Need a little more information before could answer. Is the master bedroom 1st floor or is it higher? (2nd floor +). Is the attic directly above the room? How many and what type/size windows are in roo ... read more
Verify that all window and door seals/weatherstriping is in good shape.
Check to be sure doors and windows are caulked properly (no gaps, cracks or missing).
If you have an attic access, treat it like ... read more