Fit an anti-snap euro cylinder lock

Swap your door's cylinder for an anti-snap version to boost security, matching the size correctly and testing before locking up.

ASL-01Check your door and lock typeLook at the edge of the door where the cylinder sits — most uPVC, composite and many timber doors use a euro profile cylinder held by one screw. If this is a communal front door to flats or a fire door, treat it carefully: Building Regulations Part B require fire doors to close properly and keep their fire rating, so any change to the hardware must not affect that. If in doubt on a shared building, ask the freeholder or managing agent before swapping anything.

RULES

KNOW THE RULES

Fire doors and communal entrance doors in flats are covered by Building Regulations Part B. Changing the lock on a fire door can affect its fire rating — get advice before doing this on a shared or fire-rated door.

ASL-02Measure the existing cylinderWith the door open, unlock and remove the fixing screw on the door edge that holds the cylinder in place, then pull the old cylinder out. Measure both halves separately from the centre screw hole to each end, in mm — most doors are asymmetric (for example 35/45mm), not a matching pair. Keep the old cylinder to hand until the new one is confirmed to fit.

1 each · Tape measure

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ASL-03Buy the right anti-snap cylinderBuy a cylinder in the exact two measurements you took, sold as anti-snap, anti-pick and anti-drill. Look for the TS007 kitemark rating — a 3-star cylinder on its own, or a 1-star cylinder paired with 2-star handles, is what most UK home insurers expect. If you need every door key to work the same key, buy cylinders sold as 'keyed alike' and say so when ordering.

1 each · Anti-snap euro cylinder (TS007 3-star)

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ASL-04Fit the new cylinderProp the door open so you can't lock yourself out, and keep a spare key nearby. Push the new cylinder into the hole with the key slot facing outwards, lining up the cam (the small metal tab) with the slot in the lock mechanism — turn the key gently if it doesn't drop straight in. Refit the fixing screw and tighten it until snug, not overtight.

1 each · Screwdriver (matching the fixing screw head)

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ASL-05Test before you rely on itWith the door still open, test the key from both sides several times, and check the handle lifts and the bolts throw smoothly. Only then close the door and test locking and unlocking from outside, keeping your spare key on you. If the key sticks or the handle feels stiff, loosen the fixing screw slightly and recheck the alignment.

ASL-06Tidy up and store keys safelyDispose of the old cylinder and give all new keys to everyone who needs one, labelling spares clearly. Wipe down the door edge and handle where you were working. Keep one spare key somewhere outside the property in case you're locked out.

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