The short answer
Most uPVC and composite doors in the UK take a euro cylinder. It comes in three types: key both sides, thumb turn (key outside, turn knob inside) and half (key on one side only). Timber front doors with a Yale-type night latch use a rim cylinder instead. Whichever type you need, choose one rated TS007 3-star.
A cylinder is the part of a lock that the key goes into. Change the cylinder and you change the key, and on most modern doors you can do it yourself in about 10 minutes without touching the rest of the lock. This guide explains the cylinder types used on UK homes, how to tell which one you have, and which suits your door.
Euro Cylinders: the Standard on uPVC and Composite Doors
A euro cylinder has a round top where the key goes and a narrower section underneath. It slides through the door and the multipoint lock, and it's held in place by one long fixing screw on the edge of the door. Euro cylinders are used on almost all uPVC, composite, aluminium and patio doors, and on many newer timber doors with a sashlock.
Euro cylinders come in three types. Over the last 12 months, about 64% of the euro cylinders we sold online were key both sides, about 35% were thumb turn, and half cylinders were under 1%.
Key both sides
You need a key to lock and unlock from inside and outside. This is the most common type. It's the best choice when there's glass within arm's reach of the lock, because nobody can break the glass and reach in to open the door. The downside is that you need the key to get out, so keep it somewhere close to the door, out of sight and out of reach from the letterbox.
Thumb turn
There's a key on the outside and a turn knob on the inside, so you can lock and unlock from inside without a key. It's quicker to get out in an emergency, and there's no key to lose or leave in the door. Avoid a thumb turn if there's glass or a letterbox close enough to reach the knob.
Half cylinder
A half cylinder has a key on one side only, with nothing on the other. It's used where the lock only needs operating from one side, such as garage doors, gates, communal doors and some key switches.
Rim Cylinders (Night Latch Cylinders)
A rim cylinder is the round cylinder used with a night latch, the traditional "Yale-type" lock on many timber front doors. It sits in a round hole through the door, with a flat bar at the back that turns the latch. It's held on from the inside by connecting screws, not a screw on the edge of the door. If your door has a night latch, a euro cylinder won't fit. You need a rim cylinder, or a new night latch.
Oval Cylinders
Oval cylinders look like a euro cylinder with a smooth oval body instead of the stepped euro shape. They're found on some older doors and locks. If yours is oval, a euro cylinder won't fit the hole. Bring it to our counter or email us a photo and we'll tell you the options.
How to Tell Which Cylinder You Have
| What you see | What it is |
|---|---|
| Keyhole in a round-topped cylinder through a lever handle, with a long screw on the door edge in line with it | Euro cylinder |
| Key outside, turn knob inside | Thumb turn euro cylinder |
| Key on one side, nothing on the other | Half euro cylinder |
| Round brass or chrome keyhole above a latch box on the inside of a timber door | Rim cylinder (night latch) |
| Smooth oval body, no step | Oval cylinder |
Which Is Most Secure?
The type matters less than the rating. Older euro cylinders have a weak point at the fixing screw, and a burglar can snap them there. A TS007 3-star cylinder is tested against snapping, drilling and picking, and gives full protection on its own, without a security handle. Read what TS007 3-star means.
- Our recommendation: Avocet ABS, available as key both sides, thumb turn, half and rim.
- Lower-cost 3-star option: Yale Platinum and the Yale Platinum thumb turn.
- One key for every door: a keyed alike set can mix key both sides, thumb turn, half and rim cylinders on one key.
Next Steps: Measure, Then Fit
- Measure your euro cylinder from the centre of the fixing screw to each end: see how to measure a euro cylinder.
- Choose your type and size from our euro cylinders, or night latches and rim cylinders.
- Fit it with a screwdriver: see how to change a euro cylinder lock.
Not sure what you've got? Email a photo of your lock and the edge of your door to info@homesecureshop.co.uk, call 0151 521 8089, or bring your old cylinder to our trade counter in Aintree, Liverpool.
