A trap door is a door placed on a horizontal level, either on a floor or in a ceiling. There are many different types of trap doors, and although the most common variety hinges on two hinges like a normal door on its side, they may also be on some sort of sliding mechanism. The most common type of trap door is that found leading to the attic space in a house, but in most people’s imaginations a trap door leads to somewhere secret.
In some houses, a trap door may be installed to lead down into a basement, especially a smaller basement area. Often the trap door will lead to a very small storage space under the main floor, sometimes referred to as a smuggler’s hole. This type of trap door is commonly seen in movies and in novels, especially those set in a historical era. In this case, the trap door in question is often hidden beneath a rug or piece of furniture, and acts as a way of concealing a secret chamber, which may be used to store illicit goods, or to hide people.
In the theatre, a trap door may be installed to allow actors or performers to vanish from the stage, either visibly or invisibly. In many illusions, for example, a magician may use a trap door to allow either themselves or a performer to vanish quickly while concealed behind or inside of something. In plays, a trap door may act as a simple way for an actor to remove themselves from a scene without having to exit through one of the wings. Generally, a trap door will lead either to a recess beneath the stage, or down into the orchestra pit. Traditionally, a trap door would have a slight drop beneath it, so that a person could simply leap down, but some modern trap door designs have hydraulic lifters built in, so that people and set pieces may be lowered or raised to the stage seamlessly.
These exotic uses aside, however, the trap door is most often seen when a high space needs an access point, but does not necessitate a landing or stairs. Attics, for example, often have a trap door leading to them, either with a retractable ladder, or simply a space where a ladder can be brought over. Some rooftops also have a trap door access, allowing people to get from the interior to the roof to work on things, without having to climb up a ladder on the outside of the building. Ultimately, a trap door can be placed anywhere an access point is needed in either a floor or ceiling, as their horizontal alignment allows them to take up very little room, and remain completely out of the way until they need to be used.