Securing Double Entry Doors with Mortise Locks: A Comprehensive Guide

Published: Jan 13, 2026

You have a solid deadbolt on your front door. It’s heavy, made of steel, and when you turn that key, you feel secure. But what if the biggest threat to your home’s security isn’t a brute-force attack, but a key you handed out months ago?

Think about it. Who has a copy of your key? The dog walker? The contractor from last summer’s remodel? A previous tenant?

This is the blind spot most standard locks have, and it’s where the conversation about true home security begins. It’s not just about stopping a lock from being smashed; it’s about controlling who has the power to open it. This guide will walk you through what makes a high-security lock different, moving beyond simple strength to the intelligent features that protect you from modern threats like lock picking, bumping, and unauthorized key duplication.

Foundation: The Anatomy of Security

Before we dive into advanced features, let's get on the same page about what’s happening inside your lock. Most homeowners interact with the key and the thumbturn, but the real magic happens within the lock cylinder.

Think of the cylinder as the lock's brain. It's the part where you insert your key, and it contains a series of tiny pins. When the correct key is inserted, its unique pattern of cuts lifts these pins to a perfect line, allowing the cylinder to turn and unlock the door.

A high-security cylinder enhances this basic design with specialized components designed to outsmart attackers.

The Cylinder: The housing for all the internal parts. In a high-security lock, this is fortified with hardened steel to resist drilling.
Pins & Tumblers: The small, spring-loaded pins that the key aligns. High-security locks use special "security pins" that are designed to trick and trap a lock picker's tools.
The Keyway: The shape of the keyhole itself. Complex and paracentric (warded) keyways make it extremely difficult to insert and manipulate picking tools.
Key Control: This refers to the system that governs who can make copies of your key. This is a feature of the key and the lock system, not just the physical hardware.

Building: Decoding High-Security Features

So, what separates a $30 deadbolt from a $200 high-security cylinder? It comes down to three pillars of protection: physical strength, mechanical complexity, and key control.

Physical Strength: Resisting Brute Force

Most burglars are opportunists, not master thieves. They’re more likely to use force than finesse. This is where industry ratings come into play.

ANSI/BHMA Grades: The American National Standards Institute assigns locks a grade from 1 to 3 based on their durability, strength, and life cycle. Grade 1 is the highest commercial rating, meaning it can withstand a significant amount of force (like multiple hammer strikes) and has been tested for hundreds of thousands of cycles. While a Grade 1 deadbolt is a great start, it doesn’t automatically make it "high-security."
UL 437 Rating: This is the gold standard for security testing from Underwriters Laboratories. A lock with a UL 437 rating has survived an exhaustive battery of expert attacks, including picking, drilling, prying, bumping, and impressioning for over five minutes. It’s like a car’s five-star safety rating—a third-party verification of its protective capabilities.

Building: Decoding High-Security Features

High-security locks achieve this strength with features like hardened steel inserts that shatter drill bits and reinforced construction that resists prying and impact.

Mechanical Complexity: Outsmarting Skilled Attacks

While lock picking isn't the most common burglary method, the vulnerabilities that allow for picking also allow for faster, simpler techniques like "bumping." Lock bumping uses a specially cut "bump key" to jolt the pins into alignment for a brief moment, allowing the lock to open.

High-security locks combat these threats with layers of internal complexity:

Security Pins: Standard pins are flat on top. Security pins come in shapes like spools (thinner in the middle) or serrated (grooved). When a picking tool pushes on them, they get snagged inside the cylinder, giving the illusion that the lock is picked—a "false set" that traps the tool and prevents opening.
Sidebars and Secondary Locking Mechanisms: Some high-security locks, like those from Medeco or Mul-T-Lock, have a completely separate locking mechanism. In addition to lifting the pins to the right height, the key must also rotate them or engage a "sidebar" that runs the length of the cylinder. This is like having to solve two different puzzles at once.

Key Control: The Most Overlooked Feature

This is arguably the most important feature for a homeowner. Key control is the regulation of who can make a copy of your key. Standard keys can be duplicated at any hardware store or kiosk in minutes, meaning every key you hand out is a potential security risk.

High-security locks solve this in two ways:

Restricted Keys: These are keys with a unique keyway design that is not available in public retail. Duplicates can only be made by authorized locksmiths after verifying your identity against a signature card.
Patented Keys: This is the highest level of key control. The key design itself is legally protected by a utility patent. This makes it illegal for anyone other than the original manufacturer to produce the key blanks. When you want a copy, you must go through a strict, documented procedure with an authorized dealer.

For anyone who has service providers, tenants, or family members needing access, patented key control ensures you know exactly how many keys to your home exist and who has them. If a key is lost, you don't have to worry about it being duplicated; you simply need to consider a lock rekeying service to reset the lock to a new key.

Mastery: How to Choose the Right High-Security Lock

You don’t need the same security as a bank, but you deserve better than a basic deadbolt. Choosing the right lock is about matching the features to your specific needs.

Ask yourself these questions:

Mastery: How to Choose the Right High-Security Lock

Who needs access to my home? If you frequently give out keys to others (cleaners, contractors, dog walkers), then patented key control (found in brands like Medeco, Mul-T-Lock, and Schlage Primus) should be your top priority.
What is my neighborhood's risk level? While every home deserves good security, homes in areas with higher property crime rates may benefit more from UL 437-rated cylinders that resist a wider variety of forced entry techniques.
What is the condition of my door and frame? The most advanced lock in the world won't help if your door frame is weak. We'll cover this next.
Do I want convenience features? High-security doesn't mean old-fashioned. Many high-security cylinders can be integrated into master key systems or combined with smart locks for the ultimate blend of protection and convenience. If you're considering this path, exploring a smart lock installation with a high-security mechanical override is a great option.

Action: Beyond the Lock - A Holistic Approach

A high-security lock is a critical investment, but it’s only one part of your home’s security system. To get the most out of your upgrade, you must address the entire door assembly.

Reinforce the Strike Plate: The strike plate is the metal plate on the door frame where the deadbolt extends. Most are installed with short, 3/4-inch screws that only bite into the thin door jamb. Replace these with 3-inch screws that anchor the strike plate directly to the solid wood stud of your home’s frame. This simple, inexpensive upgrade massively increases resistance to being kicked in.
Check Your Door: A hollow-core door offers little protection. Ensure your exterior doors are solid-core wood or metal-clad.
Professional Installation: A high-security lock has tight tolerances. Improper installation can negate its security features or cause it to wear out prematurely. A professional lock installation ensures every component is perfectly aligned and functions as designed.

Frequently Asked Questions (FAQ)

Are high-security locks really worth the extra cost?

It depends on your security goals. If your primary concern is controlling key duplication and protecting against common forced entry methods like drilling and bumping, then yes. The peace of mind that comes from knowing exactly who has access to your home is invaluable for many.

What is the difference between an ANSI Grade 1 lock and a true high-security lock?

ANSI Grade 1 refers only to physical durability and strength against brute force. A UL 437-rated high-security lock is also tested against covert and surreptitious attacks like picking and bypassing. Furthermore, many Grade 1 locks have no key control, which is a core feature of high-security systems.

Can high-security locks still be picked?

With enough time, skill, and specialized tools, almost any lock can be picked. However, the goal of a high-security lock is to make this process so time-consuming, difficult, and noisy that it's not a practical method of entry for a real-world burglar. The layers of security pins, sidebars, and complex keyways are designed to defeat all but the most elite, dedicated experts.

Myth Buster: "If I have a high-security lock, my home is impenetrable."

A lock is just one layer of security. Windows, sliding glass doors, and even the door frame itself are all potential points of failure. A high-security lock is the strongest link in your entryway's chain of security, but it's essential to ensure the other links are strong, too.

Your First Step to Smarter Security

Upgrading your home security from a standard deadbolt to a high-security cylinder is a significant step toward gaining control and peace of mind. By understanding what makes these locks different—their physical resilience, mechanical complexity, and, most importantly, their ability to control who can copy your key—you are empowered to make a truly informed decision.

If you’re ready to explore your options or want an expert assessment of your home's unique security needs, the team at Sure Lock & Key is here to help. Our family has been in the security business for over 35 years, and our licensed technicians can help you choose and install the right solution. When you're ready to secure what matters most, consult with a security professional who puts education and your safety first.