DIY GUIDE · HOME REPAIRS & HANDYMAN

How to change a euro cylinder lock and free a stiff lock yourself
Half an hour. €15–€65 for a new cylinder.

Measure the cylinder, buy the right size and security grade, swap it in minutes, and keep the lock running freely.

DIFFICULTY
Easy
part of the job only
TIME
Half an hour
measuring takes longer than the swap; freeing and lubricating a stiff lock is a few minutes
MATERIALS
€15–€65
a basic cylinder at the low end; a high-security, anti-snap cylinder at the top
A PRO CHARGES
€60–€220
typically €110
  • Every step, start to finish
  • Checked October 2026 — sources at the end
  • Honest about when to call a pro

FIRST, THE HONEST ANSWER

Do it yourself, or get a repairer?

Do it yourself if…

  • The door has a euro cylinder — a barrel with a keyhole and one long screw through the edge of the door below the latch
  • You want to change keys, upgrade security, or replace a cylinder that is stiff or worn
  • You can open the door, so you can reach the fixing screw on its edge
  • It is your own home, or your landlord has agreed in writing

Get a pro if…

  • You are locked out, or the key has snapped in the cylinder
  • The multipoint gearbox inside a uPVC or composite door has failed — the handle will not lift or lower
  • It is a mortice lock or a nightlatch you do not know how to change
  • You rent, and the lock is the landlord’s to repair or replace

Safety first

  • Keep the door open and wedged while the cylinder is out, so nobody can be locked out or shut in.
  • Use lubricant sprays in a ventilated space and keep them from your eyes; read the label, as the HSA’s chemicals guidance advises.
  • Choose a thumbturn on the inside of escape doors so everyone can get out fast in a fire without a key.
  • Do not leave a projecting basic cylinder on an external door; it is the easiest point for a break-in.
  • Keep spare keys away from the door and letterbox, where they can be hooked through.

Stop here: Rented homes, failed gearboxes and break-ins

In a rented home, the 2019 rented-housing standards make the landlord responsible for keeping doors and their fittings in good condition and repair, and the local authority enforces them; a whole lockset on an external door is the landlord’s to replace, and a tenant changing locks without agreement risks a dispute. A failed multipoint gearbox or a damaged lock case after a break-in is a locksmith’s repair, because the door’s security depends on it being right. How to hire a lock repairer →

MATERIALCOVERAGEFOR THIS JOB
Replacement euro cylinderMeasured both sides, double, single or thumbturn, rated for securityOne per door
Lock lubricantDry PTFE spray or graphite powderA small can or tube

What size cylinder do you need?

With the cylinder out, measure from the centre of the fixing screw hole, which lines up with the cam, to the outside end — call that A — and then to the inside end — call that B. If A reads 45 mm and B reads 50 mm, you need a 45/50 cylinder, 95 mm in total. Check against the door: once fitted, each end should sit flush with the handle backplate, or stand only a few millimetres proud, so a burglar has nothing to grip.

Makers label sizes outside-first or inside-first differently. Check which way round the shop lists it before you order.

Measure both halves

A euro cylinder is sized as two lengths, one either side of the fixing point, because the two halves are often different — for example 45/50. One lock maker’s guide shows the two measurements taken from the centre of the cam, the rotating part in the middle, to each end. Take the old cylinder out and measure it, rather than guessing from the door thickness.

Single, double or thumbturn

A double cylinder has a key on both sides. A thumbturn cylinder has a key outside and a turning knob inside, which lets anyone inside open the door quickly in an emergency without hunting for a key. A single cylinder is keyed one side only and used where one side needs no access, such as some back gates.

Security grade and anti-snap

Basic cylinders can be snapped or bumped by a burglar. Higher-grade cylinders are built with a sacrificial section that breaks away, leaving the lock still working, and resist picking and bumping. Choose a tested, rated cylinder for an external door. If you also fit a security handle, its thicker backplate needs a longer outside half so the cylinder sits flush.

Sticking key or failing lock

A key that is hard to turn is often only dirt and lack of lubrication, or a door that has dropped so the bolts drag on their keeps. One hardware maker advises lubricating the moving parts of locks with a light, non-acidic mineral oil twice per year. Check the door before you blame the cylinder.

Keyed alike

If you are changing the front and back cylinders together, you can buy them keyed alike so one key opens both. Ask for this when you order; it cannot be done afterwards.

Order a cylinder with at least as many keys as people in the house, and keep the key code card somewhere safe.
On a door with a security handle, measure from the outside face of the handle backplate, not the door.

THE PART THAT DECIDES THE FINISH

Before you start — the door and the lock

Find the card that matches your door. For every swap, keep the door open and wedged so it cannot close and lock you out.

uPVC or composite door with a multipoint lock

A lever handle that you lift to lock, with a cylinder below it and bolts along the edge.

  1. Open the door and wedge it
  2. Find the long fixing screw on the faceplate, level with the lower end of the cylinder
  3. Check the handle lifts and lowers smoothly with the door open — if not, the gearbox is the problem
  4. Have the current key ready
Timber door with a sashlock or deadlock

A cylinder in a lock case mortised into the edge of a timber door.

  1. Open and wedge the door
  2. Remove the screws holding the faceplate on the door edge, if the cylinder screw is hidden behind it
  3. Find the cylinder fixing screw in line with the cylinder
  4. Note how the faceplate and cylinder sit so they go back the same way
Stiff or sticking lock

The key turns hard, or the bolts drag when locking.

  1. Test with the door open: if the key turns freely, the door is dropping onto its keeps
  2. If it is stiff with the door open, the cylinder or lock case needs cleaning and lubricating
  3. Check the key itself for wear or bending; try the spare
  4. Have a dry lock lubricant ready
Rented home

You rent the house or flat.

  1. Read your lease for anything about locks
  2. Tell the landlord in writing what is wrong and ask for the repair or for permission
  3. If you are allowed to change the cylinder, give the landlord a key as agreed
  4. Keep the old cylinder to refit when you leave, if that was the arrangement
Nightlatch or rim lock

A box lock on the inside face of the door with a cylinder through it, often on older timber front doors.

  1. Check whether the cylinder is held by two screws from the inside through a backplate
  2. Measure the door thickness; rim cylinders come with long connecting bars that are cut to length
  3. Note which way the tailbar is cut before you remove the old cylinder
  4. If the lock case itself is loose or broken, replace the whole nightlatch as a matched set

THE JOB

How to change a euro cylinder, in order

  1. Open and wedge the door

    2 min

    Open the door fully and wedge it so it cannot swing shut while the cylinder is out. Lay a cloth on the floor below the lock to catch screws. Have the key, the screwdriver and the new cylinder to hand.

    • Never do this with the door shut — you cannot get the cylinder back in from one side
    • Keep children and pets from closing the door
    • Check the new cylinder’s keys work in it before you start

    Mistake to avoid: Working with the door closed. If the screw or cam jams, you are locked out.

  2. Measure the existing cylinder

    5 min

    Measure from the fixing screw hole to the outside end of the cylinder and to the inside end, either with the cylinder in place for an estimate or, better, once it is out. Note whether it is double, thumbturn or single.

    • Measure to the end of the barrel, not to the end of the key
    • On a security handle, check the outside half sits flush with the handle face
    • Write both figures down

    Mistake to avoid: Buying the cylinder by the door’s thickness. Cylinders are offset, and the wrong split will not lock.

  3. Remove the fixing screw

    5 min

    On a uPVC door, the fixing screw is the larger screw on the faceplate, level with the lower part of the cylinder; on a timber door it may be behind the faceplate. Undo it fully and set it aside. Keep the screwdriver square in the head to avoid stripping it.

    • If the screw is tight, a firm push with the screwdriver stops it slipping
    • Do not remove the other faceplate screws on a uPVC door — they hold the gearbox
    • Keep the screw; it is usually reused

    Mistake to avoid: Undoing the wrong screw on a uPVC faceplate. You loosen the multipoint mechanism instead.

  4. Turn the cam and slide out the cylinder

    5 min

    Put the key in and turn it slightly, a small part of a turn, until the cam inside lines up with the cylinder body. One lock maker describes it as turning the key slightly while pulling. Pull gently on the key and the cylinder will slide out. If it catches, turn the key a little either way and try again.

    • Wiggle the key gently; never force it
    • If the handle is fitted tight, loosening the handle screws a little can help
    • A stuck cylinder with a snapped key is a locksmith’s job

    Mistake to avoid: Hammering or levering the cylinder out. It damages the lock case, which then needs replacing.

  5. Check the new cylinder against the old

    5 min

    Hold the new cylinder beside the old one and check the lengths either side of the cam match, and that it is the same type — double, thumbturn or single. Check that the thumbturn, if it has one, goes on the inside.

    • Set the new cam to line up with the body, using one of the new keys
    • Check the security rating is marked on the cylinder face if you bought a rated one
    • Keep the old cylinder until the new one works

    Mistake to avoid: Fitting a thumbturn cylinder the wrong way round. The turning knob ends up outside.

  6. Fit the new cylinder

    5 min

    With the key in and the cam lined up, slide the new cylinder into the lock case from the side it fits, until the screw hole lines up with the hole in the door edge. Push the fixing screw through and tighten it until it is firm, but do not overtighten.

    • If the screw will not start, the cylinder is not fully home — check the cam
    • Turn the key slightly to help line up the screw hole
    • Firm is enough; an overtightened screw can bend the cylinder

    Mistake to avoid: Leaving the cam sticking out and forcing the cylinder in. The cam jams and the lock will not turn.

  7. Test with the door open, then closed

    5 min

    With the door still open, lock and unlock with the key from both sides, and the thumbturn if there is one. On a multipoint door, lift the handle and turn the key through the full lock. Only when that works smoothly, close the door and test again from inside and outside.

    • Check every key you have been given
    • If it is stiff only with the door closed, the door needs adjusting, not the lock
    • Lubricate the new cylinder lightly before regular use, if the maker allows

    Mistake to avoid: Closing the door before testing. If the new cylinder is wrong, you may be locked out.

  8. Free and lubricate a stiff lock

    10 min

    If the lock is stiff with the door open, spray a little dry PTFE lock lubricant or puff a little graphite into the keyway and work the key in and out and round a few times. Lubricate the latch and the bolts on the door edge with a light oil, and wipe off the excess. If it is stiff only when the door is closed, the door has dropped onto its keeps — adjust the hinges or keeps instead.

    • A light non-acidic oil on the bolts twice a year keeps a multipoint lock smooth
    • Never use cooking oil, grease or a general-purpose spray in the keyway — they gum up
    • If the key itself is worn, cut a new one from the code, not from the worn key

    Mistake to avoid: Forcing a stiff key. Keys bend and snap in the barrel, and a stiff multipoint lock forced repeatedly breaks the gearbox.

The mistakes that make it worse

  • Changing a cylinder with the door closed
  • Buying a cylinder by guessing the size
  • Undoing the wrong screws on a uPVC faceplate
  • Using grease or cooking oil in the keyway
  • Forcing a stiff key until it snaps

Stop here and get a locksmith

  • You are locked out, or a key has snapped in the lock
  • The multipoint gearbox has failed, or the lock case is broken
  • The door is in a rented home and the landlord has not agreed
  • There has been a break-in and the door or frame is damaged
How to hire a lock repairer →

Key hard to turnDirt and no lubricant, or a door dropping onto its keeps. Test with the door open; lubricate the keyway and bolts, or adjust the door.
Cylinder will not come outThe cam is not lined up. Turn the key a little either way while pulling gently; loosen the handle screws if they grip it.
New cylinder will not lockWrong size or the cam is out of line. Check both lengths, line the cam up with the key and refit.
Cylinder sticks out beyond the handleToo long on that side. Swap for a size that sits flush, or nearly flush — a projecting cylinder is easier to snap.
uPVC door handle will not liftThe door has dropped or the gearbox has failed. If it lifts with the door open, adjust the door; if not, the gearbox needs replacing.
Key snapped in the lockDo not try to drill it. If part sticks out, pull it gently with pliers; otherwise call a locksmith.
Thumbturn on the wrong sideThe cylinder was fitted backwards. Remove it and refit it with the thumbturn on the inside.
Lock works but the door rattlesThe keep or the multipoint keeps are too far from the door. Adjust the keeps or the door compression rather than the lock.
New keys stiff in a new cylinderNew keys can have burrs. Work the key in and out a few times with a little dry lubricant, and check you are using the right key for the cylinder.

WHAT YOU SAVE

What it costs to do it yourself

Basic euro cylinder€15
High-security, anti-snap euro cylinder€47–€63
Lock lubricant€7
Total, one door€15–€65
DIY total€15–€65
A lock repairer charges per job
LOW
€60
TYPICAL
€110
HIGH
€220
Lock Repair price guide →

Guide prices compiled by the Locufy team from published Irish and UK provider price lists and 2026/27 cost guides. Updated 2026.

A cylinder swap costs only the cylinder. On an external door, the extra for a high-security, anti-snap cylinder is the best value security upgrade there is.

RATHER NOT?

Lock repairers near you, with prices shown

The ones who cover your area, nearest first, with one score from every review. No account needed to look.

Or post the job free and let them come to you.

Lubricate twice a year

A little lock lubricant in the keyway and light oil on the bolts in spring and autumn keeps the lock running freely.

Keep the key card

Store the key code card safely; it lets you order more keys without the original.

Dispose of the old cylinder and cans properly

An old cylinder is scrap metal and can go to the metal skip at your civic amenity site. Empty or part-used aerosol lubricant cans are hazardous waste and go to the civic amenity site, not the recycling bin, as mywaste.ie explains.

Tell your insurer, if needed

Some house insurance policies set requirements for locks on external doors; check yours and keep the receipt.

Check the other doors

While you have the tools out, check the back door, any side door and the garage door; one weak cylinder undoes a strong front door.

Changing a euro cylinder lock and freeing a stiff lock: questions people ask

Take it out and measure from the centre of the fixing screw hole, in line with the cam, to each end. The two figures, such as 45/50, are the size you order.

A euro cylinder, yes — it takes a screwdriver and a few minutes with the door open. A failed multipoint gearbox or a broken lock case is a locksmith’s job.

Test it with the door open. If it turns freely then, the door has dropped onto its keeps and needs adjusting. If it is still stiff, clean and lubricate the lock with a dry lock lubricant.

A cylinder built to break at a sacrificial point when attacked, leaving the lock working, and to resist picking and bumping. It is worth fitting on every external door.

Ask the landlord in writing first. Under the 2019 rented-housing standards the landlord must keep doors in good repair, and changing locks without agreement can cause a dispute.

On the Locufy price guide for Ireland, lock repair costs €60–€220 per job, typically €110. A cylinder swap is at the low end; a gearbox or a full lock replacement at the top.

MORE GUIDES

More DIY guides

Adjusting a uPVC door or window that drops, drags or will not lockFixing an internal door that sticks, drops or will not latchFixing a window that sticks, will not close or will not stay openHanging pictures and mirrorsRegrouting tilesPainting a roomHanging wallpaperSpray painting small items with aerosol paint
All 90 DIY guides →How to hire a lock repairer →Lock Repair price guide →Lock repairers on Locufy →

Sources — checked October 2026

  1. ERA — how to choose and change your cylinder: measuring from the cam, removing the fixing screw, turning the key while pulling
  2. ERA — how do I maintain my doors: lubricate locks with light non-acidic mineral oil twice per year
  3. HSA — chemicals
  4. Irish Statute Book — S.I. No. 137/2019, Housing (Standards for Rented Houses) Regulations 2019
  5. gov.ie — minimum standards in rented accommodation
  6. MyWaste — what to do with aerosols
  7. diy.ie — euro cylinder locks, price check October 2026
  8. diy.ie — lock lubricant, price check October 2026