Guide to Door Locks and Bolts
If you are unfamiliar with industry jargon and necessary specifications, choosing the right door hardware can be a daunting task. There are many different types of door hardware available; levers, knob sets, screen door hardware, mortise locks, deadbolt sets, and latches (to name a few). Most door hardware is designed so it can be installed by just about anyone. But, figuring out what you need may still be a bit tricky.
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 Use
Mortise Lock: 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 Sets: These knob or lever latch-sets incorporate a key-operated lock within the latch mechanism. When used on entry doors, keyed entry sets are often used together with auxiliary deadbolts for added security.
Double Cylinder: Usually, for entry doors with glass windows or doors sets next to glass windows (sidelights), a double cylinder deadbolt (which means it has keyed operation on both sides) can add security since there is no inside thumb-turn by which to unlock the door. But, double cylinder deadbolts are restricted by fire code in most jurisdictions.
For Interior Use
Passage: Knob or lever sets with no locking function.
Privacy: Knob or lever latch-sets 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 bedroom or bathroom doors.
Dummy Hardware: Dummy hardware is sometimes seen in both outdoor and indoor applications. They are knobs, levers, and handles that are totally non-functional. They are not connected to any latch or locking mechanism. They serve mostly as matching trim in a double door setup (such as with French doors).
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 2-3/4" backset.
Back Plate? If a back plate is mentioned, it usually refers to the piece of metal that appears to separate the knob or lever from the door.
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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.
Door Thickness: Residential interior doors are usually 1-3/8" thick, while residential exterior doors are usually 1-3/4" 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.
Handing or 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 thumb-grip 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.
Pre-Drilled: The majority of doors sold at retail outlets have 2-1/8" cutouts to facilitate door hardware installation. If you have a pre-drilled cutout 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 made especially for pre-drilled doors, while others are made for custom installation.
Handedness of Doors
Center-to-Center: 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 latch-sets with an auxiliary deadbolt because crowding could cause problems with installation and function.
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, so pay attention if your door is not wood.
Cylindrical / Privacy Sets: A cylindrical lock set usually fits into a pre-drilled door and is operated by inserting a key into the knob itself. The bolts on these lock sets do not usually extend more than a half-inch into the door frame, and are thus, not the securest of lock sets. But, they remain a popular and inexpensive option that is easy to install. They can be coupled with deadbolts or latches in order to add an extra element of security.
Mortise Lock Sets: Mortise locks are generally the most secure door lock available. Usually a mortise lock includes all the hardware in a single rectangular casing, that often times includes it’s own dead bolt. More than that, they are aesthetically pleasing and come in a variety of different options. All of them are easy to operate.
Deadbolts: A deadbolt is a fundamental piece of door hardware, if you are looking for security. It has a flat-ended bolt that extends a minimum one-inch into the door frame. A good deadbolt will have a low side profile, which helps prevent tampering. The most popular style is a single cylinder deadbolt, with a thumb turn latch.
Other Door Hardware
Screen and Storm Door Hardware: Usually, screen and storm door hardware is included with the purchase of the door. However,if yours has taken a bit of wear and tear, you would like higher quality hardware,or you would like something that looks a little better, there are plenty to choose from. Screen door hardware usually functions in a simple manner, and will almost never be anymore complicated to install than a passage set on a normal door would be.
Keyless Entry Sets: Keyless entry sets are getting increasingly popular. They are commonly used in rental and commercial applications, and are becoming more prevalent in the residential arena. Keyless options vary a lot depending on the brand, style, and price range you are looking at. Some are more complicated to install than others, but regardless,most of them offer fairly detailed instructions and spec sheets, which should make selecting the proper lock a bit easier. Keyless entry sets are convenient and secure,and work great for large families, shared houses (such as sororities and fraternities),or those who tend to lose their keys often. Keyless entry codes are great for allowing people you trust in while you're not at home (such as your dog walker or maid),and it can be changed often to keep your home secure.