Both door to and door of are used frequently.
Door to emphasizes the perspective that the door is the entranceway
to a place. According to The American Heritage Dictionary*, it
is "a means of approach or access: looking for the door to success."
Examples from the Collins COBUILD** online include:
open the door to job vacancies for anyone.
.thereby opening the door to a dialogue with the U.S.
.I slowly pushed open the door to the morgue.
.by a nod of the head then opened the door to the Rolls .
.The door to the locked room was open..
Door of emphasizes the idea that the door is part of the entire
room, not that it leads to any specific place.
Examples from the Collins COBUILD online include:
Eve the door of my cell opened and the.
.when meeting a person, the front door of a house emits instant.
.packed into an old car at the back door of Number Ten Downing Street.
.himself up, reached the massive door of the barn and pushed. It.
She closed the door of her locker, then hit it.
It's possible that door
to and door of can be used almost
interchangeably; for example, you might say either
The door to the kitchen
is painted blue.
The door of the kitchen is painted blue.
You would choose to if
you are focusing on where the door leads, but of if you
are focusing on the appearance of the entire kitchen, including
This difference in emphasis can be seen in these two sentences
from the Collins COBUILD:
. jumped up and rushed over when the door to the
inner office opened.
Derek fled through the front door of the office.
In sentence (a), the perspective is that of going into the office, from
another place, so door to is used. In sentence (b), Derek is going
the other way, out of the office, and the door is perceived as part of
that office, so door of is used.
*The American Heritage Dictionary of the English Language. Houghton
** The Collins Wordbanks Online. http://titania.cobuild.collins.co.uk/cgi-bin/democonc