Replacing a patio door mortise lock: what the door makers say

The short answer

BHMA, the Builders Hardware Manufacturers Association, defines a mortise lock in its terminology guide as "a lock fitting a rectangular shaped cavity in the edge of a door." JELD-WEN's wood patio door guide describes its single-point sliding door lock the same way: a lock assembly held by attachment screws in the door edge. None of the makers' documents opened for this page uses the word "mortise"; they say lock assembly, reachout lock, or lock mechanism.

Whether you can replace one yourself depends on the maker. JELD-WEN's wood door guide and Andersen's guides give replacement steps, and both JELD-WEN patio door guides end with this note:

"The repair tasks offered herein can be accomplished by a homeowner with some mechanical aptitude. If you are unsure, it is recommended that you hire a trained service provider such as a competent and licensed construction contractor or building professional."

Pella's owner's manual gives no lock replacement steps, and says all service adjustments to Pella hinged doors should be performed by a professional. With every maker, the first job is identifying the right lock. JELD-WEN says locking mechanisms have changed over time and can be very complex.

Every statement here comes from documents opened on November 4, 2026 and linked at the bottom. This site is not affiliated with any maker.

Mortise lock vs. cylindrical lock

BHMA separates the two by where the lock body goes. A mortise lock sits in a rectangular pocket in the door's edge, and a round hole in the face takes the spindle for the knobs or levers. If it is key operated, a second round hole above takes the cylinder and thumbturn. BHMA's entry for a bored dead lock, which it says is also called cylindrical or tubular, describes locks fitting round holes bored in the face and edge of the door. The face hole, usually 2 1/8 inches across, holds the lock body, and the edge hole, 7/8 inch to 1 inch, holds the latch bolt.

Two more BHMA terms help. Backset is the distance from the edge of the door to the centerline of the cylinder, at the centerline of the door's thickness. A strike is the plate on the door frame, or on the inactive leaf of a pair of doors, that the bolts project into; patio door makers also say keeper or receiver.

BHMA's glossary does not mention patio doors. It says its types-of-locks terms are covered by ANSI/BHMA standards A156.2, A156.5, A156.12, and A156.13, which this page did not open.

The lock in a sliding patio door

In JELD-WEN's wood door guide, the single-point lock's attachment screws in the door edge are removed after the handles, the interior lock lever, and the exterior keyway lock come off. None of its lock steps lift the panel.

Andersen calls its sliding door lock a reachout lock: a hook that secures into the latch receiver on the second panel or the frame. Andersen says the deadlock on 200 and 400 Series doors made from 1978 to 1993 is outdated, and that gliding door deadlocks on units made from 1994 to 2005, and before 1994, can be upgraded to the current reachout lock and receiver.

The lock in a hinged patio door

Pella's manual says its Reserve and Architect Series hinged doors, and in its appendix the Designer Series and Pella 450 Series, have a multipoint locking system that engages at the top, middle, and bottom, plus a thumbturn lock and keylock. Andersen's replacement guide for its 200 Series hinged inswing door calls the part a multipoint lock mechanism, screwed into the door panel, and says to check the new lock's handing against the existing lock.

JELD-WEN's wood guide covers multi-point and single-point swinging door locks. Its handing check: hold the mechanism up to the active panel, and if the flat side of the latch faces the jamb, change the handing. On French Manor and French View doors, that takes a new astragal assembly from JELD-WEN.

Identify the lock before you order

• The maker and series. The maker label guide shows where each maker puts its label.
• The age of the door. Andersen's lock instructions are split by when the door was made. Andersen says most of its windows and patio doors have an etching on the glass, and that the etching includes the manufacturing date: when the door was made, or when a door panel was replaced.
• The handing. Andersen hands its gliding doors from outside: with the operating panel on the left, the unit is left-handed. On 100 Series gliding doors, Andersen says the locks are not handed. The XO or OX guide explains the labels.
• The part itself. JELD-WEN says to compare a replacement handle set or lock with your existing hardware, and to keep track of where each screw and part came from. Its vinyl guide notes that some locks are adjustable, with a lock hook adjustment screw, and some are not. A photograph of the lock face records what you have.

Before ordering, rule out adjustment: Andersen says locking hardware that does not engage properly may mean the door is slightly out of alignment, or that the handle set (trim set) needs replacing. The alignment page and the lock and handle page cover that.

Ordering a replacement

Andersen. The Andersen Parts Store sells trim sets for A-Series, 400, and 200 Series gliding doors, and Afton or Tulsa trim sets for 100 Series doors. For A-Series, 400, and 200 Series doors, the reachout lock and receiver kit is not included with the handle hardware. The 400 and 200 Series kit is sold through the Parts Store; for A-Series reachout locks, Andersen says to contact Andersen or a local retailer. For the 1978 to 1993 deadlock upgrade, a two-panel door takes the 2-Panel Reachout Lock and Receiver kit and a four-panel door the 4-Panel kit, and Andersen recommends replacing all the locking hardware with the current style.

JELD-WEN. For help identifying your lock type, JELD-WEN says to contact it. For multi-point handle sets, it says to follow the instructions included with the new handle set. Its vinyl guide has no lock replacement procedure; its troubleshooting table lists "Replace lock" for a damaged or broken lock.

What the makers say about doing it yourself

JELD-WEN calls its wood door guide's procedures common user serviceable repair tasks, and says to contact it for professional help with anything the guide does not cover. Andersen says that, depending on the concern, you can adjust the locking hardware, or replace the trim set or the reachout lock and receiver. Its gliding door hardware guide, which does not cover 100 Series doors, warns that incorrect installation may affect egress and home security, and that a misaligned lock button and latch receiver may result in loss of building security. Its hinged door guide gives the same home security warning, and asks that the guide be left with the homeowner.

What this site leaves to a professional

• Removing a panel. JELD-WEN's vinyl door guide marks operating panel removal "For Professionals Only." This site gives no steps for lifting or removing a panel.
• The roller steps in Andersen's hardware guide. Two steps in that guide, one for 2-panel doors and one for 4-panel doors, lift the operating panels to set the rollers. This site does not pass them on.

If you rent in Texas, the rental security device guide explains which sliding door locks the Texas Property Code requires and when the landlord repairs them.

What this page does not cover

• Prices. None of the documents opened for this page gives a price for a lock or for the labor to fit one.
• Other makers. This page covers Andersen, JELD-WEN, and Pella only. In a web search on November 4, 2026, no Marvin or Milgard lock replacement document turned up on those makers' own sites.

Asking about a lock

Use the contact page, with the maker and series if you know them and photographs of the label, the lock face, and the keeper. The operator reviews every inquiry and replies with the next step. Sending the form is not a booking.