Choosing the Right Deadbolt Configuration for Your Doors
Single- and double-cylinder deadbolts create different key-control and egress tradeoffs. Glass location is only one factor; occupancy, door use, accessibility, emergency escape, tenancy or condominium rules, and applicable Ontario requirements also matter.
Single Cylinder Deadbolts (The Standard)
- Design: Keyed on the outside, features a thumbturn latch on the inside.
- Pros: Easy to lock and unlock from the inside during emergencies. No key is needed to exit.
- Cons: If there is glass within arm’s reach of the door, a burglar can smash the pane and reach inside to turn the thumbturn.
Double Cylinder Deadbolts
- Design: Keyed on both the outside and inside. A key is required to lock and unlock from both sides.
- Tradeoff: Requiring an interior key may reduce one reach-through path, but other entry methods remain and leaving the key nearby changes that benefit.
- Egress concern: A missing key can delay escape during a fire or other emergency. Do not install one on a required exit based on generic advice; confirm the approved configuration with the property authority and an appropriate Ontario building/fire-code professional.
The safety question
A double-cylinder lock needs a key to open from inside. That helps when there is glass near the lock, but it can trap people during a fire or emergency.
Alternatives
Use laminated glass or a security film next to the door, place a single-cylinder deadbolt out of reach of the glass or fit a keyed lock with a key kept near the door where codes allow.
Get advice
Codes and insurance rules vary; ask before fitting. See standard versus high-security deadbolts.
Questions to ask yourself
Is there glass within reach of the thumb turn? Who lives in the home: children, older adults, guests unfamiliar with the door? Where would a key be kept during the night? If an answer worries you, choose a single-cylinder deadbolt and secure the glass instead. If you do use a double-cylinder lock, keep a key in a fixed place near the door and make sure everyone in the house knows where it is.
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If you are locked out, need locks changed, or want to upgrade your security, call our dispatch line (8 AM to 10 PM) at 📞 437-295-4001 for a fast, reliable mobile response.