Retrofit reinforcement or a certified security door set
Retrofit reinforcement keeps your existing door and strengthens it. A folded steel sheet clads the door leaf, steel angle profiles protect the door frame, a multipoint lock is fitted, and security pins are added to stop the door being lifted off its hinges. The outside appearance of the door changes, but the original joinery stays in place.
A certified security door set is a complete unit — door leaf, frame, lock and hinges — designed and tested as a whole, then installed in place of the existing door. It is the most effective solution, because its resistance does not depend on the quality of the original structure around it.
The deciding factor is the condition of the door frame and the wall. Retrofit reinforcement fitted to a rotten frame or a hollow partition wall will not deliver what you expect: the force applied during a break-in is transferred to the fixings, and therefore to whatever they are anchored in.
The A2P BP certification
Certified security door sets are measured against the A2P BP certification, issued by CNPP. It has three levels — BP1, BP2 and BP3 — corresponding respectively to five, ten and fifteen minutes of resistance to break-in attempts in standardised tests.
The certification applies to the unit as tested. Swapping the lock on a certified door set for another model, however well regarded, voids the certification, since the configuration is no longer the one that was put through the tests.
Installation matters as much as the product. A BP3 door set poorly anchored in the masonry is no better than an ordinary door. Insist on being given the certification report, and make sure the installation record states the fixing method used.
Adapting reinforcement to the existing building
French housing includes doors that do not call for the same solution: older non-standard joinery, nineteenth-century apartment buildings, post-war estates, individual houses and new developments. The frame, opening direction, walls and building rules determine what is genuinely compatible.
There are two practical consequences. Size first: an off-the-shelf door set stops at standard dimensions, and the door of a canut building or the carriage entrance of an old courtyard almost always calls for made-to-measure fabrication. The substrate second: stone masonry provides excellent anchorage, provided it is worked by someone who knows the material, whereas in post-war buildings it is how well the fixings hold in the concrete and the partition walls that decides what the reinforcement will actually be worth.
In a protected heritage area or near a listed historic monument, altering the outside appearance of a door visible from the public highway may require planning permission and the opinion of France's heritage architect authority (Architecte des Bâtiments de France). Check with your local planning department before starting any work.
What door reinforcement does not do
Reinforcement protects an opening, not a home. If your door becomes the most resistant point, attention will naturally shift to a ground-floor window, a balcony French door, a window onto an inner courtyard or a garage entrance.
Consistency therefore matters more than raw performance. Reinforcing the front door of a ground-floor home whose windows have neither shutters nor break-in-delaying glazing moves the problem rather than solving it.
Finally, reinforcement is no substitute for basic habits: not announcing a long absence on social media, having your post collected, using outdoor lighting, keeping on good terms with the neighbours. These measures cost nothing and count for a great deal.