Under the European standard EN 1627, a window is classified from RC1 to RC6 by how long it resists a defined manual attack with defined tools, and the class belongs to the tested assembly - frame, glass, hardware and installation - not to a frame brand or a lock alone. No window is burglar-proof, and I do not claim a US equivalent for these classes.
If you are a homeowner or architect who has seen "RC2" in a European spec, this is what it means and what it does not. I keep it at the level of the classification system, because the full standard text is behind a paywall and the class for your window lives on a test report for that exact assembly.
What do RC1 to RC6 mean on European security windows?
The classes run from RC1 (lowest) to RC6 (highest), and each step assumes a more capable attacker with more tools and a longer attack. The table shows how published summaries of EN 1627 and EN 1630 typically describe them; the classification itself is on the standard, and I do not read it as a promise for any specific window.
| Class | Typically described attacker and tools | Tool-contact time | Total test time |
|---|---|---|---|
| RC1 | Occasional opportunist, physical force only (kicking, shoulder charge, pulling), no tools | Not listed in the summaries I used | Not listed in the summaries I used |
| RC2 | Screwdriver, pliers, wedge | 3 min | 15 min |
| RC3 | Adds a second screwdriver and a crowbar | 5 min | 20 min |
| RC4 | Experienced attacker; adds saws, impact tools (axe, chisel, hammer) and a battery drill | 10 min | 30 min |
| RC5 | Adds power tools (drill, jigsaw or reciprocating saw, angle grinder) | 15 min | 40 min |
| RC6 | More powerful versions of the RC5 tools | 20 min | 50 min |
In those summaries, tool-contact time is the working impact time of the tester, and total test time includes pauses, tool changes and observation. Variants labeled RC1 N and RC2 N exist without a glazing requirement. The standard does not directly cover the resistance of locks and cylinders to attack with picking tools.
Is a burglar-proof window possible?
No. The classes express how long a window resists a specified attack with specified tools, not that it cannot be defeated.
Position matters as much as class. Tilt on a tilt-turn window is a ventilation position, not an unattended-security setting, so a tilted sash does not keep anyone out. Close and lock the sash when you leave. The same hardware is explained in European tilt-and-turn hardware.
How is a burglar-resistant window tested?
EN 1627 sets requirements and the classification, and three test methods feed it. The 2021 editions are:
- EN 1627: Requirements and classification for windows, doorsets, curtain walling, grilles and shutters, including turning, tilting, sliding and non-openable constructions.
- EN 1628: Test method for resistance under static loading.
- EN 1629: Test method for resistance under dynamic loading.
- EN 1630: Test method for manual burglary attempts, which covers vulnerable areas that the static and dynamic tests do not assess adequately.
What makes a window RC2 - the frame, the lock or the glass?
It is the whole assembly, and no single part earns the class alone. A rated window combines three things:
- Frame and sash: the profiles and corner joints have to hold under the test loads.
- Multipoint hardware: locking points with security strikers or cams around the sash. A multipoint lock is one component, and security classes such as RC2 are rated on the whole hardware set.
- Glass: laminated security glass tested to EN 356 is a component of the assembly, because break-in resistance of glass is regulated separately from the frame.
The practical result is that a stronger lock on an ordinary window does not make it RC2, and an RC2 frame with ordinary glass is not the tested assembly.
Which European window systems list RC2 or RC3?
Eight of the systems and configurations I source list RC values, and I write "lists" or "published up to" because a listing is not a test report for your window. RC3 appears only where the provider data lists it.
| System | Stated by the provider | Note |
|---|---|---|
| MasterLine 8 | RC2 and RC3 variants | Variants, not every window |
| Slim-profile aluminum system | RC2 | Aluminum, narrow sightline family |
| MB-79N | RC1 to RC3 | Confirm per assembly |
| MB-86 | Up to RC4 | Confirm per assembly |
| Genesis 75 | Up to RC3 | Confirm per assembly |
| MaxLight | RC2 | Confirm per assembly |
| Clad Hidden Sash (aluminum-clad wood) | RC2 configurations available for review | Configurations, not a standing rating |
| Clad Passive (aluminum-clad wood) | RC1 and RC2 configurations depending on the assembly | Configurations, not a standing rating |
For any wood, aluminum-clad or uPVC line not listed above, the class is confirmed per assembly. A system that lists multipoint locking without an RC value, such as the MB-79N CSF slim-frame casement, does not carry a class from that listing. How the locking points are fixed into a timber frame is in tilt and turn wood windows and their locks.
Does an RC class mean the window is certified for US security or code?
No. RC classes are European, and I do not state any US burglary certification for these windows. For Clad Hidden Sash, the product notes say plainly that European Rw and RC2 classifications cannot be substituted for US acoustic, impact or structural ratings. I apply the same caution to every aluminum-clad line. An RC class says nothing about those ratings, and it is not an impact rating either.
What about doors and ground-floor sliding doors?
Two sliding door systems list RC2, the Hi-Finity sliding system and the MasterPatio lift-and-slide system, and entry doors are covered with the door itself.
- Sliding doors: both of those systems list RC2.
- Entry doors: see European aluminum entry doors, where security is covered with the door.
What do I ask my supplier to confirm?
Ask for the class on the exact assembly you are buying, in writing. Five questions cover it:
- Which RC class applies to this exact frame, glass and hardware combination?
- Is there a test report or certificate for that configuration, and can I see it?
- What is the glass build, and is it laminated to the tested specification?
- What installation requirements go with the class?
- What maximum size does the test cover?
Send me the window schedule through the quote form and I will ask the system provider those questions for your configuration.
FAQ
What is the difference between RC2 and RC3? RC2 is typically described as defeating an attacker with a screwdriver, pliers and wedge, and RC3 adds a second screwdriver and a crowbar and a longer test time. The table above lists the published minutes.
Is an RC2 window burglar-proof? No. RC2 means the tested assembly resisted a defined attack with defined tools for a defined time, nothing more.
Do tilted European windows keep burglars out? No. Tilt is a ventilation position, so close and lock the sash when the house is unattended.
Do you state a US certification for these windows? No. I make no US burglary certification claim, and a European class is not a US rating. Confirm the report for your exact assembly.
Does the lock alone make a window RC2? No. The class is given to the tested assembly, and the lock is one part of the hardware set within it.