Start with the cylinder. On a uPVC or composite door, the euro cylinder is the component most break-in attempts target, and upgrading it to a TS007 3-star rating closes that route for a fraction of what a new door costs. Then check the frame fixings, the glass and the letterplate, because a strong lock in a weak frame is still a weak door.
In plain terms: a timber door puts you in BS3621 territory, and a uPVC or composite door puts you in TS007 and PAS3621 territory. You cannot fit a BS3621 mortice lock to a uPVC door, and asking for one is a sign the conversation has gone wrong.
One more mark worth recognising. Sold Secure Diamond, sometimes written SS312, is an independent cylinder grade from a separate test body. Many premium cylinders carry both the TS007 Kitemark and the Sold Secure Diamond stamp, and some higher-value insurance policies name Diamond specifically.
TS007 rates euro cylinders and the hardware around them against the attack methods used on domestic front doors: snapping, bumping, picking and drilling. It uses a star rating, and three stars is the level that matters.
Two routes reach three stars.
Take the first route if you have a choice. A single stamped component you can look at is easier to prove to an insurer than a combination that depends on two parts still being the ones that were fitted.
Lock snapping is why this standard exists. It became the dominant method of forced entry on uPVC doors in the UK, and TS007 was developed by the Door and Hardware Federation in response to it. A cylinder with no rating at all, on a door of any material, is the weakest point in most British homes.
Five minutes, no tools. Do this before you buy anything, because you may already comply.
A mortice lock showing only a manufacturer name, with no British Standard reference, is almost certainly not BS3621 compliant. An unmarked euro cylinder carries no rating at all.
That last pair of steps is the one people skip and the one that matters most. The policy defines your requirement, not a salesperson and not this article.
Almost every UK home insurance policy contains a security clause, usually buried in the schedule under a heading like Security or Endorsements. It states the lock standards your external doors must meet.
Typical wording requires a 5-lever mortice deadlock to BS3621 on final exit doors, or a multi-point locking system with a TS007 3-star cylinder. Many policies also require keys to be removed from internal locks when the property is empty.
Why this matters more than any product recommendation: if the locks fitted do not meet the wording, an insurer can reduce or decline a theft claim even on an active policy. That happens, and it happens after the burglary rather than before.
Read the clause. If the wording is ambiguous, ask your insurer in writing and keep the answer. A photograph of each cylinder showing its star marking, kept with your policy documents, costs nothing and settles the question if it is ever asked.
A rating certifies a component, not a complete door. A 3-star cylinder in a frame fixed with short screws into plasterboard is a strong lock on a weak door, and this is the part product-led security advice consistently misses.
Four things decide whether the frame holds.
Fixings into masonry. The frame needs fixing into the structure, at proper intervals, with fixings long enough to reach it. Our fitting guide sets out spacing and fixing specifications, and a door fitted to those is doing what a doorset is supposed to do.
Keep and strike plate fixings. Long screws into the frame timber or reinforcement, not short ones into the plastic profile alone.
Frame material and reinforcement. A leaf that resists attack transfers the load to the frame. Our composite front doors are supplied on a solid timber frame for exactly this reason.
Hinge security. Hinge bolts or security hinges resist attack on the hinge side, which matters on outward-opening doors where the hinge knuckles are accessible.
The honest summary: on most houses the cylinder is the cheapest, fastest and largest single improvement available. The frame is the one that decides whether the improvement holds under attack.
A determined attempt goes around the lock rather than through it. Three components deserve separate attention.
Glazing. Toughened and laminated glass do different jobs. Toughened glass is a safety product that breaks into blunt fragments.
Laminated glass is the security product: an interlayer holds the pane together when it breaks, so the opening does not become a route. If your door has glass near the lock, laminated is the specification to ask for. Our safety glazing guide covers where each is required.
Letterplates. A letterplate is an opening in your door by design. Products tested to TS008 restrict what can pass through it, and a letterplate positioned away from the lock is better than one beside it.
Door viewers and chains. A viewer lets you identify a caller without opening. Neither a viewer nor a chain resists a forced attempt, and both are worth having for a different reason: most domestic security failures are social rather than physical.
PAS24 is the UK test specification for enhanced security performance in doors and windows, and a doorset tested to it has been through third-party forced-entry testing at a UKAS-accredited laboratory. Secured by Design is a separate police accreditation with wider scope. Both are explained in full in our guide to composite doors.
Two practical points about buying one.
PAS24 certifies the complete doorset. Leaf, frame, glazing and hardware were tested together as a system. Change a component afterwards and the certification may no longer describe what is on your wall. Fitting a different handle, adding frame extensions, or replacing the cylinder with an unrated one can all invalidate it. If you are buying a certified doorset, keep it as specified.
Part Q applies to new dwellings, not to replacements. Replacing a front door on an existing house does not require PAS24. Building a new dwelling or converting a building to residential use does. Plenty of homeowners choose PAS24 anyway, for the security rather than the compliance, and that is a reasonable decision.
No material is secure on its own. Security comes from the combination of leaf, frame, glazing and lock, which is why the test standards certify complete doorsets rather than materials.
That said, the materials behave differently under attack.
Any of the four, specified with a rated lock in a properly fixed frame with laminated glass where it matters, gives you a secure front door. An unrated cylinder undoes all four.
