The backset of a door is a crucial measurement used when installing or replacing door hardware.
Understanding Door Backset
According to the provided reference, the door backset is defined as the distance from the edge of the door to the center of the 2-1/8-inch bore hole for the door knob, lever or deadbolt.
This measurement determines how far the door knob, lever, or deadbolt cylinder is positioned from the side edge of the door. Getting the backset right is essential for the hardware to fit correctly and function properly within the door jamb strike plate.
Common Backset Sizes
In the United States, there are two standard backsets commonly found in residential door locks:
- 2-3/8 inches
- 2-3/4 inches
Most residential doors are prepped with one of these two bore hole distances from the edge. Ensuring your replacement hardware matches the existing backset is vital for a smooth installation.
Why Backset Matters
Choosing the correct backset is important for several reasons:
- Proper Installation: Hardware designed for one backset will not fit correctly into a door prepped for a different backset.
- Functionality: The latch or deadbolt mechanism needs to align perfectly with the strike plate on the door frame. An incorrect backset prevents this alignment, making the lock inoperable.
- Aesthetics: While less critical than function, the backset also influences the look of the door hardware on the door face.
Here's a quick look at the common sizes:
| Backset Size | Common Use |
|---|---|
| 2-3/8 inches | Residential Interior/Exterior |
| 2-3/4 inches | Residential/Commercial |
Understanding the backset measurement is a key step in selecting the appropriate door hardware for your specific door preparation.
