European vs. American Forced Entry Standards for Doors and Windows

June 18, 2025 by Samuel Fish

Article Summary

• The State Department SD-STD-01.01 and European EN1627 forced entry standards are the most commonly specified standards for high security doors and windows.
• Both standards are designed to evaluate how long a door or window will resist attack.
• The standards are designed with different target audiences.
• The State Department standard is primarily intended for extremely high-risk government buildings and facilities.
• The EN1627 standard is primarily intended for lower-threat residential and commercial applications.

The two most commonly cited forced entry standards for security doors and windows are the US State Department (DoS) SD.STD-01.01 and the European EN1627. Each standard has various levels of forced entry resistance that can be tested to. On the US side: FE5, FE15, and FE60. On the European side, RC1, RC2, RC3, RC4, RC5, and RC6.

The main difference between the various levels is time. How long will a door or window resist against an attack with a given set of tools and number of attackers? Over the last decade, we’ve tested our Shield Embassy Series and Fortress Series doors and windows to these standards countless times at independent laboratories in Europe and the US. Along the way, we’ve learned a lot about the differences and common mistakes people make when evaluating them.

Overview

The State Department standard is designed and primarily intended for government use, as it sets the requirements for doors and windows used at US embassies and consulates around the world. Testing consists of a team of 6 attackers using mechanical tools such as sledgehammers, axes, battering rams, and wedges. The reason the State Department standard is widely used outside of government applications is because it is the gold standard for testing. There is no other forced entry standard in the world that is more rigorous and difficult to pass than the State Department standard. The European EN1627 standard is primarily designed for residential security because security doors are very common in European homes and apartments. Although the higher levels (RC4, RC5, and RC6) are suitable for high security applications and allow for the use of mechanical tools and some power tools.

The Details

The US State Department standard is significantly more rigorous and difficult to pass, largely due to the number of attackers—six in total. This is meant to simulate a mob attacking a US Embassy in a foreign country. For each level: FE5 (5 minutes), FE15 (15 minutes), and FE60 (60 minutes), the team of attackers focuses on three points: the lock side, the hinge side, and the center of the door. A door must withstand each of the three attack points in order to be certified, and the team cannot pause the clock to evaluate or rest during the test. The total attack time for each level is:

• FE5: 1.5 man hours of attack time (5 minutes on each of the 3 attack points, 6 man team)
• FE15: 4.5 man hours of attack time (15 minutes on each of the 3 attack points, 6 man team)
• FE60: 18 man hours of attack time (60 minutes on each of the 3 attack points, 6 man team)

The European EN 1627 standard is less rigorous than the U.S. State Department’s, but still a reputable benchmark—particularly for residential applications. It involves a single attacker (compared to six in the DoS standard) using a defined set of manual and power tools. We’ll focus on the RC3 (5 minute), RC4 (10 minute), and RC5 (20 minute) levels. One major difference in how time is calculated is the attacker has the ability to “pause” the clock during testing to evaluate and rest between efforts.

• RC3: 5 minutes of attack time/machine time (20 minutes max including pauses and rest)
• RC4: 10 minutes of attack time/machine time (30 minutes max including pauses and rest)
• RC5: 15 minutes of attack time/machine time (40 minutes max including pauses and rest)

To illustrate the differences: while both the State Department FE5 and the European RC3 are considered 5 minute tests, the European RC3 is significantly easier to pass. This is due to the presence of only one attacker and a total of five minutes of active attack or machine time. We’ve seen this first hand over the years based on testing at independent European test laboratories. When testing to RC3, our Embassy Series door needs less internal reinforcement and fewer locking bolts in order to pass the RC3 test compared to the State Department FE5 test. Clients occasionally interchange RC4 and FE15 ratings, assuming they offer similar protection, when in reality the standards differ significantly in testing rigor and threat simulation. The RC4 door must withstand 10 minutes of attack by one individual while the FE15 door must withstand 4.5 man hours of attack time (45 minutes by 6 attackers). Our testing of the Fortress Series door has shown that less internal reinforcement and fewer locking bolts are needed to meet the EN 1627 RC4 standard than to pass the State Department’s FE15 test.