to the ceiling and has a very good R Factor (how the construction industry measures the insulation factor). Any other method will involve building an interior ceiling or penetrating the roof, which will cause water damage.
CUT ACCESS HOLE I/S HOUSE BLOW FOAM, IF YOUR LAST NAME BILL GATES! TRY FIBERGLASS BLOW DYI @ HOME DEPOT OR ROCK WOOL EVEN CHEAPER VENTILATE THAT ROOF - SOFFIT - TO LET AIR IN ROOF, RIDGE, AIR HAWK, WHIRLI-BIRD, POWER FAN ( SOLAR ), GABLE VENT - TO LET IT OUT!!!!