This post will be published in Door Security + Safety
According to Merriam-Webster, a deadbolt is defined as: “a lock bolt that is moved by turning a knob or key without action of a spring.” While most deadbolts (AKA deadlocks) are actually operated by a thumbturn rather than a knob, the important point is that the deadbolt is not spring-loaded and does not latch automatically. The bolt must be thrown or retracted manually, and stays in that position until another manual operation is performed. There is often confusion surrounding the use of deadbolts on doors serving a means of egress. There are many considerations – from the life safety and egress requirements, to fire doors and doors on accessible routes. Hopefully, this article will clarify the requirements and address some of the misconceptions.
Deadbolts are not “bolt locks.”
Yes, really, and this is where interpretations often go awry. The International Building Code (IBC) includes a section called “Bolt Locks,” and states that “Manually operated flush bolts or surface bolts are not permitted,” with some exceptions. If someone is not familiar with hardware terminology, it’s easy to interpret this prohibition as applicable to deadbolts. But the IBC Commentary includes further information and diagrams which clarify that this section applies to the flush bolts and surface bolts installed on the inactive leaf of a pair of doors, which project into the frame head and into the floor or threshold. Flush bolts and surface bolts that are operated manually are prohibited on some egress doors because it may be difficult for building occupants to quickly identify and operate these bolts in an emergency. In addition to the locations where the model codes allow the use of manual flush bolts and surface bolts, automatic flush bolts are another option for the inactive leaf, as well as panic hardware. The IBC section called “Bolt Locks” does not address deadbolts.
Doors in a means of egress must unlatch with one releasing motion.
This is true – usually. Even doors serving small rooms such as single-occupancy restrooms and dressing rooms are required to unlatch with one releasing motion. NFPA 101 – The Life Safety Code does include an exception that allows two releasing operations for existing hardware on a door leaf serving an area with an occupant load of 3 people or less, as long as the two operations do not have to be performed simultaneously. BUT, this exception only applies to existing hardware (not new hardware on existing doors) on small rooms in buildings where NFPA 101 is the applicable code; the IBC does not include a similar exception.
There are exceptions in both the IBC and NFPA 101 that allow doors serving most multi-family residential dwelling units and sleeping units to have a deadbolt or other security device in addition to the latching hardware. These devices must be operable from the inside without the use of a key or tool, and must require only one additional releasing operation (refer to NFPA 101 for exceptions addressing existing security devices). The IBC limits this second security device to dwelling units with an occupant load of 10 or less – typically units with an area of 2,000 square feet, maximum.
Note that these dwelling and sleeping units must be Group R or Residential occupancies. Some types of units may fall under Group I (Institutional) or Health Care, and this exception does not apply to those occupancy types. In addition, there are some state and local code requirements which mandate that locks on dwelling units and sleeping units must unlatch with one operation. In these jurisdictions, a separate deadbolt would not be allowed.
Deadbolts that are integral to a mortise lock or interconnected lock would be acceptable if both the latchbolt and deadbolt retract when the lever is turned. This type of lock would also be allowed for egress doors in other occupancy types. If panic hardware is required, a separate deadbolt should never be installed in addition to the panic hardware.
Deadbolts on fire doors must be labeled.
Many entrance doors to dwelling units and sleeping units are fire door assemblies. When deadbolts are installed on fire doors they must be labeled, which means that they have been successfully tested to UL 10C / NFPA 252 – the standards used to test and certify fire door assemblies and components. Components installed as part of a fire door assembly are required by NFPA 80 – Standard for Fire Doors and Other Opening Protectives, to be listed/labeled, so it is not permissible to install a deadbolt on a fire door if the deadbolt has not been labeled for this purpose. NFPA 80 also limits the job-site preparations and field modifications that may be performed on a fire door assembly. These limitations should be clearly understood before conducting any retrofit work on a fire door assembly.
Because the US codes and standards require fire door assemblies to have hardware with an active latchbolt, a labeled latchset or lockset would be required in addition to the labeled deadbolt. The deadbolt alone would not provide the positive latching function needed to keep the door in the closed and latched position if a fire occurred. It’s important to consider the requirements related to both fire and egress, as well as accessibility.
Double-cylinder deadbolts are acceptable in some locations.
Using a deadbolt that requires a key to unlock it from the inside seems like it would negatively impact egress, but in certain applications it is allowed by code. The locations where these locks are allowed by the IBC include: assembly occupancies with an occupant load of 300 people or less, business, factory, mercantile, and storage occupancies, and places of religious worship. In these buildings, the main door or doors may be equipped with locking devices that are operated by a key on the egress side (as well as a key on the exterior). The locking device must be readily distinguishable as locked, and there must be signage on or adjacent to the door on the egress side, stating “THIS DOOR TO REMAIN UNLOCKED WHEN THIS SPACE IS OCCUPIED.” The letters on the sign must be at least 1 inch high on a contrasting background. The use of the key-operated lock may be revoked by the code official for due cause.
The section of the model codes that applies to key-operated locks (double-cylinder deadbolts) would not allow the use of a single-cylinder deadbolt with a thumbturn. With that said, there are locations where a thumbturn deadbolt would be allowed:
- The application would have to be one where panic hardware is not required.
- The door would not be able to be fire-rated (unless it’s the entrance door to a dwelling unit or sleeping unit, or other location where two releasing operations are allowed).
- The deadbolt would have to be the only locking/latching device on the door (unless it’s the entrance door to a dwelling unit or sleeping unit, or other location where two releasing operations are allowed).
- The thumbturn and cylinder would have to be between 34 inches and 48 inches above the floor.
- The thumbturn would have to be operable without tight grasping, pinching, or twisting of the wrist.
Note: In the 2021 IBC, another section was added that would allow double-cylinder deadbolts on egress doors serving exterior specifies, if certain criteria were met. There is more information in this Decoded article.
Single-family and 2-family homes have different requirements for deadbolts.
The International Residential Code (IRC) has been adopted in most US states for the construction of 1- and 2-family homes; the IRC requires dwellings to have a code-compliant means of egress which opens directly into a public way or to a yard or court that opens to a public way. A dwelling unit must have at least one egress door that is side-hinged, and has a clear width of at least 32 inches and a clear height of not less than 78 inches. Egress doors must be readily openable from inside of the dwelling without the use of a key or special knowledge or effort. While a deadbolt with a thumbturn is typically acceptable on these doors, a double-cylinder deadbolt does not meet the IRC’s requirements for a lock on an egress door.
Classroom function deadbolts are commonly used on multi-stall restrooms.
In Chapter 29 – Plumbing Systems, the IBC includes a paragraph which states: “Where a toilet room is provided for the use of multiple occupants, the egress door for the room shall not be lockable from the inside of the room. This section does not apply to family or assisted-use toilet rooms.” According to the IBC Commentary, the purpose of this requirement is to prevent multiple-occupant toilet rooms from becoming safe havens for illicit activities.
In many facilities, doors serving multi-stall restrooms are equipped with classroom function deadbolts so the doors can be locked in case of a plumbing problem or for whatever reason access to the room needs to be limited. The function that is typically specified is a classroom function deadbolt, but there is sometimes confusion about how these locks are intended to operate.
A classroom function deadbolt can be locked and unlocked from the outside with a key. When locked (bolt projected), the inside thumbturn can be used to retract the bolt, in case someone is inadvertently locked inside. The inside thumbturn will not project the bolt (it will only retract it), so this type of lock meets the IBC’s prohibition on lockable doors serving multi-stall restrooms.
Note that the emergency plans for some schools and other buildings include the use of restrooms as lockdown areas where building occupants can go if they need to find a safe haven. To avoid uncontrolled lockdown of these rooms, one option could be a deadbolt function that would allow a teacher with a key to lock the door from the inside, but would also incorporate a thumbturn to allow free egress.
In most cases, deadbolts are required to meet the accessibility standards.
Door hardware must be operable with no tight grasping, pinching, or twisting of the wrist. That means that the thumbturn must be long enough to be operated with the side of someone’s palm, or the tip of a pencil, and within the operable force limitations of the applicable standard. Operable parts – including thumbturns, keypads, and access control readers – must be mounted between 34 inches and 48 inches above the floor or ground, or as required by state or local codes. Note that the allowable mounting height in California is more restrictive – 34 inches to 44 inches above the floor or ground. While there may be exceptions for existing deadbolts mounted in the bottom rail of a glass door, protruding hardware in that location can create a conflict with the requirement for a flush and smooth area in the bottom 10 inches on the push side of manually-operated doors.
One question that has come up recently is whether a deadbolt impacts the maneuvering clearance for a door opening. For a front approach on the push side of the opening, the accessibility standards require additional maneuvering clearance on the latch side if the door has both a door closer and a latch. The standards do not clarify whether the additional clearance would be required if the door has a door closer and a deadbolt instead of a latch. When I discussed this with International Code Council (ICC) staff, we agreed that because the deadbolt is held retracted and is not self-latching, the additional maneuvering clearance should not be required if the door is equipped with a door closer and deadbolt, with no positive-latching hardware.
Here’s the bottom line on deadbolts.
- Doors in a means of egress are required to unlatch with one operation – with a few exceptions.
- In most jurisdictions, residential dwelling units and sleeping units are allowed to have a deadbolt in addition to the latching hardware.
- If installed on a fire door, the deadbolt has to be labeled for that purpose, and alterations to existing fire doors must be made in accordance with NFPA 80 and the manufacturer’s listings.
- Double-cylinder deadbolts are allowed under certain circumstances if the required criteria are met.
- Thumbturns and other operable hardware must operate with no tight grasping, pinching, or twisting of the wrist.
- Releasing devices must be mounted between 34 inches and 48 inches above the floor, or as required by state/local codes.
- Refer to the applicable codes and standards for additional information.