When you replace a window, hardly anyone asks whether it can resist a break-in. People ask about price, material and insulation. Yet a ground-floor window that faces the street or the garden is, for many homes, the easiest way in. There is a European standard for this, EN 1627, which gives each window a resistance class from RC 1 to RC 6.
This guide explains what those classes mean, what the German crime-prevention police recommend, what should be written in the quote, and what we could not confirm for Portugal. We give no prices: we did not find any in a source we can cite.
What an RC class is
EN 1627 is the standard that defines burglary-resistance classes for windows, doors and facades. «RC» stands for Resistance Class. There are six classes, RC 1 to RC 6, and the higher number is the higher resistance. The earlier pre-standard, valid until September 2011, used the letters WK.
What gets tested is the whole window: frame, hardware and glass together. The list of certified products published by the German police explains that the test is run in conditions close to real use, to make sure the whole construction has no weak point. So the class belongs to the window as it was tested, not to one part on its own.
What each class withstands
The figures below come from a manufacturer’s sheet (Thermosash, July 2022) that summarises EN 1627. We did not read the standard itself, and the sources we found disagree on the lowest class, so we do not describe RC 1 by its tools.
| Class | Tools the test burglar uses | Resistance time | Test time |
|---|---|---|---|
| RC 2 | Simple tools: screwdriver, wedges, pliers | 3 minutes | 15 minutes |
| RC 3 | Two screwdrivers and hand tools: hammer, crowbar, manual drill | 5 minutes | 20 minutes |
| RC 4 | Also saws, axes, chisels and battery tools | 10 minutes | 30 minutes |
| RC 5 | High-performance power tools, such as a drill, reciprocating saw and angle grinder with a disc up to 125 mm | 15 minutes | 40 minutes |
| RC 6 | The same, with an angle grinder disc up to 250 mm | 20 minutes | 50 minutes |
The resistance time is the time the test burglar is actually attacking the window. The test time is the total, including pauses, tool changes and observation. A test is a laboratory simulation: it does not promise that a window will resist for the same time in real life.
The classes RC 1 N, RC 1 and RC 2 N
The German police explain:
- In RC 1 N and RC 1 there is no test with tools. They are a «basic security» for windows fitted high up, for example from the first floor, where the burglar has no ground to stand on and needs help to climb.
- The N (RC 1 N and RC 2 N) means the safety glass is left out. RC 1 has safety glass, but of a lower level than RC 2.
That is why the German police recommend these classes only with limits and advise talking to the local prevention service first. The unreserved recommendation starts at RC 2.
What the German police recommend
The list of «burglar-resistant windows and facades» from the German police crime-prevention commission (January 2025) says that, in new builds and renovations, windows and balcony doors tested to EN 1627 at least at class RC 2 give good protection. It also says the test only counts if the window is fitted properly, following the manufacturer’s instructions, and that handing over an installation certificate should be part of a correct installation. The fitting company is responsible.
This is a recommendation from the police of another country. We did not find an equivalent from the Portuguese PSP, nor a Portuguese rule that requires an RC class in a home.
What we know for Portugal
A Portuguese-language article from idealista says windows and doors have burglary-security classes from 1 to 6, where the higher number is the higher protection. It adds that the choice depends on each home’s needs: a ground-floor window facing the street is usually more exposed than one on a high floor, and windows are only one part of prevention.
We could not confirm:
- whether there is an official Portuguese recommendation by floor;
- whether a Portuguese insurer asks for, or gives a discount for, an RC class (ask yours);
- what it costs on average to go from a normal window to RC 2. Ask the installer for the figure, on a separate line.
What should be in the quote
If you want a burglar-resistant window, say so in your request. Ask the installer in writing for:
- The class you want, for example «RC 2», not just «security window».
- The certificate or test report for the complete unit (frame, hardware and glass). Ask for it in the name of the whole unit, not of one part.
- Confirmation that your model and size are covered by the test. Production is monitored to match the window that was tested.
- Who fits it and how. Fitting follows the manufacturer’s instructions, and the installer hands over an installation certificate.
- The type of glass. Talk to the installer about safety glass and check what is included.
Use the quote checker to see what is missing. If you have doubts about the company, see how to check a company.
A secure window is not enough
The window is only one way in. The front door and the balcony door are entrances too. EN 1627 covers balcony and terrace doors as well, and it is worth thinking about the whole home before spending more on a single item.
Sources
- German police (KPK/Bavarian State Criminal Police Office): Geprüfte und zertifizierte einbruchhemmende Fenster und Fassaden nach DIN EN 1627 (January 2025): six classes, the RC 2 recommendation, the meaning of N and RC 1, installation and installation certificate.
- Thermosash: Resistance Classes According to DIN EN 1627-1630 (July 2022): tools and times per class. A manufacturer’s sheet.
- idealista: windows and doors, security classes 1 to 6: context in Portuguese. It does not cite the standard.
What to do next
- Get an idea of the price with the calculator.
- See the questions for the installer.
- See warranties and certificates.
- If you are replacing old windows, read replacing old windows.