Everything You Need to Know About Door Lock Replacement

Why Door Lock Replacement Matters

Replacing a worn, outdated, or compromised door lock is one of the most straightforward ways to improve the security of a property. It is also one of the most frequently overlooked. Many homeowners live with locks that are years past their useful life, not realising how much that reduces their security.

This guide covers everything you need to know to make the right decision about door lock replacement.

Types of Door Locks

Deadbolts

The most common lock type for external doors in UK homes and businesses. Deadbolts extend a solid metal bolt into the door frame when locked, offering excellent resistance to forced entry. They come in two configurations:

Single cylinder: key outside, thumb turn inside - the standard choice for most residential doors
Double cylinder: key required on both sides - useful where there is glass near the lock, but requires careful consideration in case of fire

Mortice Locks

Mortice locks are fitted inside the door body rather than on its surface, making them inherently stronger and more tamper-resistant. They typically combine a latch and a deadbolt in a single unit. Common in older UK properties and many commercial buildings, mortice locks are considered more secure than standard deadbolts when correctly installed.

Knob Locks

Knob locks enclose the locking mechanism within the door knob itself. They are suitable only for interior doors - they can be forced open with basic tools and should never be used as the sole lock on any external door.

Euro Cylinder Locks

The standard lock type for uPVC and many composite doors. The cylinder is the replaceable core of the locking mechanism, making it easy to upgrade security without replacing the entire lock body. When fitted to an external door, always choose a cylinder with anti-snap, anti-pick, and anti-drill protection.

Smart Locks

Smart locks allow access via smartphone, keypad, or biometric reader. They can be integrated with home automation systems and provide features such as remote locking, access logs, and temporary credentials for guests. Smart locks are an increasingly popular upgrade, though they work best alongside - rather than instead of - a quality mechanical lock.

When Should You Replace a Door Lock?

Signs of Wear and Tear

The key feels stiff or requires effort to turn
The lock or handle feels loose or wobbly
The bolt does not extend or retract smoothly
You can see visible wear or damage on the cylinder face

Lost or Stolen Keys

If your keys have been lost or could have been copied, replace the lock. Even if the keys are later found, you cannot be certain they were not duplicated while out of your possession.

Moving Into a New Property

Always replace the locks when you move into a new home or business premises. Previous occupants, tradespeople, or their contacts may have copies of the existing keys.

After a Security Incident

If your property has been broken into, or if there are signs of tampering on the lock, replace it immediately. A lock that has been attacked may appear to function normally while being structurally compromised.

Security Upgrade

If your current lock does not carry a recognised security certification, upgrading to a BS 3621-rated or Sold Secure Gold product offers a meaningful improvement in protection.

The Door Lock Replacement Process

Step 1: Assess Your Current Lock

Before purchasing a replacement, understand what you have. Note the lock type, brand, and model number if visible. For euro cylinders, measure the existing cylinder carefully - note the overall length and the distance from the centre of the fixing screw to each end (e.g. 35/45mm). Getting this wrong means the replacement cylinder may not fit.

Step 2: Choose the Right Replacement

With the measurements and lock type confirmed, select a replacement that:

Fits your door correctly
Carries an appropriate security certification for the door’s purpose
Suits any specific requirements (anti-snap for uPVC, weather resistance for exposed locations)

Step 3: DIY or Professional Installation?

Replacing a euro cylinder in a uPVC door is a straightforward task that many homeowners can manage with basic tools and careful attention to sizing. Replacing a mortice lock or fitting a new deadbolt requires more skill and the right tools, and incorrect installation can leave the lock functioning poorly or creating a security gap.

For anything beyond a simple cylinder swap, professional installation is recommended. See our lock change service for transparent pricing and same-day availability.

Practical Tips for Choosing the Right Lock

Match the security level to the door’s purpose - external doors need certified locks; interior doors need convenience
Check your insurance policy - some insurers require specific lock standards; failing to comply may affect your cover
Consider key control - patented key systems prevent unauthorised copying
Do not prioritise aesthetics over function - a beautiful lock that fails is no lock at all

Get a Professional Lock Change Today

For expert advice on which lock is right for your door and professional installation you can rely on, visit our lock change service page or get in touch.

For transparent pricing, see our locksmith price list.