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UPVC door extra lock beside the main cylinder

Updated: October 2026

The back door is uPVC, the handle lifts, and a second mortice is not an option because the lock is already a multipoint. A UPVC door extra lock, on this shelf, is a sash jammer or a handle clamp on top of that lock. It is not a second cylinder, and it is not a portable brace unless the threshold has a gap, which most do not. Match a hinged door, French doors or a slider, and keep the anti-snap cylinder. Prices are on the [additional door lock comparison](/hub/door-and-window-security/additional-door-lock). Peter F. used amazon.co.uk listings and UK lock guidance in October 2026. A qualifying purchase can earn a commission at no extra cost to you.

The back door is uPVC, the handle lifts, and a second mortice is not an option because the lock is already a multipoint. A UPVC door extra lock, on this shelf, is a sash jammer or a handle clamp on top of that lock.

Our top picks

hzuisst hzuisst French door handle lock

Best overall

hzuisst hzuisst French door handle lock
9.0/10about £19.99
View offer
Sandiyago Sandiyago sash jammer, 4 pack

Best value

Sandiyago Sandiyago sash jammer, 4 pack
8.6/10about £8.99
View offer
Door-Jammer DoorJammer DJ3 portable door lock

Rank 3

Door-Jammer DoorJammer DJ3 portable door lock
8.4/10about £22.72
View offer
On this page
  1. 1.The lock that actually matters
  2. 2.Jammer or handle clamp
  3. 3.What will not fit a uPVC door
  4. 4.What this shelf cannot do

The lock that actually matters

On a uPVC door the lock that stops a snap is the euro cylinder, not the white arm. Everest describes lock snapping as an attack on the cylinder, and treats a sash jammer as another layer if the lock is forced. You usually cannot add a second cylinder beside the first. Master Locksmiths Association advice puts the first upgrade at a TS 007 3-star cylinder or a Sold Secure SS312 Diamond, the same preference as the West Yorkshire Police note. Their jammer hardware starts around £12, and a fitted cylinder around £130. Those are their figures, not prices from this aisle. ProtectUK's order is to lift the handle and then lock it. A handle left down only latches the door. If the cylinder is unmarked, that is the locksmith visit.

Jammer or handle clamp

For a hinged uPVC or composite door, the matching extras are the non-locking packs: Sandiyago's four-pack at about £8.99, 4.5 from 1,338 reviews, and zgpzlhd's six-pack at about £7.99, 4.4 from 41. Reviewers used the four-pack as a temporary hold when a back-door lock had failed. A failed multipoint is not repaired by an arm. You twist it while you are home and clear it before you leave. The body goes on the frame when the door opens in, and on the moving sash when it opens out. Sandiyago reviews cite screws around 30 mm and spacers that sheared. If the pilot finds no steel, stop. Drill sizes are on the how to fit a sash jammer page. Two horizontal levers are the hzuisst clamp, about £19.99, 4.7 from 444 reviews, on or off in about a minute. It only works while it sits on the handles. Vertical and curved handles are out.
hzuisst hzuisst French door handle lock

Testsieger

hzuisst hzuisst French door handle lock
9.0/10about £19.99
View offer

What will not fit a uPVC door

A DoorJammer is usually the wrong uPVC buy. The maker says most uPVC doors have no under-door gap, and the brace needs an inward door with at least 3 mm on a flat floor. A weather bar ends it. Outward-opening uPVC is the wrong shape twice. The brace against a screw-on arm is on the portable or fixed page. Sliding doors are a different problem. Anobeyi and MeBantoo, both about £6.99, are drop bars. Anobeyi reviews include a patio frame too narrow to sit flush, and one UK header. MeBantoo's title says stainless steel and the material field says aluminium. A child who can reach the bar can lift it. The Annakideya bolt assumes an edge thick enough to screw, which a hollow profile often is not. One review says the frame plate bent in a burglary.

What this shelf cannot do

This shelf cannot give you a keyed jammer from the garden, a second cylinder, or a PAS 24 door. If the multipoint has failed on the only exit, the clamp or the jammer is the night you are in, and the locksmith is the repair. On a fire door, do not add a fastening you cannot clear without hunting for a key. The type choice, before the frame detail, is on the buying guide.

Common questions

Can I put an extra lock on a uPVC door?
Yes, as a second layer, if the shape matches. A non-locking sash jammer suits a hinged uPVC door while you are in. A handle clamp suits two horizontal levers and needs no drill. You cannot add a second mortice. The cylinder and the multipoint remain the lock. If the frame is hollow and the pilot finds no steel, stop and use jack nuts or a locksmith.
Do I still need an anti-snap cylinder?
Yes. West Yorkshire Police and the Master Locksmiths Association both put a TS 007 3-star or Sold Secure Diamond cylinder ahead of the jammer. A white arm does not stop a snap attack on a weak cylinder. The Association's fitted-cylinder figure, from about £130, is their guide. Get a quote. Do not read it as the price of these packs. None of the accessories here is sold as TS 007 or Diamond.
Will a sash jammer fit an outward-opening door?
It can, if the body sits on the moving sash and the arm still covers the frame. Inward doors take the body on the frame. The screws still have to find steel or a jack nut. Outward doors are also where locksmiths talk about hinge bolts, which are not in this set. A brace is not the outward substitute.
What about French doors with vertical handles?
The hzuisst clamp is for horizontal levers only. Vertical or curved handles will not take it. You are back to sash jammers on the hinged leaves, two per leaf in the Home Secure count for French doors, or a keyed jammer from a locksmith. Do not force the clamp on and hope the button still releases.
Will a DoorJammer fit my back door?
Only if the door opens inward and you can slide a brace into a gap of at least 3 mm with no seal in the way. The maker says most uPVC doors fail that test. Outward doors are excluded. At about £22.72 it is a poor guess for a uPVC threshold. Try the gap with the door shut before you buy, or skip it.
How do I actually lock a multipoint door?
Lift the handle fully so the hooks throw, then turn the key or the thumb-turn. ProtectUK gives that order. Leaving the handle down only latches the door. An extra jammer does not complete a multipoint you forgot to lock. If the handle will not lift, the gearbox needs a locksmith, not another accessory.

Related pages

Best additional door lock

Additional door lock

Extra door lock UK: choose the job before the brand

How to fit a sash jammer without locking yourself out

Portable door lock vs sash jammer, which to use

Sources

Public UK sources used for this page in October 2026. Prices, stars and review counts are the amazon.co.uk figures in this comparison. No lab test was run.

  1. Lichfield District Council, protect your home (retrieved October 2026)
  2. West Yorkshire Police euro-cylinder note (Walton Parish Council PDF) (retrieved October 2026)
  3. The AA, door locks and home insurance (retrieved October 2026)
  4. ProtectUK, security at home (retrieved October 2026)
  5. MLA sash jammers FAQ (retrieved October 2026)
  6. DoorJammer UK FAQ (retrieved October 2026)
  7. Cheshire Fire and Rescue, HMO fastenings (retrieved October 2026)
  8. DASH HMO lock guide 2023 (retrieved October 2026)