What type of lock function do you need?
Your security and durability requirements will determine the type of door hardware you buy. The style of trim (knob, lever, or thumbgrip handle) is irrelevant at this stage—what matters is the lock function. Here are the most common configurations:
For exterior doors
- Mortise locks: All-in-one locks that are encased in a rectangular metal box for extra security and durability. Mortise locks are often used in entry doors and include deadbolts.
Keyed entry: These knob or lever latchsets incorporate a key-operated lock within the latch mechanism. When used on entry doors, keyed entry sets are often used together with auxiliary deadbolts.
- Passage: These knob or lever latchsets have no locking function; think of them as the plain-vanilla of interior door hardware.
Privacy: Knob or lever latchsets that can be locked, often with a simple button lock or push-and-turn lock. Used where a light-duty lock is needed, such as on bed or bath doors.
These are knobs, levers, or handles that are not connected to any latch or lock mechanism. They serve only as matching trim in a double door setup (such as with French doors).
What is the backset?
For doors with pre-drilled holes or existing door hardware, you need to measure the backset, or distance between the edge of the door and the center of the hole. Standard residential doors usually have either a 2-3/8” or 2¾” backset. Knobsandhardware.com offers a search function by which you can easily find all the products that fit your backset measurement.
What is the stile width?
A stile is the outside, vertical part of a frame-and-panel door where the knob or lever is mounted. There are several reasons to measure stile width:
- • The backset of the lock is determined by the stile width, since it is aesthetically pleasing for knobs, pulls, or levers are mounted in the middle of the stile.
• If the door hardware requires too deep a preparation depth (edge bore), you may not be able to install it on a door with a thin stile.
• A thin stile could impede knob operation (and cause scraped knuckles!).
• For push plates and pull bars, stile width must exceed the width of the mounting plate.
What is the hand-of-door?
Also known as door handedness, the hand-of-door refers to the side with hinges (when viewed from the outside of the door). Most residential doors are left-handed and swing inwards, but closet doors and storm doors swing outwards (which is called reverse left-handed). You need to specify hand-of-door when buying non-reversible door hardware such as heavy-duty mortise locks and sets where a thumbgrip handle is used on the outside and a lever on the interior. Hand-of-door should not be confused with hand-of-lever, which applies only to half-dummy applications. For single (half-dummy) levers, handedness is always determined by the direction in which the lever points.
What is the door thickness?
Residential interior doors are usually 1-3/8” thick, while residential exterior doors are usually 1¾” thick. If your doors are outside those measurements, please pay special attention when purchasing door hardware. Sometimes there are conversion parts available for special thicknesses.
What material is the door made from?
Door hardware vendors assume wood construction unless hollow metal, metal-clad, or glass is specified. Materials other than wood require different fasteners.
Is there a pre-drilled cut-out or existing door hardware?
The majority of doors sold at retail outlets have 2-1/8” cut-outs to facilitate door hardware installation. If you have a pre-drilled cut-out or existing door hardware, you need to measure the diameter of the holes (and distances between holes, in some cases) and make sure the door hardware trim (knob/lever rose or escutcheon plate) covers the openings. Some door hardware sets are especially for pre-drilled doors while others are made for custom installation.
What is the center-to-center distance?
For door hardware, center-to-center usually refers to the distance between the center of the deadbolt and the center of the knob/lever. This distance is critical for latchsets with an auxiliary deadbolt because crowding could cause problems with installation and function.
Does your door have glass windows?
For entry doors with glass windows or doors set next to glass windows (sidelights), a double cylinder deadbolt (keyed operation on both sides) can add security since burglars do not have an inside thumbturn with which to unlock the door. On the other hand, a double cylinder deadbolt is restricted by fire code in some jurisdictions.