Can my door be breached?
Can my door be breached?
We have all seen the videos and movies of police using a battering ram to break a door open. We kind of think there is no way to stop the police or bad guys from knocking down our doors. Is this true? Lets look at the physics behind door breaching, battering rams and kicking in a door.
The Physics Behind Door Breaching: Kicks and Battering Rams
Breaking down doors has long been a staple in military, law enforcement, and even emergency response scenarios. While it may look simple on screen, the reality involves a lot of physics. Understanding the force required, the role of mass, velocity, and the structure of both the door and the breaching tool reveals just how complex door breaching can be. Here, we’ll explore the physics involved in two common methods: kicking in a door and using a battering ram.
Force and Momentum: The Basics of Door Breaching
When someone attempts to break down a door, they rely on force to overcome the structural resistance of the door and its frame. Force is essentially the rate at which momentum changes during the impact. Momentum is given by the formula:
where m is mass, and v is velocity. For an effective door breach, the mass of the person or object delivering the impact and the speed of the strike must generate enough force to break or displace the door. Newton’s second law gives us the fundamental relationship between force, mass, and acceleration:
This means that the force F exerted depends on how quickly the momentum Δp changes over time Δt. The shorter the impact time, the greater the force produced, making speed and directness critical for successful door breaching.
Kicking in a Door: The Physics and Limitations
When a person attempts to kick in a door, they rely on the mass of their leg, the velocity of the kick, and the support of their core strength to direct the force towards a single point on the door. The force generated by a kick can be many times greater than the person’s body weight, thanks to the dynamics of the motion. Studies on martial artists have shown that a powerful front kick can reach speeds of about 10 m/s and generate forces over 2,000 Newtons (N), or approximately 204 kilograms-force (kgf). For a trained martial artist weighing around 80 kg, this translates to a kick force well over twice their body weight.
For an average person, let’s assume a kick speed of about 5 m/s and a leg mass of approximately 8 kg (about 10% of body mass). Using momentum:
Assuming an impact time Δt of 0.1 seconds, the resulting force F is:
This force of about 40.8 kilograms-force may be sufficient to kick in a standard residential door, especially if applied near the lock, where the door is weakest. However, reinforced or commercial doors may require much higher forces, and even a trained individual might struggle without specific techniques or additional tools.
For a trained martial artist with a faster kick (up to 10 m/s), the force would increase significantly:
This is enough—about 81.6 kilograms-force—to severely weaken or break many standard door frames, but it may still fall short with reinforced doors.
The Battering Ram: Boosting Breaching Power with Mass
A battering ram allows for a much higher impact force by combining greater mass with controlled motion. A typical battering ram weighs around 10–20 kg, with advanced versions reaching 30 kg or more. The person wielding it can achieve speeds of around 4–6 m/s, depending on strength and control.
For an average user with a 10 kg ram moving at 4 m/s, we can calculate the momentum:
With a similarly short impact time of 0.1 seconds, the force exerted becomes:
However, a well-trained or stronger individual using a heavier 20 kg battering ram and achieving a speed of 6 m/s could deliver much greater force
This level of force—around 122.4 kilograms-force— is significantly higher than a kick and can easily breach many residential doors, even those with some reinforcements. When force is applied by a battering ram, it often strikes across a broader area than a foot, distributing force more evenly, which can weaken the door’s structure and make the breach more efficient.
Structural Weaknesses: Where to Apply Force
Both methods benefit from aiming force at weak points. The best location is generally near the lock or latch, where the door is held shut. For single kicks, targeting near the lock can concentrate enough force to break the door free. With battering rams, the heavy, even force can target various weak points along the door frame or hinges to leverage breaks in the structure.
The Role of Material and Reinforcement in Door Breaching
The composition of the door is another factor.
Doors are usually made to be as light as possible to allow easy opening and closing. The more solid the door, usually the stronger it will be.
Solid-core or metal doors are much harder to breach than hollow-core doors, commonly used in residential buildings. Reinforced steel or fiberglass doors, often found in commercial or high-security locations, are designed to withstand higher levels of force and may require specialized breaching tools or several strikes.
Hardwood frames, and thicker door frames also play an important role in a doors’ strength.
When trying to breach a solid-core or reinforced door, even with a battering ram, it may be necessary to deliver multiple impacts to weaken the door frame or internal structure. Each impact causes slight deformations, and over repeated blows, the cumulative effect may lead to failure.
Physics in Practice
The physics of door breaching shows that success depends on the mass, velocity, and skill behind the force delivered, as well as the construction of the door. An average person may struggle with a single kick on a well-built door, while a strong individual or a battering ram can produce enough force to break through. Understanding the momentum, force, and the weak points of a door highlights why battering rams and trained techniques are commonly employed by professionals in door breaching.
What can my door withstand?
The appropriate lock on a domestic door can withstand more then 400kg of force.
A properly fitted deadlock or deadlatch is one of the best ways to add more strength to your door. A deadlatch such as the Lockwood 001 is one of the best deadlocks we have tested, which took us 465kg of force to break open.
The door frame plays a critical role in security your door. Our tests show that having a door frame that is at least 35mm thick is one of the best ways to make your door harder to force open. Our tests show that even a thick pine frame is better then a thin hardwood frame.
The gap between the door and the frame should be as small as possible. Having a large gap gives most locks a point of leverage and more of a chance for the latch or bolt to bend.
Get an expert analysis
If you would like an analysis of your doors to know what they are likely to withstand, give us a call. We can give you an account of how much force we believe your particular door can withstand if it were to be forced or kicked in. We can let you know what the best types of locks or deadlocks are for your door. We can let you know if your door frames are up to the task.
The advise we give is based on both real world experience and the testing of many different doors, door frames and locks.
Do not leave it to chance. Get the knowledge you need to protect your home or business.
The Lock Mob locksmith Toowong are a Brisbane based locksmith and security advisors. Contact us for any locks, key and security problem you may have.
Disclaimer: We are not physicists and we can not accurately predict the force of every type of break and enter. Use this document as a guide only and consult a professional locksmith and security adviser for advice on your security. If you do see any error in our calculations leave a comment and let us know. There are many types of break and enter techniques not discussed in this article. Forcing techniques include opening a door with a crowbar or wedge type device and door spreaders. These types of techniques require specialised doors and frames to prevent forcing.
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