Quick answer: BS3621 is a British Standard that certifies a lock has passed independent testing for resistance to drilling, picking, forcing and snapping. Insurers often require it because it proves your lock meets a trusted level of security. You can spot the mark stamped on the lock body itself, usually the kitemark symbol alongside the number.
If you have ever read through your home insurance paperwork, you may have spotted a mention of BS3621. It usually turns up in the small print about locks, and for most people it means very little at first glance. I get asked about it all the time out on jobs across Southampton and the Waterside, so I thought I would sit down and explain what it actually means in plain English.
I fit and repair locks every week, and BS3621 is one of those things that sounds far more complicated than it really is. Once you understand what it is and why it matters, you can check your own doors in a couple of minutes. Let me walk you through it.
So what exactly is BS3621?
BS3621 is a British Standard for locks. The BS bit simply stands for British Standard, and the number is just the reference for this particular one. It sets out a list of requirements that a lock has to meet to be considered secure enough for insurance purposes. That covers things like how long the bolt is, how resistant the lock is to being drilled, picked or forced, and how well it holds up to someone trying to snap or manipulate it.
The important thing to understand is that BS3621 is a tested and approved standard. A lock cannot just claim to be secure. To carry the BS3621 mark it has to be sent off, tested to destruction in a lab, and pass. That is why insurers trust it. It takes the guesswork out of whether a lock is any good.
You will usually find it on mortice deadlocks for wooden doors and on rim automatic deadlocks, which are the kind of lock that latches shut behind you and can be deadlocked with the key. For UPVC and composite doors the picture is a little different, and those tend to use a different standard, but the principle is the same. The lock has been independently tested and proven.
Why do insurers care so much about it?
Insurers care because they want to know your home is secured to a decent level before they agree to cover it. From their point of view, a house with proper tested locks is far less likely to be broken into, and if it is broken into, there is proof that you did your bit to keep it secure.
Here is where a lot of people come unstuck. Many home insurance policies say, in that small print, that your final exit door and other accessible doors must be fitted with a lock that meets BS3621. If you have not got it and you make a claim after a break in, the insurer can turn round and reduce your payout or even refuse it altogether. That is a horrible position to be in, and it is completely avoidable.
I have seen it happen to good people who had no idea their locks fell short. They assumed that because their door locked, they were fine. Sadly, that is not how insurers see it. If you want to understand more about how this ties into your cover, I have written a fuller piece on BS 3621 lock changes in Southampton that goes into the detail.
How can I tell if my locks meet BS3621?
The good news is that it is usually easy to check yourself. A genuine BS3621 lock will be stamped with a kitemark. That is a little heart shaped symbol, and next to it you should see the number BS3621 along with a year, such as 2007. On a mortice deadlock you will often find this stamped on the faceplate, which is the metal strip on the edge of the door that the bolt comes out of. You might need to open the door and look closely, and a wipe with a cloth can help if it is a bit grubby.
On a rim lock, the kitemark is often found on the lock body itself or on the faceplate. If you cannot see any kitemark or BS3621 marking at all, then in all likelihood your lock does not meet the standard. Age is a good clue too. If your locks are decades old, they were probably fitted long before this became a common insurance requirement.
If you are not sure, do not worry about it. This is exactly the sort of thing I am happy to check when I am passing. I can look over your doors, tell you honestly what you have got and what you need, and if a lock does need swapping I will fit one that meets the standard properly.
What should I do next?
My advice is simple. Dig out your insurance policy and look for any mention of BS3621 or approved locks. Then go and check your doors for that kitemark. If everything matches up, brilliant, you can relax. If it does not, it is worth sorting sooner rather than later, before you ever need to make a claim.
I cover Southampton and the whole SO45 Waterside area, I am available 24 hours, and I never charge a call-out fee. If you want a straight answer about your locks with no pressure and no fuss, give me a ring and I will come and take a look.
What if your door is the only way out, like in a flat?
Here is something worth knowing before you rush out and fit a BS3621 lock. A standard BS3621 mortice deadlock needs a key to open it from the inside as well as the outside. On most homes that is fine, but if your door is the only way out, say in a flat or a bedsit, that can be a real safety problem in a fire. You do not want to be hunting for a key in the dark with smoke about. For those situations there are related standards, BS8621 and BS10621, that let you get out without a key while still keeping the security on the outside. If you are not sure which one suits your door, give me a shout and I will take a look.
According to what I have seen on jobs across Southampton and the Waterside over the years, folk in flats often fit the wrong type of lock without realising it could trap them in a fire.
Does the year on your BS3621 lock actually matter?
Here is something folk often miss. BS3621 has been through a few different versions over the years, and you will sometimes see a date stamped next to the number, like 1998, 2007 or 2017. The later the version, the tougher the testing the lock had to pass. So if your lock was fitted a long while back it might still carry the kitemark, but it could be an older version than your insurer now expects. Over the years working across Southampton and the Waterside I have seen plenty of old locks that were fine in their day but no longer tick the box. If you are unsure, have a proper look at the faceplate, and if in doubt give me a shout. No call-out fee, 24 hours.
How can you tell a real BS3621 lock from an ordinary five-lever one?
This is where folks trip up. Not every five-lever mortice lock is British Standard, and I see the mix-up on jobs all over Southampton and the Waterside. For a mortice deadlock to meet BS3621 it has to have at least five levers AND a bolt that throws at least 20mm into the frame when locked. Plenty of older or cheaper locks have five levers but fall short on the bolt or the internal build, so they never earned the kitemark. That is why the stamped mark matters more than the lever count. If your lock has five levers but no kitemark on the faceplate, it likely will not satisfy your insurer. Not sure? I will check it for you. No call-out fee, 24 hours.
Frequently asked questions
What exactly is BS3621?
BS3621 is a British Standard for locks. It sets out requirements a lock must meet to be secure, covering bolt length and resistance to drilling, picking and forcing. To carry the mark, a lock is tested to destruction in a lab and must pass, which is why insurers trust it.
Why do insurers care about BS3621?
Insurers want proof your home is secured to a decent level before covering it. Many policies state in the small print that your final exit door and accessible doors must have BS3621 locks. If yours fall short and you claim after a break in, they can reduce or even refuse your payout.
How can I tell if my locks meet the standard?
Look for a kitemark, a little heart shaped symbol, stamped on the lock. Next to it you should see BS3621 and a year, such as 2007. On mortice deadlocks check the faceplate on the door edge. If there is no marking at all, your lock likely does not meet the standard.
Can Bugsy check my locks for me?
Absolutely. Fitting locks across Southampton and the Waterside, I am happy to look over your doors, tell you honestly what you have got and fit a proper BS3621 lock if needed. I am available 24 hours and never charge a call-out fee, so just give me a ring.
