Whether you’ve just moved to a new home or are looking to beef up the security of your current house, changing your front door lock is often the first port of call. However, as anyone who’s had to do this type of work in the past will tell you, it can cost upwards of £100, depending on the type of lock you have. This has led many DIY-savvy homeowners to attempt the job themselves.  

Fortunately, the act of replacing the lock itself is not a particularly difficult one, however, there are some things may need to know before your start. Below we’ll go through how to replace the three most common types of front door locks (Euro Profile, Mortice Deadlock and Cylinder Rim) as well as how to install security bolts on wooden doors for added peace of mind and, potentially, even a better deal on your home insurance. 

• How to Replace a Euro Profile Cylinder Lock 
• How to Replace a Mortice Deadlock 
• How to Replace a Yale Lock (Rim Cylinder) 
• Installing Security Bolts 
• Keeping Your Locks Clean 

Unlike some other locks, Euro Profile Cylinders all have the same design and shape, this makes finding a replacement yourself much easier than it might otherwise be. However, you should still take the time to make sure that the new lock is the same size as the old one.  

To get an idea of the size of your current lock you should measure from the centre of the fixing screw to the outside of the lock on either side of the door. If the length on either side is 40mm, you be looking for a 35:10:35 product, that’s 5mm taken from either side and added to the middle. So, for a lock with measurements of 45mm and 40mm, it would be 40:10:35.  
You should also make sure that the lock does not stick out more than 5mm from the door handle faceplate as this will make it vulnerable to lock snapping. A common method used by burglars across the UK. 

Step-by-Step 

Step 1: Remove the Central lock Fixing Screw 

Open your door and carefully remove the fixing screw. It is worth checking the screw’s condition here as you may want to replace this as well. 

Step 2: Loosen the Door Handles 

Loosen the door handles, but do not remove them. This will just make the cylinder easier to remove. 

Step 3: Remove the Current Lock 

Place your key in the lock and slowly pull it towards you whilst tuning it to the 10 or 2 positions so as to align the cam tongue to the lock’s main body. When this is aligned the lock should slide out. 

Step 4: Fit the New Lock 

Gently slide the new lock into position and replace the fixing screw. Finally, tighten up the door handles and your new lock will be fully installed. 

Step 5: Use the Key to Test 

Double check the lock is working before closing the door. Make sure to do this on both sides. 

Mortice locks typically come in two different styles, a Sashlock which is commonly used on side entrances and backdoors, and a deadlock, the type we’ll be going through below as well as what is most common on front doors. They have been produced in such a way as to be rebated into the door, providing a cleaner and neater look. 

The important thing to remember when replacing a Mortice lock is to look for one similar to your current lock. It should have the same distance between the centre of the keyhole and the centre of the spindle that connects the handles. If you can find one with a similar size of faceplate and strike plate, that would be even better. 

You should also measure your current lock to get an idea of the size that will be needed. Start at the back set and measure to the front edge of the door, to the centre of the keyhole. If the distance is 45mm you will need a 65mm lock. If the distance is 57mm you will need a 75mm lock. 

Rim Cylinder locks are most commonly seen in use on wooden front doors and are sometimes known as Yale locks. They have the benefit of providing simple security, whilst still being relatively cheap to replace, with some costing as low as £10. 

Step-by-Step 

Step 1: Unscrew Lock Body 

Open your door and unscrew the body of your current lock. Make sure to keep this safe to one side for now as it will be reinstalled with the new lock. 

Step 2: Remove the Existing Cylinder Rim 

Unscrew the cylinder rim (screws will be located behind the lock body on the back of the door) and carefully remove it whilst keeping the mounting plate attached to the door. 

Step 3: Shorten New Tail Bar (if needed) 

Check the length of your new lock. If it is longer than the old one, cut it down with a hacksaw until they are the same length. 

Step 4: Fit New Cylinder 

Push the new cylinder in place and fix it into the mounting plate with the screws which should have been included. 

Step 5: Re-affix Lock Body 

Finally, screw the lock body back into position and test the lock to make sure it is functional. 

As an added bit of security besides the doors main lock, you can also install some Security Bolts. These provide a secondary layer of protection if, worst case, the lock is broken or picked. 

Step-by-Step 

Step 1: Pick out the Appropriate Wood Drill Bit 

Before starting any work make sure that you are using a wood drill bit and that it is the same size as what will have been recommended in the bolt manufacturer’s instructions. You can mark the length of the bolt on the bit with some masking tape to make sure you don’t drill too deep into the door. 

Step 2: Drill Holes in Your Door 

These holes should be drilled to the marked depth in the centre of the edge of the door, ideally near the top and bottom. 

Step 3: Check Your Bolt Fits 

Place your bolt into the drilled holes to make sure it fits flush against the edge of the door. You should then mark an outline of the end plate on the edge of the door. 

Step 4: Create Area for End Plate to be Installed 

Remove the bolt and end plate and, using a hammer and chisel, carefully chip away at the marked area so that the end plate can sit level with the edge of the door. 

Step 5: Mark the Positions of the Key Holes 

Hold the bolt against the inside of the door and mark the position of the keyhole using a carpenter’s awl. 

Step 6: Drill Key Holes 

Again, pick out a drill bit of the recommended size and then drill the keyholes in the marked positions. Make sure that these do not go right through the door. 

Step 7: Check the Bolt and Key Line Up 

Put the bolt back into the door and check that it lines up with the key and can be turned smoothly. 

Step 8: Mark End Plate & Key Plate Screw Holes 

Mark the position of the endplate screws on the edge of the door using a pencil. 

Step 9: Drill End Plate & Key Plate Screw Holes 

Drill pilot holes using a small wood drill bit before screwing the end plate and key plate into the door. Again, double-check that the key plate lines up and that the bolt turns smoothly. 

Step 10: Install Strike Plates 

Following a similar process to the above, create the area and screw the strike plates into position. The majority of security bolts have a small bump on the end, meaning they can be used to make a small mark against the door frame for added accuracy when installing. 

With your new lock in place your home should be that much more secure, but if you want it to stay that way it is important that you keep your locks in good nick. They should be kept lubricated to ensure they don’t get stiff and stay in good working condition. Be sure to only use products that are suitable for use with your specific lock’s material and finish.