How to Replace and Repair an Interior Door Jamb and Casing

Replacing or repairing an interior door jamb and casing might seem like a daunting task, but it’s one of those home repairs that can be done easily with some basic tools and a little patience. Whether your door jamb is damaged, cracked, or just worn out from years of use, this guide will walk you through how to replace the damaged parts and get your door looking and working like new.

In this step-by-step blog, we’ll cover everything from removing the old jamb to installing the new casing and lock catch. If you’re dealing with a door that won’t close properly, a broken jamb or casing could be the culprit, so it’s a good idea to fix it sooner rather than later.

Tools and Materials You'll Need

Before we dive into the instructions, make sure you have the following tools and materials on hand:

Tools:

• Hammer

• Pry bar or crowbar

• Tape measure

• Level

• Utility knife

• Circular saw (optional, depending on the job)

• Drill

• Drill bits (for screws and lock catches)

• Brad nailer (or regular hammer and finishing nails)

• Carpenter’s square

• Multi-tool (oscillating tool)

• Clamps (for holding pieces in place)

Materials:

• 1x5 cedar boards (or other preferred wood for the casing)

• Stop molding (for the door catch)

• Wood glue

• Wood filler or wood putty (for gaps and holes)

• Caulk or silicone sealant (for sealing gaps)

• Paint or finish to match your room's style

Step 1: Removing the Old Jamb and Casing

The first step in replacing a door jamb and casing is removing the existing parts. This is where the bulk of the work comes in, as you’ll need to be careful not to damage the surrounding wall or trim.

1. Remove the Door: If the door is still in place, start by removing it. Unscrew the hinges from the door frame with a screwdriver. If the door is stuck or jammed, gently tap the hinge pins out with a hammer and nail set.

2. Cut the Seal: Before removing the casing, use a utility knife to cut the paint or caulk around the edges where the casing meets the wall. This will prevent the paint from peeling off the wall when you remove the casing. You want a clean break so that you don’t damage the wall’s paint or drywall.

3. Remove the Casing: Once the paint seal is cut, use a pry bar or crowbar to gently remove the casing. Start at the edges, working your way around the door frame. Be careful not to force the pry bar into the wall, as this can cause damage. If the casing is particularly tight, you may need to use a multi-tool to cut through any nails or screws that are holding it in place.

4. Remove the Jamb: Once the casing is removed, it's time to take out the door jamb. Depending on how the jamb is installed, you may need to cut through any nails or screws holding it to the wall. Use the pry bar to gently lift and remove the jamb, being cautious not to tear up the wall around it.

5. Clean the Area: Once the old casing and jamb are removed, you’ll likely find a lot of dust, debris, and possibly old nails or screws. Take the time to clean the area thoroughly. Use a vacuum or a dust brush to clean up the area, especially around the wall and the floor.

Step 2: Measuring and Cutting the New Jamb

Now that the old jamb and casing are out, it's time to measure and cut the new ones. This is a crucial step in ensuring that the new jamb fits perfectly into the space.

1. Measure the Door Frame: Using a tape measure, measure the height and width of the door frame. Be sure to measure the inside of the frame where the jamb will sit. You want your new jamb to fit snugly but also allow room for the door to swing open and close freely.

2. Cut the New Jamb: Once you have your measurements, cut your 1x5 cedar boards to the appropriate size. If you’re using pre-made jamb legs, you can skip this step, but if you're cutting your own, use a circular saw to make the cuts. You’ll want to make sure that the jamb fits flush against the wall and door frame.

3. Dry Fit the Jamb: Before nailing or securing the jamb in place, dry fit it into the frame. Hold the jamb up to the door frame and check to make sure the measurements are correct. Use a level to check the vertical and horizontal alignment. If needed, trim any edges or adjust the fit before securing the jamb.

Step 3: Installing the New Jamb

Once the new jamb is cut and ready to go, it’s time to install it. This step requires a bit of patience, but the results are worth it.

1. Attach the Jamb to the Frame: Begin by applying wood glue to the back of the jamb, where it will contact the door frame. Use clamps to hold the jamb in place and ensure that it’s aligned properly. While the glue sets, use brad nails or finish nails to secure the jamb to the door frame. Nail the jamb at several points along the edges, making sure it’s held securely in place.

2. Check for Level: After securing the jamb, use a level to double-check that it is perfectly vertical. Adjust the position as needed, then finish nailing the jamb in place. It’s important that the jamb is level to ensure the door operates properly.

3. Cutting the Top Jamb: If the top of the jamb is too long or uneven, measure and cut it to fit. Be sure the top piece is square and flush with the rest of the jamb. This is the most visible part of the door frame, so ensure it’s clean and tidy.

Step 4: Adding the Stop Molding

The next step is adding the stop molding. This is the small piece of trim that prevents the door from swinging too far inward and helps keep it aligned with the frame.

1. Cut the Stop Molding: Measure the height of the door jamb and cut the stop molding to size. You want it to cover the space where the door meets the jamb but not interfere with the door’s operation. Some stop moldings are pre-made, but if you're custom-making it, simply cut a strip of wood to the right size.

2. Attach the Stop Molding: Using a brad nailer or hammer and finishing nails, secure the stop molding along the sides of the door frame. Make sure it's aligned evenly along the entire height of the jamb. Once it's in place, check that it doesn't obstruct the door from closing properly.

Step 5: Installing the Lock Catch

The lock catch is a crucial part of the door’s functionality, as it keeps the door securely closed when it’s locked.

1. Measure and Mark the Catch Location: Measure where the catch will go in the door frame. Typically, this will be near the middle of the door. Mark the center point of the catch on the frame, then use a hole saw or spade bit to drill a hole for the catch mechanism.

2. Install the Catch: Once the hole is drilled, install the catch mechanism into the hole. It should fit snugly and be centered in the jamb. Use screws or nails to secure it in place.

3. Test the Door: After installing the catch, test the door to ensure it opens and closes properly. The door should latch securely when the catch is engaged, and the door should swing freely without obstruction.

Step 6: Finishing Touches

Now that the jamb and casing are installed, you’ll want to make sure everything looks polished and clean.

1. Fill Any Gaps: Use wood filler or caulk to fill any gaps or nail holes in the jamb and casing. This step will give your door frame a professional finish and make it look seamless. Allow the filler to dry before sanding it smooth.

2. Sand and Paint: Once the filler is dry, sand the surface smooth and paint the casing and jamb to match the rest of the room. Choose a paint or finish that matches your home’s interior decor and protects the wood.

3. Final Inspection: Do a final inspection of the door jamb and casing. Make sure everything is secure, level, and properly aligned. Open and close the door several times to ensure it operates smoothly.

Conclusion

Replacing or repairing an interior door jamb and casing is a project that many homeowners can tackle themselves. It requires some patience, basic tools, and a bit of skill, but the result is a door that not only looks great but also functions properly. By following this step-by-step guide, you’ll have a new, functional door frame in no time.

If you’ve been putting off replacing your damaged door jamb or casing, now is the time to take on this DIY project. It’s an affordable way to improve your home’s appearance and functionality. Plus, with the right tools and a little elbow grease, you’ll save money by doing it yourself instead of hiring a professional. So grab your tools, measure carefully, and enjoy the satisfaction of completing this home improvement project on your own!