What is the recommended gap from the bottom of an interior door to the floor, to ensure proper airflow into a room?

Asked by Toby Broemmeling
Spokane, WA

We are installing interior doors and are curious how much gap we should leave.


Allowing a gap at the bottom of a door cannot support proper airflow.

Each room except for bathrooms and kitchens should be equipped with its own cold air return duct for proper heating and cooling distribution.

  • If a room is not equipped with a cold air return, it should then have a transfer air grill installed between the room and adjacent hallway which may already have a cold air return duct installed.
  • However the drawback to this method of providing air distribution is that it allows noise to freely move from one space to the other creating an undesirable effect.

If possible, install a cold air return grill within each room on an interior wall, located high on the wall and across from the supply duct for increased efficiency.


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