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Requirements for fire stair re-entry under the Deemed-to-Satisfy (DTS) Provisions of the National Constriction Code (NCC) are contained in Clause D2.22 (Re-entry from fire-isolated exits). The re-entry provisions covered by this clause apply only to fire-isolated exits serving Class 9a (healthcare) buildings, Class 9c buildings, and fire-isolated stairways serving stories above an effective height of 25m (i.e. high-rise buildings). Where the fire-isolated stairway serves floors above an effective height of 25m, the requirements apply to all doors within the stairway, including doors serving floors below 25m effective height.
D2.22 is a relatively short clause, but is the subject of a significant among of misunderstanding and misapplication within the building industry. This article summarises our understanding of how this clause is intended to be applied, and what potential fire engineered Performance Solutions may be available in respect to fire stair re-entry. As with all interpretation of the NCC, the requirements can vary from building to building, and therefore it is important that you always seek project specific advice from an appropriately registered and experienced Building Certifier or Surveyor.
According to the Guide to the BCA, the intent of Clause D2.22 is to minimise the risk that a person becomes trapped in a fire-isolated exit. Clause D2.22 provides two options achieve this outcome. The first option, contained in Clause D2.22(a), is straightforward. It simply requires that doors of a fire-isolated exit must not be locked from the inside. However while this option clearly minimises the risk of becoming trapped in a stair, it does not address another important consideration for building owners and occupiers, being stairwell security. It is often not desirable, if not actually unsafe, to allow free access from stairwells onto a floor plate. At the very least free handle access onto all floor plates from a stairwell can increase the risk of theft, and in some buildings (e.g. hospitals), may provide access to sensitive areas such as neo-natal care, operating theatres and pharmacies.
The DTS Provisions therefore provide alternatives to the requirement for all doors in a fire-isolated stairway to not be locked. These alternatives are contained in Clause D2.22(b), and it is interpretation of D2.22(b) that often causes problems.
The key to applying Clause D2.2(b) is to consider two separate conditions:
1. Normal Mode operation (i.e. non-fire mode)
2. Fire Mode operation
In normal mode operation, the objective of Clause D2.22(b) is to prevent occupants who have inadvertently entered a fire-isolated stairway from becoming trapped in the stairway, or from having to descend all the way to ground level in order to exit. For occupants of high-rise buildings, or vulnerable occupants in Class 9a and 9c buildings, descending to ground level may be very challenging and potentially hazardous. Clause D2.2(b) therefore provides two options to address this issue.
The first option, D2.22(b)(i), requires that free handle egress from the stairway be available on at least every fourth level (i.e. the doors on these levels are not able to be locked). This requirement means that in normal mode, no matter which level an occupant enters the stairway at, they are no more than two flights (up or down) from a door that will allow them to exit the stair. If ascending a stair is too onerous, the occupant has to descend no more than three flights to reach a door from which they can exit the stair. The stairs that are not locked must have a sign affixed to the door stating that re-entry is available.
Providing free handle re-entry on every forth level in normal mode operation may address security concerns in many instances (e.g. in a hospital this strategy may allow doors on key levels such as neo-natal care or pharmacy levels to remain locked). However in many cases this strategy will not resolve all security issues, for example in open floor plan office buildings or residential apartment buildings.
The DTS Provisions therefore provide a second option under Clause D2.22(b)(ii). Clause D2.22(b)(ii) permits all doors within the fire-isolated exit to remain locked during normal mode operation, providing an intercommunication system, or an audible or visual alarm system, operated from within the stairway is provided near the door. Although the DTS Provisions do not explicitly state as much, most Building Certifiers and Surveyors interpret Clause D2.22(b)(ii) to require an intercom at each level within the fire stair. A sign must also be fixed adjacent to such doors explaining the purpose and method of operation of the system.
The two options provided by the DTS Provisions under Clause D2.22(b) resolve most access security concerns, while still minimising the risk of an occupant becoming trapped in a stair. However what many building owners and operators do not appreciate is that these concessions only apply in normal mode operation (i.e. in non-fire mode). When the building’s fire alarm activates, Clause D2.22 requires that all fire-isolated exit doors must unlock. This means that any doors that are proposed to remain locked in normal mode operation under Clause D2.22(b), must be provided with an electronic access control system (EACS), so that the doors will release automatically in fire mode (i.e. on activation of the fire alarm system). Building owners, developers and builders must therefore be cognisant of the costs associated with the provision of an EACS to fire-isolated stairway doors if the intention is to permit some or all of the doors to remain locked during normal (non-fire) mode.
At Solis Fire Engineers, we can develop a Performance Solution to significantly reduce the number of intercom units required under Clause D2.22(b)(ii). This not only results in cost savings for the units themselves and the cabling runs (which can be substantial for tall buildings and/or multiple stairways), but also for ongoing testing and maintenance requirements over the lifecycle of the building.
Generally speaking, there is limited opportunity for fire engineered solutions to permit stairway entry doors to reman locked from the stair side in fire mode, however in certain circumstances it may be possible to allow key floors to remain locked, particularly in highly sensitive buildings such as hospitals, so please talk to us about your requirements if you feel this might apply to your project.
Finally, residential buildings with a single apartment per floor present a unique challenge in regard to stair re-entry provisions, when the fire-isolated stairway opens directly into the apartment. This arrangement can present a significant security risk for apartment occupants in fire mode if the stair doors unlock automatically. However there are ways in which the competing security and fire requirements can be balanced, but this may require some modification to the design, so it is vital that you talk to us early if you are contemplating a single apartment per floor arrangement.