BS3621 · explained · Manchester
The five words that decide whether you get paid.
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- Check yours in 10 seconds
- Fitted £85-140
- Survey £45-75
- We'll say if you're fine
Somewhere in your home insurance is a sentence about locks. Most people never read it. It is usually the only clause in the whole document that can turn a paid claim into a declined one, and checking whether you comply takes about ten seconds.
What BS3621 is
BS3621 is a British Standard for thief-resistant locks. A lock carrying it has been tested against drilling, picking, and being forced, and it must be key operated from both sides, so nobody can leave through it without a key. That last part is the bit that matters to insurers: a burglar cannot walk out of your front door carrying your television.
In practice, on a wooden door, BS3621 usually means a 5-lever mortice deadlock. Not every 5-lever lock is BS3621, which is where a lot of confusion starts.
Check yours right now
Open the door and look at the metal faceplate on the door edge, where the bolt comes out.
- Kitemark (a heart-shaped symbol) stamped on it
- The words BS3621 next to it
- A year, like BS3621:2007
If it is not stamped there, it is not BS3621. There is no hidden marking and no benefit of the doubt. "It's a good lock" and "it's 5-lever" are not the standard.
The three numbers, and which one you need
| Standard | Getting out | Where |
|---|---|---|
| BS3621 | Key needed both sides | Houses. What most policies ask for. |
| BS8621 | Thumbturn inside, no key | Flats and HMOs where fire escape rules apply |
| BS10621 | Thumbturn, unless locked from outside | Holiday lets, second homes |
If you live in a flat, your fire risk assessment may forbid the very lock your insurer asks for. That is a real conflict, not a technicality, and BS8621 usually resolves it. Ask us rather than guessing.
Where Manchester homes fail
Three patterns, over and over:
Front done, back ignored
Wording says all external doors. Back door still has a 2-lever from 1974, facing a garden nobody overlooks.
uPVC confusion
uPVC doors do not have mortice locks. Your policy's BS3621 clause may apply differently or not at all. Read it, don't assume.
Nightlatch mistaken for it
A Yale on the front is not a deadlock. BS3621 nightlatches exist, but the common ones are not.
Windows forgotten
Most policies also want key-operated locks on accessible windows. See window locks.
What it costs
| Job | Price |
|---|---|
| BS3621 5-lever mortice, supplied and fitted | £85-140 |
| BS8621 for a flat (thumbturn, escape) | £95-150 |
| BS3621 nightlatch | £75-130 |
| Whole property survey + written report | £45-75 |
If you already comply, we will tell you and charge you for the survey rather than inventing an upgrade. That happens more than you would think, especially on newer builds.
Insurance work · Mortice locks · Security upgrade
Questions people actually ask
How do I know if my lock is BS3621?
Open the door and look at the metal faceplate on the edge of the door, where the bolt comes out. A BS3621 lock has the Kitemark, a heart-shaped symbol, stamped into that plate, usually with the words BS3621 and a year next to it. If it is not stamped there, it is not BS3621. There is no hidden marking and no benefit of the doubt. A lock being solid, expensive, or 5-lever does not make it BS3621, because not every 5-lever mortice lock is tested to the standard.
Will my insurer really refuse to pay if my locks aren't BS3621?
They can, and it is one of the few clauses that lets them decline a claim outright rather than reduce it. If your policy states BS3621 on final exit doors and you did not have it, the insurer's position is that you did not meet a condition of cover. Whether they enforce it varies, but you do not want to find out. The clause is usually in the general conditions or the theft section, and it takes two minutes to find. If you disagree with a decision, the Financial Ombudsman Service is free once you have a final response letter.
My back door isn't BS3621 but my front door is. Is that a problem?
Very likely, and it is the single most common gap we find in Manchester homes. A lot of policies say all external doors, not final exit door, and people upgrade the front because that is the one they think about. The back door then still has a 2-lever lock from the seventies, facing a garden nobody can see into, which is exactly where anybody sensible would try. Read the wording. If it says all external doors, the back needs doing too, at £85 to £140 fitted.
I live in a flat. My insurer wants BS3621 but the fire rules say otherwise. What now?
This is a genuine conflict and you are not misreading it. BS3621 needs a key to get out, which a fire risk assessment for a flat will usually forbid, because in a fire you should not be hunting for a key. The answer is normally BS8621: same thief resistance, tested to the same attacks, but with a thumbturn inside so you can always leave. Most insurers accept BS8621 for flats specifically for this reason. Tell your insurer it is a flat with escape requirements and ask them to confirm BS8621 in writing.
Does BS3621 apply to my uPVC door?
Not in the same way, and this trips people up constantly. BS3621 is a mortice lock standard, and uPVC doors do not have mortice locks, they have multipoint mechanisms driven by a euro cylinder. Some policies word the clause so it only bites on wooden doors; others ask for a cylinder standard like TS007 3-star instead. Read yours rather than assuming either way. If your uPVC door is the final exit and the wording asks for BS3621, ring your insurer, because the clause may not be applicable and they should tell you what they actually want.