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How to Fit a Rim Lock

Table of Contents

• Introduction
• Choosing the Correct Rim Lock
• Removing Old Door Hardware
• Filling and Sanding
• Positioning the Rim Lock
• Choosing the Correct Kind of Door Knob
• Fitting the Door Knob to the Rim Lock
• Disassembly, Painting, and Reassembly
• Related Rim Lock Blog Posts
• FAQ
• Handy External Links

Helpful Tips from the Video

1. Remove Old Ironmongery: Use a power drill to remove old handles, knobs, latches or locks.
2. Prepare the Door: Sand and fill any holes or rough spots on the door.
3. Choose and Mark the Rim Lock: Choose a suitable rim lock, position it on the door and mark the outline.
4. Install the Rim Lock: Drill pilot holes and install the rim lock with screws.
5. Measure and Install the Striker Plate: Measure for the striker plate, mark its position and install it.
6. Drill the Hole for the Mortice Bar: Measure and drill a hole for the mortice bar.
7. Install the Rose Plate: Measure, mark and install the rose plate.
8. Paint the Door: Apply primer and paint to the door, then allow it to dry fully.
9. Reassemble the Rim Lock: Reassemble the rim lock using the finishing screws.
10. Install the Door Knob: Install the door knob, ensuring the grub screw is tightened on the flat side of the mortice bar.

Introduction

If you've got an old door that needs a fresh touch, or a new door waiting to be made functional, fitting a rim lock is an excellent project to take on. Don't worry—it's not as difficult as it might seem.

This guide takes you through the process step by step. We'll begin by choosing the correct rim lock for your door before showing you how to remove the existing hardware.

Next, we'll cover preparing the door by filling and sanding any old holes, positioning the new rim lock, fitting the striker plate and installing your door knobs.

Finally, we'll look at painting the door before carrying out the final installation, leaving you with a traditional rim lock that's both practical and in keeping with your property.

Choosing the Correct Rim Lock

The first step is choosing the correct rim lock. Rather than simply picking the first one you see, there are a few important factors to consider.

First, think about whether you need a handed rim lock. These are manufactured specifically for either left-handed or right-handed doors. The key is to choose a lock that matches the direction your door opens.

If you're unsure which handing you need, our Rim Lock Handing Guide explains how to identify the correct version.

Next, consider how you want the door to lock. For bedrooms or bathrooms, you may prefer a traditional key-operated lock for additional security. Alternatively, many rim locks are available with a sliding bolt, often called a snib, which allows the door to be locked from the inside without using a key.

Finally, choose a style that suits your property. Rim locks are available in a wide variety of sizes, finishes and materials, making it easy to match both traditional and contemporary interiors.

Whether you're looking for a polished brass finish or something more understated, selecting the right rim lock will help create a finished installation that looks appropriate for your home.

Removing Old Door Hardware

With your rim lock selected, it's time to prepare the door by removing the existing hardware. In this example we're replacing a lever-on-backplate bathroom handle, but the same principles apply to most door furniture.

Begin by removing the turn-and-release mechanism. This is usually secured by a small grub screw located on the release side. Loosen the grub screw with the correct Allen key before removing both parts of the thumb turn.

Next, remove the door handles by undoing the fixing screws on each backplate. Once both handles have been removed, withdraw the mortice bar that connects them through the door.

The next component to remove is the sash lock. This is usually held in place by two screws on the edge of the door. Once these have been removed, the lock body should slide out without difficulty.

Finally, remove the striker plate from the door frame. This is the metal plate that receives the latch or lock bolt when the door is closed and is typically secured with two screws.

With all the old ironmongery removed, you'll have a clean starting point for fitting your new rim lock. Before installation, however, it's worth taking a little time to fill and sand any holes left behind to achieve the best possible finish.

Filling and Sanding

With the old hardware removed, it's time to prepare the door for its new ironmongery. Start by dealing with any marks or raised areas left by the previous fixings.

These small protrusions can usually be removed with a drill before sanding the surface flush with the surrounding timber. Taking the time to prepare the door properly will give the new hardware a much neater finish.

The cavity left by the old sash lock will usually require a two-part filler. This type of filler is ideal because it cures quickly and is designed to fill larger voids without shrinking.

To prepare it, mix approximately a golf ball-sized amount of filler with a pea-sized amount of hardener. Be aware that warmer temperatures reduce the working time, so it's often better to mix smaller batches during hot weather.

One useful tip is to avoid overfilling the cavity. Once cured, two-part filler becomes extremely hard, making it much more difficult to sand back. Filling only to the level of the surrounding timber will save both time and effort.

Allow the filler to cure fully before sanding it flush with the surface of the door. Good preparation at this stage makes the remaining installation much easier and produces a cleaner finished result.

Positioning the Rim Lock

With the door prepared, you're ready to position the rim lock. The body of the lock is normally installed centrally on the middle rail of the door, providing a balanced appearance and comfortable operating height.

Hold the lock in position and mark along its top edge with a pencil. This line will act as your reference throughout the installation.

Turn the rim lock over and measure two key dimensions: the distance from the narrow edge of the lock to the centre of the mortice opening, and the distance from the top of the lock to the centre of the same opening.

Transfer these measurements onto both sides of the door. This will accurately locate the hole for the threaded mortice bar that connects the two door knobs.

Drill a 12 mm hole through the marked position to allow the mortice bar to pass through the door.

Next, drill pilot holes for the rim lock fixings using a drill bit slightly smaller than the supplied screws. This gives the screws plenty of timber to grip while reducing the risk of splitting the wood.

At this stage, it's worth temporarily securing the lock using a standard Pozi-drive screw rather than the decorative screws supplied with the lock. As the lock will be removed again before painting, this helps keep the original screws in good condition for the final installation.

The next component to fit is the striker plate. Align it with the lock body before carefully marking around the three edges that sit against the architrave.

Using a straight edge and a sharp Stanley knife, score along these pencil lines before beginning to chisel. This creates a crisp edge and greatly reduces the chance of the timber splintering.

Carefully remove the waste material with a sharp chisel. Some people find it easier to use the chisel upside down for greater control while paring away small amounts of timber.

Once the recess has been cut, drill the pilot holes and temporarily secure the striker plate using the same sacrificial screws.

With both the rim lock and striker plate correctly positioned, you're ready to move on to fitting the door knobs.

Choosing the Correct Kind of Door Knob

With the rim lock and striker plate installed, it's time to choose the correct door knobs. When fitting a rim lock, your choice of knob affects both the appearance of the door and the way the lock operates.

One of the first things to check is that the rose plates are removable rather than fixed. The side of the door carrying the rim lock does not require a rose plate, while the opposite side does. A removable rose allows the knob set to be fitted correctly.

You'll also need a door knob set that uses a threaded square mortice bar. This connects the two knobs through the door and the rim lock, creating a secure fixing. The knobs are then locked in position using small grub screws.

If you're unsure what to look for, we've put together a collection of door knobs specifically designed for rim locks. These sets include the correct fittings and make choosing compatible hardware much easier.

You can also browse our full range of interior door knobs to find a style that complements your property.

Fitting the Door Knob to the Rim Lock

Once you've chosen the correct door knob set, you're ready to install it. Although this stage may seem complicated, it's straightforward when broken down into a few simple steps.

Begin by measuring the combined thickness of the door and the rim lock. This determines the required length of the threaded mortice bar that connects the two knobs.

Adjust the mortice bar to the correct length before fixing one door knob permanently onto it. Pass the assembly through the rim lock and out through the opposite side of the door.

Slide the rose plate over the exposed mortice bar and carefully align it with the hole in the door. Once you're happy with its position, mark the fixing holes with a sharp pencil.

Remove the rose plate and drill two pilot holes, angling the drill slightly. This creates enough clearance for the screws once the door knob has been fitted.

You can now install the second door knob by winding it onto the threaded mortice bar until it just meets the recessed face of the rose plate.

Turn the knob back slightly until the grub screw faces directly downwards. This allows the grub screw to engage with the flat section of the mortice bar, securing the knob in the correct position.

Once both knobs have been tightened, test the lock several times to ensure the latch operates smoothly and the door opens and closes correctly.

Disassembly, Painting, and Reassembly

Before carrying out the final installation, it's worth removing the hardware one last time to paint the door. Although this adds an extra step, it produces a much cleaner finish around the lock and door knobs.

Carefully remove the rim lock and door knobs before applying your chosen primer and topcoat. Allow the paint to dry fully and harden before refitting any hardware.

When you're ready to reassemble everything, replace the temporary sacrificial screws with the matching screws supplied with the rim lock. This small step makes a noticeable difference to the finished appearance.

For the final installation, we recommend using a hand screwdriver rather than a power drill. A hand screwdriver provides greater control and reduces the risk of damaging the screw heads or marking the new finish.

Once everything has been tightened and checked, your new rim lock installation is complete. Take a few moments to test the lock and admire the finished result.

Related Rim Lock Blog Posts

If you'd like to learn more about rim locks and traditional door hardware, these guides may also be useful:

• What Is a Rim Lock?
• Do I Need a Rim Lock or Mortice Latch?
• Where to Fit a Rim Lock
• Are Rim Locks Secure?
• Are Rim Locks Reversible?

Frequently Asked Questions

What tools do I need to fit a rim lock?

You'll typically need a drill and suitable drill bits, wood chisels, screwdrivers, a pencil, tape measure, hammer and combination square.

Should the rim lock go on the inside or outside of the door?

Install the rim lock on the inside face of the door—the side the door opens towards—so the key operates it from the outside.

For a more detailed explanation, including diagrams and common exceptions, see our guide: Where to Fit a Rim Lock – Inside or Outside?.

Do rim locks work on every type of door?

Rim locks are suitable for most solid timber doors. Very thin or hollow-core doors may require reinforcement before installation.

Are rim locks handed? How do I choose left or right?

Yes. Traditional rim locks are handed.

If your hinges are on the left when viewing the side where the lock will be fitted, you'll need a left-handed rim lock. If the hinges are on the right, you'll need a right-handed version.

For a full explanation with illustrations, read our guide: Are Rim Locks Reversible?.

Can I install a reversible rim lock?

Yes. Some rim locks are reversible and can be configured for either handing. Always check the product specification before purchasing.

Does the strike plate need to be chiselled into the frame?

Yes. The strike plate should be recessed into the door frame so that it sits flush with the timber. This provides a neater appearance and allows the lock to operate correctly.

How do I maintain a rim lock?

Periodically tighten any loose screws, lightly lubricate the internal mechanism where required, and clean the external finish with a soft cloth suitable for the material.

Can a rim lock be fitted to an external door?

Yes, although we recommend using a suitable deadlock or deadbolt where additional security is required. A standard rim lock on its own may not provide the level of security expected for many external doors.

Handy External Links

Explore these additional resources to learn more about rim locks and their history.

• Rim Lock – Wikipedia
  Overview of rim lock history, design and development.
• Historic Rim Lock – Mount Vernon
  An eighteenth-century rim lock from George Washington's home.
• Old Town Home – Restoring a Rim Lock
  A detailed photographic guide to dismantling and restoring an antique rim lock.