The door threshold originally referred to a board or a flat stone, wood, steel, or aluminum at the foot of the window frame of a door. In sacred buildings in particular, thresholds used to be significantly higher than they are today.
However, little has changed in terms of function since then: the threshold serves as a stop for the door leaf, prevents water from penetrating into the interior of the apartment and improves the insulation of the house.
What types of doorsteps are there?
Today the door threshold is flat, in the best case even barrier-free. It continues to cover the transition between different floor coverings and is often thermally separated for improved thermal protection. A fundamental distinction is made between so-called old building and new building thresholds.
Old building sleepers
This is a version without a floor recess. Old building sleepers are therefore not set into the ground, but placed on top. They serve primarily as a visual separation between different floor coverings and ensure a tight seal on the door.
New construction sleepers
In contrast, door sills in new buildings have a floor recess and in this way can also compensate for the height between the floor slab and the finished floor covering. In contrast to old building sleepers, there is a thermal separation of the different materials.
What do doors actually need a threshold for?
The most obvious use of a threshold is to separate different rooms, in front doors between inside and outside. However, the function is far more important than the appearance: Without a door threshold, there would be a gap between the door leaf and the floor through which heating heat could get outside and cold air could get inside.
A threshold closes this gap and thus ensures that the doors are optimally sealed. A prerequisite for this, however, is a corresponding seal on the lower door stop.
