Builders typically use standard door-swing practices that have been in place for years when installing doors. When the swing varies from standard installations, it's typically to accommodate architectural design or for safety reasons.
Bed and Bath
The home-building industry is ruled by codes, but the International Residential Code doesn't have a requirement for swing direction. The rule of thumb is to hang interior doors to open into the room, not out into a hallway or other common area. This is to prevent doors being opened into a traffic path and possibly blocking or bumping into someone going by. Alternatively, when aging in place is a design consideration, bathroom doors may open out to prevent the door being blocked by someone who has fallen inside the room.
Garage Entry Doors
Garage-to-home entry doors may be an exception to the inward-swinging rule. Some builders have swing them inward to the garage instead of the home. The reasoning is safety related. If there's a fire or explosion in the garage, the outward-swinging door blocks damage to the interior of the home more effectively than an inward-swinging door.
Left or Right Swingers
The design of the room typically determines the left or right swing designation for doors. An inward-opening door should swing in the direction needed to provide adequate passage. If it bumps or blocks passage because of a wall, barrier or other object when you open it, such as a toilet or cabinet, the door should swing in the opposite direction.
Identify Your Door
To identify a left- or right-swing door, stand inside the door opening with your back against the hinges. If the door opens to your right, it's a right-hand swing door. If it opens to the left, it's a left-hand swing. When purchasing a door for any reason, the left- or right-hand distinction should be established first and the door ordered accordingly. If you realize after the door is installed that the door swing direction is wrong and prevents access to the room, or results in a cramped or blocked area, the swing direction can be changed if needed by modifying the door jamb, and sometimes the latch edge of the door, which is slightly beveled to reduce the gap when the door is closed.
Exterior doors traditionally are installed to open inward. This places the hinges on the inside of the door, preventing them from being accessed by criminals. The reasoning is somewhat valid, but most contemporary door hinges are thief resistant and can't be tampered with when exposed on the exterior of the door. Contradictions to inward-swinging exterior doors are common in areas with possible high winds and/or water penetration such as Florida, where many exterior doors swing outward. The outward orientation blocks water and wind better because the doorstop prevents the inward movement of the door. Other exceptions to inward-swinging exterior doors might include interior light switches or electrical controls that are covered by the door when it's open. When purchasing an exterior door, first determine which type of door you need for a particular installation, whether it's inward or outward swing. Local codes typically don't enforce directional exterior door swing, but check the codes before installation.