In the 1500’s, people who could not afford to cover their home’s dirt floor were considered “dirt poor”. However, the wealthy had something covering the dirt, such as slate floors which would become slippery when wet. To prevent injury from the slippery floors, they spread thresh (straw) over the floor. The thresh would often move outside when the door was opened. Therefore, a piece of wood was placed on the floor in the entrance way, creating a “thresh hold.”
Today, threshold hardware has become more advanced than a piece of wood, but the purpose remains the same – “keep the outside OUT and keep the inside IN.”
There are three common commercial thresholds, each with a specific purpose:
1.) Saddle – The Saddle is the most common and basic threshold and is used in most entryways.
2.) Thermal Barrier – The Thermal Barrier is a piece of neoprene used to prevent heat/cold transfer under the door.
3.) Bumper – The Bumper threshold is installed to prevent water from entering. The difference in the design of the hardware can be noted in the below diagrams.
There are other types of thresholds available for special applications, such as ramp thresholds and floor plates. As noted in ADA code, thresholds over 1/2″ high on swinging doors are not allowed, and any slope greater than 1:2 does not follow the code. LaForce commonly supplies thresholds from Hager, Pemko, National Guard Products (NGP), Zero and Reese.