BS3621 Locks Norfolk

BS3621 Locks Norfolk — Insurance-Grade Timber Door Deadlocks Fitted

If your home insurer asks for a “British Standard lock” or a “BS3621 mortice deadlock”, they’re talking about the same thing: a five-lever mortice deadlock that’s been independently tested to BS3621. Fit one to every final-exit timber door and you’re meeting the lock clause in nearly every household policy in the UK. We’re Alan and his brother — Norfolk locksmiths, family-run from Briston near Holt, DBS-checked, fully insured, and on call 24/7 right across the county for BS3621 lock supply and fitting.

When you’ll need a BS3621 lock

You’ll usually come across BS3621 in one of three situations:

  • Your insurer’s wording requires it. AXA, Aviva, Direct Line, LV, Admiral and most mainstream UK home insurers specify that final-exit timber doors must be fitted with “a five-lever mortice deadlock conforming to BS3621” — or wording very close to that.
  • You’ve had a claim refused or queried. Loss adjusters check locks. If the door that was forced wasn’t BS3621, you may find the claim disputed.
  • You’re moving into an older Norfolk property. Many of the cottages and period homes around Holt, Aylsham, Cromer and Sheringham still have three-lever locks or non-standard mortice gear from decades back. Those don’t meet modern insurance criteria.

Who this page is for

Homeowners and landlords in Norfolk with a timber front, back or side door who want to be certain the lock they’ve got — or the one we’ll fit — meets a recognisable British Standard. If you’re not sure what’s on your door, we can identify it on the callout and tell you whether it qualifies. No pressure, no upsell. If the lock you’ve already got is BS3621 and working properly, we’ll tell you that and move on.

What’s included when we fit a BS3621 lock

  • Inspection of the existing door, lock case and keep.
  • Supply of a genuine BS3621-marked five-lever mortice deadlock (we’ll talk through the brand options below).
  • Mortice prep — squaring out the existing pocket or cutting a fresh one if you’re moving from a different lock pattern.
  • Fitting the new lock case, faceplate and forend.
  • Aligning the strike plate and keep so the bolt throws cleanly without forcing.
  • Testing through a full key cycle — from outside, from inside, both ways, locked and unlocked.
  • Two or three keys cut to match (depending on the brand and what’s on the box).
  • Disposal of the old lock if you don’t want to keep it.
  • A receipt with the lock brand, model and “BS3621 compliant” written on it — useful if your insurer asks for evidence.

What BS3621 actually means

BS3621 is the British Standard for thief-resistant single-point locks, operated by a key from both sides. The current version is BS3621:2007+A2:2012, and the lock has to pass independent tests for resistance to picking, drilling, sawing and forcing. Look for the British Standard kitemark — the stylised heart-shape with “BS3621” stamped on the forend (the visible metal plate on the edge of the door).

A few things people often get wrong about BS3621:

  • Not every five-lever mortice deadlock is BS3621. Some are five-lever but haven’t gone through the test programme. The kitemark is the proof.
  • BS3621 is for the final-exit door — the one you lock when you leave the house. If you’ve got a back door that’s never used as the main exit, BS8621 (key from outside, thumbturn from inside) may be more appropriate for fire-escape reasons.
  • BS3621 is a timber-door standard. uPVC and composite doors meet insurance criteria differently, usually via a TS 007 3-star or SS 312 Diamond euro-profile cylinder paired with a kitemarked multipoint lock.

Brands we routinely fit

We’re not tied to one supplier. The right BS3621 lock for your door depends on the door thickness, the existing mortice pocket and what you want to spend. The brands we use most often in Norfolk:

Chubb 3G114E

The benchmark insurance-spec mortice deadlock. The 3G114E is what loss adjusters look for first. Hardened steel bolt, anti-pick detainers, drill-resistant plate. If your insurance is particular, this is the one we’ll usually recommend.

ERA Fortress

A solid mid-range BS3621 deadlock — five levers, hardened bolt, kitemarked. Easier on the wallet than the Chubb but still ticks every insurance box.

Yale PM550

Yale’s BS3621 five-lever mortice deadlock. Widely fitted across the UK, easy to source, and Yale’s after-sales support is good if you ever need spare keys cut down the line.

Union 2A51 / 2A52

Long-established locks you’ll often find on Norfolk’s older properties when replacing like-for-like. Union’s BS3621 range stays compatible with mortice pockets that are decades old.

Insurance considerations

Before you commit to a lock change, dig out your home insurance schedule and find the section headed “Security” or “Lock specification”. You’re looking for one of these phrases:

  • “five-lever mortice deadlock to British Standard 3621”
  • “BS3621-compliant deadlock on all final exit timber doors”
  • “a mortice deadlock with the British Standard kitemark”

If the wording’s tighter than that — say it specifies a particular brand or rating — let us know on the call and we’ll bring exactly what’s required. Photograph the new lock once it’s in. Keep the receipt and the lock’s packaging. If you ever have to claim, the loss adjuster will ask, and that paperwork makes life easier.

One more thing: insurance lock clauses often have a condition that “all locks must be operated when the property is unoccupied”. A BS3621 lock fitted but not actually deadlocked when you leave won’t save a claim. We mention this every callout — it’s the bit people forget.

Timing expectations

For a straightforward like-for-like BS3621 swap on a door that already has a five-lever mortice pocket, we’ll usually be in and out within the hour. If we’re cutting a fresh mortice into a door that’s only had a nightlatch, allow longer — sometimes two hours, depending on the door thickness and whether the door has to come off its hinges.

Drive times to your door depend on where you are in Norfolk. We’re based at Briston, between Holt and Reepham, so Holt, Aylsham, Cromer, Sheringham and Fakenham are typically within 25 minutes during the day. Norwich is usually 35-45 minutes. King’s Lynn, Wymondham and Great Yarmouth are typically 50-60 minutes. Diss and the far south of the county can be over an hour. We cover all of it — we just won’t promise a 30-minute arrival to somewhere we can’t reasonably get to in 30 minutes.

ID we’ll show on arrival

Photo ID, DBS certificate available on request, business card with our landline and mobile, and the van’s signwritten. If you ever have any doubt about a tradesperson at your door — us or anyone else — ask through a chained door first and call to verify. We’d far rather you took two minutes to check than open up unsure.

Common mistakes we see

  • Buying the lock first, then ringing a locksmith. Half the time the lock people buy off the shelf is the wrong case size for their door, or it’s a five-lever lock without the BS3621 mark. Ask us first.
  • Assuming a kitemark stamp on the key means BS3621. The kitemark you want is on the forend of the lock — the metal strip on the edge of the door — not on the key bow.
  • Fitting BS3621 to a fire-escape door. If the door is a designated escape route (especially in flats and HMOs), BS8621 with a thumbturn inside is what you want — not a key-both-sides BS3621.
  • Leaving the original keep in place. An insurance-grade deadbolt going into a tired softwood frame is only as strong as the keep it’s throwing into. We replace the strike plate and screw into solid timber wherever possible.

FAQs

Does my insurer really check the lock standard?

Loss adjusters do, after a forced-entry claim. Day to day, no one’s checking — but the wording in the policy stands. If a claim comes up and the lock didn’t meet the policy spec, the insurer has grounds to argue.

How do I know if my existing lock is BS3621?

Open the door, look at the metal strip on the edge of the door where the bolt comes out (the forend). A BS3621 lock will have the British Standard kitemark stamped there, along with “BS3621”. If it just says “5 lever” or has a brand name with no kitemark, it’s not BS3621-rated.

Can I fit a BS3621 lock myself?

Legally, yes. Practically, a mortice deadlock fitted slightly off-square will bind, fail to throw cleanly, and the bolt won’t engage the keep properly — which defeats the security. If you’re confident with chisels and templates, go ahead. If not, the saving rarely justifies the headache.

What if my door is too thin for a BS3621 mortice case?

Some older Norfolk doors — particularly internal-stock doors used as external doors — are too thin to take a 76mm case. You can sometimes fit a 64mm case instead, and there are BS3621-rated 64mm options. We’ll measure on arrival and tell you what’ll fit.

Is BS3621 the same as TS 007?

No. BS3621 is the standard for timber-door mortice deadlocks. TS 007 is the standard for euro-profile cylinders, used on uPVC and composite doors. Different door types, different standards, both insurance-recognised.

Do I need BS3621 on the back door too?

Most policies require it on all final-exit timber doors. If the back door is genuinely never used as an exit and is bolted top and bottom, check the exact policy wording — sometimes a sash lock with a BS3621 deadbolt section is acceptable, but it varies.

Will fitting a BS3621 lock reduce my insurance premium?

Sometimes a little, sometimes not — it depends on the insurer. The bigger effect is that fitting one keeps the policy valid in the event of a claim. That’s the real saving.

Do you supply the lock or do I?

Either. If you’ve already bought one, we’ll fit what you’ve got (subject to checking it’s actually BS3621 and the right case size). If you haven’t, we’ll bring options to your door.

Can you fit BS3621 to a Victorian door without ruining it?

Almost always, yes. Old Norfolk doors are generally robust enough to take a fresh mortice. We work neatly, the new lock sits flush, and from the outside the door looks the same. Where the door is genuinely fragile or of conservation interest, we’ll discuss options before cutting anything.

Related services

Areas we cover for BS3621 lock fitting

Holt, Aylsham, Cromer, Sheringham, Fakenham, Wells-next-the-Sea, North Walsham, Hoveton, Wroxham, Mundesley, Stalham, Norwich, King’s Lynn, Wymondham, Great Yarmouth, Diss, Loddon — and every village and hamlet in between. If you’re in Norfolk, we’ll come.

24/7 emergency locksmith — covering Norfolk
Call 07846 643176