How to Shop for Mortise Locks

A mortise lock is specialty door hardware that is set into a deep pocket that has been cut into the edge of the door. Typically used in commercial applications, mortise locks are gaining popularity for residential use because of their superior strength and security.

How Mortise Locks Work

A typical cylinder lock is inserted through a hole bored into a door, and is only supported by door material itself. A mortise lock passes through a strong, metal chassis that has been inserted several inches into the side of the door. This reinforced design can protect against forced entry.

Mortise locks have more intricate internal mechanisms than standard deadbolts, making them nearly impossible to pick.

Mortise Hardware Types

As with all door hardware, there are different types and terms for the different functions of the mortise lock.

• Keyed Entry locks are used for exterior doors.
• Privacy locks are typically used for bathrooms and bedrooms.
• Dummy Sets are designed with the appearance of functioning mortise hardware, but have no inner workings or locking mechanisms.

Prepping the Door For A Mortise Lock

The internal workings of the mortise lock are contained in a large, metal case. A precisely-measured pocket must be cut into the side of the door to accept the case and boreholes are needed for the knob (or lever) and locking cylinder. Proper door preparation requires advanced woodworking skills and specialty tools. Consider hiring a professional for new mortise hardware installation.

Configuring Your Hardware

Once you’ve chosen the style and finish for your mortise set, you’ll be asked to choose the correct specifications for your application.

If Trim Set Only is chosen, no cylinder or mortise box will be included. A trim set is not a dummy set and it is assumed that you already have the mortise box and cylinder, or will be purchasing them separately.

TIP: When replacing a mortise lock, choose new hardware with the same measurements and configuration to avoid having to drill new holes in the door.

Measure the thickness of the door and select the mortise box and cylinder specifically designed for that measurement.

Handing refers the the side from which a door opens. While some door hardware has reversible handing, many are appropriate only for right- or left-side installation. To determine which handing you have, face the door from the outside of the room; whichever side the hinges are on is the handing.

Choose from a variety of a knob or lever Handle Styles.

Backset is the measurement between the edge of the door and the center of the hole for the knob or lever.