Choosing the right deadbolt lock is crucial to ensure the effective security of your home or business. Deadbolts provide an additional level of protection, significantly increasing the difficulty for unauthorized individuals to enter. When it comes to deadbolts, there are two main options to consider: single cylinder and double cylinder deadbolts.
This article will explore the differences, benefits, and potential drawbacks of single cylinder and double cylinder deadbolts, empowering you to make an informed decision and effectively safeguard your property.
Key Differences
The key divergence between single-cylinder and double-cylinder deadbolts lies in their locking mechanisms. A single-cylinder deadbolt requires a key on one side for both locking and unlocking, whereas a double-cylinder deadbolt demands a key on both the interior and exterior sides of the door to engage the lock. This fundamental contrast distinguishes these two deadbolt types.
Below is a comparative list highlighting the differences between single and double-cylinder deadbolts:
| Feature | Single Cylinder Deadbolt | Double Cylinder Deadbolt |
|---|---|---|
| Locking Mechanism | Requires a key on the outside and a thumb turn or knob on the inside. | Requires a key on both the outside and inside to lock and unlock. |
| Convenience | Easier and faster to exit in case of an emergency as no key is needed on the inside. | Provides added security but requires a key for both entry and exit, potentially slowing down emergency egress. |
| Security Considerations | Slightly less secure on the inside. | Offers enhanced security as keys are needed on both sides, making it more resistant to break-ins. |
| Recommended Use Cases | Typically used on doors where quick and easy egress is a priority, such as residential front doors. | Recommended for doors with glass panels or windows near the deadbolt. Also suitable for commercial properties and high-security applications. |
| Code and Regulations | Often complies with building codes and regulations for residential properties. | May not be permitted in some residential areas. May be required by building codes for specific commercial applications. |
What is a Double Cylinder Deadbolt?
In the preceding section, we examined the fundamental distinctions between single and double key deadbolts. To gain a more detailed understanding, let’s delve deeper into the specifics of a double-cylinder deadbolt and explore its advantages and disadvantages.
Overview of the Double Cylinder Deadbolt:
A double-cylinder deadbolt is a lockset distinguished by two key-operated knobs, deviating from the conventional single-knob and thumbturn combination. In this lockset, two keys are necessary for operation—one inserted into the interior knob and the other into the exterior knob. Unlocking the mechanism requires both keys to be simultaneously turned in the same direction, involving the collaboration of two individuals to operate the lockset.
Pros and Cons of Double Cylinder Deadbolt:
Pros:
- Enhanced Break-In Protection: Double cylinder deadbolts significantly heighten security by requiring keys on both the interior and exterior sides of the door. This design notably reduces the risk of unauthorized access by burglars, particularly effective on doors with adjacent glass panels or windows where the absence of a thumb turn on the interior side makes it challenging for intruders to manipulate the lock.
- Occupant Safety Inside the Home: The double-cylinder deadbolt not only enhances security but also ensures the safety of individuals within the premises. This is particularly valuable for households with young children or elderly family members with dementia, as the requirement for two keys to unlock prevents a single person from exiting independently.
Cons:
- Safety Concerns in Emergencies: During emergencies such as fires, evacuation may be delayed since both keys are needed to unlock the door. Some building codes restrict the use of double-cylinder deadbolts in residential settings due to these safety concerns.
- Inconvenience in Daily Use: Daily use can be less convenient compared to single-cylinder deadbolts because a key is always required for entry and exit from both sides.
- Potential Lockouts: Forgetting or misplacing keys can result in being locked out of your own property, causing frustration and potential time wastage.
What is a Single Cylinder Deadbolt?
Now that we’ve covered the details of the double-cylinder deadbolt, let’s shift our focus to the intricacies of the single-key door lock.
Overview of the Single Cylinder Deadbolt:
A single-cylinder deadbolt is a commonly employed door lock in both residential and commercial settings. It features a key-operated cylinder on the exterior of the door and a thumb turn or knob on the interior. This configuration allows for locking and unlocking with a key from the outside and the convenience of turning the thumb turn or knob from the inside to secure or release the lock.
Pros and Cons of the Single Cylinder Deadbolt:
Pros:
- Convenience: Single-cylinder deadbolts offer convenience by enabling easy locking and unlocking from the inside using a simple thumb turn or knob, eliminating the need for a key for a swift exit.
- Simplicity: Operating single-cylinder deadbolts is straightforward, making them user-friendly for individuals of all ages, including children and the elderly.
- Affordability: They are often more cost-effective than double-cylinder deadbolts, presenting an economical choice for many homeowners.
Cons:
- Security Vulnerability: A single-cylinder deadbolt may provide less security compared to other lock types. For instance, a potential intruder could attempt to break a nearby window and then reach inside to manipulate the thumb turn, unlocking the door.
Single vs. Double Key Deadbolts: Practical Applications
In this section, we will examine various scenarios to illustrate the practical uses of single and double-key deadbolts.
- Everyday Home Use: For everyday residential use, single-key deadbolts are the most common choice. They offer ease of use and a basic level of security. With a simple turn of the thumb turn, you can quickly lock and unlock the door from the inside.
- Exterior Doors with Glass Panels: If your door features glass panels or sidelights, opting for a double-key deadbolt might be more prudent. This choice helps prevent burglars from breaking the glass and reaching in to unlock the door.
- Minimal Security Needs Location: In low-crime areas or situations where convenience takes precedence over maximum security, single-key deadbolts are ideal for everyday residential use. They provide user-friendly access and sufficient protection in locations with minimal security needs.
- Security in Vulnerable Locations: For homes situated in high-crime areas or those with a history of break-ins, a double-key deadbolt can offer enhanced security. Criminals won’t easily reach inside to unlock the door, providing an additional layer of protection.
- Property with Multiple Entry Points: Securing homes with multiple entry doors can involve the use of double-key deadbolts on less frequently used doors, while doors used regularly for convenience may have single-key deadbolts.
- Emergency Exit: In emergencies, such as fires or the need for a quick exit, the thumb-turn on a single-key deadbolt allows for swift egress without the need for a key.
- Businesses and Commercial Properties: Small businesses, offices, or storage areas within commercial properties may choose double-key deadbolts for added security during non-business hours.
Tip: Which Grade Lock is Best?
Deadbolt locks are classified into three grades by the American National Standards Institute (ANSI) to denote their security levels, with Grade 1 being the highest and Grade 3 offering the least security.
Grade 1 Deadbolt Locks: Considered “commercial grade,” Grade 1 deadbolt locks are well-suited for high-security applications, often employed in business buildings. These locks must meet stringent standards, including enduring 250,000 open/close cycles, featuring a one-inch bolt extending into the door frame, and withstanding 10 hammer blows of 75 pounds of force without failure.
Grade 2 Deadbolt Locks: Also categorized as “commercial grade,” Grade 2 deadbolt locks are typically priced at a mid-level point. While commonly used in residential properties, they undergo less rigorous testing than Grade 1 locks. Grade 2 deadbolts provide a balanced combination of security and cost-effectiveness.
Grade 3 Deadbolt Locks: The lowest grade of deadbolt locks, Grade 3 locks carry the lowest security rating. They only need to withstand two strikes of force and are often employed as secondary security measures on doors, particularly in residential settings.
How to Choose:
High-Traffic Business Areas: Opt for an ANSI Grade 1 deadbolt lock for places with heavy foot traffic within your business. These locks offer the highest level of security and durability, making them suitable for areas where security is a top priority.
Lower Foot Traffic and Residential Use: Consider an ANSI Grade 2 deadbolt lock for areas with lower foot traffic and residential applications. Striking a balance between security and affordability, Grade 2 deadbolts are suitable for less frequented business spaces and residential settings.
Grade 3 Deadbolt Locks: Classified as lower-grade compared to Grade 1 and Grade 2, Grade 3 deadbolt locks provide basic security and are commonly used in less critical applications or as secondary security measures.
FAQs
1. Are double cylinder deadbolts legal?
The legality of double cylinder deadbolts may be subject to restrictions in certain areas due to safety concerns. These locks, requiring a key for both entry and exit, could potentially hinder quick egress during emergencies such as fires. Local building codes often limit their application on main entrance doors in residential settings to prioritize safety. It is essential to consult with local authorities or building departments to understand specific rules governing the use of double cylinder deadbolts.
2. Is a double cylinder deadbolt better than a single?
Whether a double cylinder deadbolt is superior to a single cylinder deadbolt depends on individual security needs, comfort with safety trade-offs, and adherence to local regulations. Many homeowners choose a combination of both types, employing double cylinder deadbolts on doors that require heightened security and opting for single cylinder deadbolts on doors used for everyday convenience and safety.
3. Why use a double keyed deadbolt?
A double keyed (double cylinder) deadbolt is selected for enhanced security. Requiring a key for both locking and unlocking from both inside and outside, it offers increased resistance to unauthorized entry. This type of deadbolt is often favored for high-risk areas, effectively preventing unauthorized access and maintaining key consistency.
Conclusion
The decision between a single cylinder and a double cylinder deadbolt hinges on your specific security requirements, convenience preferences, and safety considerations.
Single cylinder deadbolts are known for their user-friendly nature and are commonly favored in residential settings where a swift and easy exit during emergencies is paramount. Conversely, double cylinder deadbolts add an extra layer of security by necessitating a key for both locking and unlocking the door, both from the inside and outside. Whether opting for a single or double cylinder deadbolt, seeking guidance from a professional locksmith is a wise practice to ensure proper installation.