Quick answer
BS3621 is the British Standard for thief-resistant locks that need a key to open from both sides. It's the standard many UK insurers name for final exit doors.
What the standard covers
BS3621 locks are tested for resistance to drilling, picking, sawing and forcing, and must have a minimum number of key differs.
How to spot one
The faceplate on the edge of the door is stamped 'BS3621' with a kitemark. Common types are 5-lever mortice deadlocks and British Standard nightlatches.
Related standards
BS8621 locks can be opened from inside without a key, for easier escape. BS10621 is for multi-occupancy buildings.
Related services
- British Standard Locks — BS3621 and kitemarked locks that meet insurance requirements.
- Mortice Locks — BS3621 mortice deadlocks and sashlocks fitted, repaired and replaced.
- Yale & Nightlatch Locks — Rim nightlatches repaired, replaced and upgraded to British Standard.