I’ve posted several photos and videos showing what happens when a bedroom door is kept closed during a fire. Check out this demonstration with the bedroom door open. The Estes Valley Fire Protection District conducted this test as part of UL’s Close Before You Doze public safety campaign. At the end of the test, the temperature at the bedroom ceiling is 379 degrees and the burn room is 978 degrees.
You can read more about this demonstration in the Estes Park Trail Gazette.