When it comes to securing your home or office, choosing the right lock is one of the most important decisions you’ll make. While there are many types of locks available today, mortise locks are often preferred for their durability, strength, and timeless appeal. Whether you’re upgrading your current system or replacing an old, worn-out lock, this guide will walk you through everything you need to know about mortise lock installation & replacement.
Benefits of Mortise Locks
Before jumping into the installation process, it’s helpful to understand why many people choose mortise locks:
- Enhanced Security: Mortise locks offer better resistance against forced entry.
- Durability: Made from strong materials, they last for years, even in high-traffic areas.
- Versatility: Available in a range of styles, finishes, and functions.
- Aesthetic Value: The flush design often looks more elegant and classic.
Tools and Materials You’ll Need for Mortise Lock Installation & Replacement
Before you start the installation or replacement, make sure you have the following tools and materials:
Tools:
- Power drill and drill bits
- Chisel and hammer
- Screwdriver (Phillips and flathead)
- Tape measure
- Pencil or marker
- Mortise lock installation jig (optional but helpful)
- Wood filler (for repairs)
Materials:
- New mortise lockset
- Screws (usually included with the lock)
- Strike plate
- Faceplate (included with the lock)
- Door handles or knobs (if not included)
Step-by-Step Guide to Installing a New Mortise Lock
Step 1: Choose the Right Lock
Mortise locks come in various sizes and configurations. Be sure to measure the thickness of your door and check whether it opens inward or outward. Match the lock body and backset (distance from the door edge to the center of the knob) to your door specs.
Step 2: Mark the Mortise Cutout
Using the lock body as a template, trace its outline onto the edge of the door where you want the lock to sit. This will guide your drilling and chiseling.
Step 3: Drill the Pocket (Mortise)
Using a drill with a spade bit or a specialized mortise jig, drill a series of overlapping holes to the depth of the lock body. Be careful not to drill too deep or off-center.
Step 4: Chisel the Mortise
After drilling, use a chisel to clean up the hole and square the edges. Take your time—accuracy here is crucial to ensure the lock fits snugly.
Step 5: Fit the Lock Body
Slide the lock body into the mortise cutout. If it fits tightly and sits flush with the door edge, you’re on the right track. If it doesn’t, carefully adjust the mortise with your chisel.
Step 6: Mark and Cut for the Faceplate
With the lock body in place, mark around the faceplate. Then remove the lock and chisel a shallow recess so the faceplate can sit flush with the door edge.
Step 7: Install the Lock Body and Faceplate
Secure the lock body with screws. Then attach the faceplate using the smaller screws provided. Make sure everything is flush and level.
Step 8: Install the Trim (Handles/Knobs)
Install the trim pieces—door knobs, levers, escutcheons—on both sides of the door. These usually connect through the lock body via a spindle or threaded posts.
Step 9: Attach the Strike Plate
Close the door and mark where the latch and deadbolt hit the door frame. Then chisel a recess in the frame for the strike plate and secure it with screws.
Step 10: Test the Lock
Turn the key and handles to make sure the latch and deadbolt operate smoothly. If there’s resistance, check alignment and adjust as needed.
Also Read: What to Do If Your Key Breaks in the Lock
How to Replace an Old Mortise Lock
Replacing a mortise lock is usually easier than a new installation because the mortise pocket already exists. However, you still need to make sure the new lock matches the old one in size and backset.
Step 1: Remove the Old Lock
Start by unscrewing the faceplate and trim. Gently pull the lock body out of the door. Be sure to remove all screws and hardware.
Step 2: Clean and Inspect the Mortise
Check the mortise pocket for damage or debris. Clean it out and make any necessary repairs using wood filler or a chisel.
Step 3: Fit the New Lock
Slide the new lock into the mortise. If it’s slightly larger or smaller, adjust the mortise carefully with a chisel or file.
Step 4: Install the New Faceplate and Trim
Attach the new faceplate and ensure it sits flush. Then install the door handles or knobs on both sides.
Step 5: Replace or Adjust the Strike Plate
You may need to replace or adjust the strike plate to match the new lock’s latch and deadbolt positions. Use a chisel to modify the recess if needed.
Step 6: Test the Lock
Make sure everything functions smoothly, locks, latches, and handles. If something feels off, realign and tighten the components.
Common Mistakes to Avoid
- Rushing the mortise cut: Take your time to avoid an oversized or uneven pocket.
- Incorrect measurements: Double-check door thickness and lock dimensions.
- Using the wrong tools: A proper chisel and drill bit make a big difference.
- Forgetting the strike plate: A misaligned strike plate can stop your lock from functioning.
- Not testing the lock: Always test before calling the job done.
Need Help With Mortise Lock Installation & Replacement?
If you’re struggling with installing or replacing a mortise lock, don’t stress. Let the experts handle it. Contact The NYC Locksmith for fast, reliable, and professional lock services. We’re here to ensure your property stays secure with the best workmanship and trusted solutions.