The Worst and Best Types of Locks for Your Home
Choosing the Wrong Lock Is a Costly Mistake
Homeowners often underestimate how much variation there is in the security offered by different lock types. Some locks that look entirely normal on a front door can be defeated in seconds by anyone with basic skills and common tools. Others require sustained, specialist effort - and announce the attempt loudly enough to drive any would-be intruder away.
This guide is direct about which locks belong on your exterior doors and which do not.
Locks That Offer Poor Security
Spring Latch Locks
Spring latches are the self-latching mechanisms often found on internal corridor doors, UPVC doors as a supplementary latch, or - unfortunately - on some residential front doors. They engage automatically when the door closes, which is convenient, but they can be opened with a flexible card slid between the door and frame in seconds. There is no deadbolting action. They should never be the primary security device on any exterior door.
Warded Locks
One of the oldest lock designs still in production, warded locks use a series of internal obstructions (wards) that prevent the wrong key from turning. However, a basic skeleton key that clears all the wards can open virtually any warded lock regardless of the specific key pattern. These are entirely unsuitable for securing valuable spaces.
Knob Locks on Exterior Doors
The classic round door knob containing an integrated cylinder lock is designed for interior privacy, not exterior security. The lock mechanism is built into the knob body itself, which can be sheared off or leveraged with a wrench or similar tool, exposing the simple mechanism behind it. If you have a knob lock on an external door, it should be accompanied by a deadbolt - ideally replaced entirely.
Locks That Offer Good Security
Deadbolts
A properly installed deadbolt is the foundation of residential door security. When locked, the solid steel bolt extends into the door frame (and ideally into the structural timber behind it), meaning the door cannot be forced inward without destroying the frame itself. Deadbolts resist the “credit card” and shimming attacks that defeat spring latches.
Single cylinder deadbolts use a key outside and a thumb-turn inside. They are the standard residential choice and are suitable for most exterior doors. The one vulnerability is a glass panel within arm’s reach of the thumb-turn.
Double cylinder deadbolts require a key on both sides, eliminating the glass panel vulnerability. However, they must be used with extreme care - in a fire or emergency, occupants must have the key readily accessible to exit. Never use a double cylinder deadbolt without a plan for emergency egress.
For best results, choose a deadbolt rated to British Standard BS 3621 and install the strike plate with 75mm screws into the structural frame.
Mortice Locks
Mortice locks are set into a pocket (mortice) cut into the door itself, making them far more resistant to forced entry than surface-mounted locks. The lock body is entirely enclosed within the door, and a quality mortice deadlock offers exceptional resistance to pulling, prying, and drilling attacks.
British Standard five-lever mortice deadlocks are the gold standard for wooden external doors and are required by most home insurers for a successful burglary claim.
Anti-Snap Euro Cylinders
Most uPVC and composite doors use a Euro cylinder format. Standard cylinders are vulnerable to a “snap attack” - where the external part of the cylinder is snapped off with a screwdriver and hammer, exposing the mechanism and allowing the door to be opened in under a minute. Anti-snap cylinders (rated TS007 3-star or higher) are designed to sacrifice the external portion cleanly while leaving the internal mechanism intact. They are an essential upgrade for any uPVC or composite door.
Smart Locks
Modern smart locks - particularly those with keypad, fingerprint, or app-based access - can offer excellent security combined with significant convenience. The best models use advanced encryption and resist physical manipulation as well as any high-security mechanical lock. Key advantages include no physical key to lose or copy, and the ability to revoke access instantly if a code is compromised.
Choose smart locks from reputable brands with regular firmware updates and strong security certifications. Avoid cheap, unbranded options where the software security is unknown.
Additional Security Measures That Complement Good Locks
The lock is only part of the security picture:
- Reinforced door frames - even the best lock is defeated if the frame splits on the first kick
- Hinge bolts - prevent hinges from being attacked on inward-opening doors
- Door viewers (spy holes) - allow you to identify callers without opening the door
- Security cameras and alarms - deter and document
Get the Right Lock for Your Door
If you are unsure whether your current locks meet modern security standards, City Locksmith London can carry out a security assessment and recommend the most appropriate upgrade for your door type and budget.
We supply and install high-security locks including BS 3621 mortice deadlocks, TS007-rated anti-snap cylinders, and smart lock systems. View our lock change services or see our locksmith price list.