Timber Egress Stairs
CLT egress stairs at International House Sydney
Photo: Ben Guthrie
Egress stairs in commercial buildings provide a safe and secure path of exit during emergencies - but why can’t they also provide amenity and delight for the users ?
The Building Code of Australia (BCA) requires a certain number of exit points in any building, to provide occupants with an egress path in times of fire or disaster. The BCA dictates quantity, separation, width, handrail design, step dimensions etc for egress stairs - but does not attempt to inform the user experience of being within the stair well, which typically results in a dull, dim and soulless exposed concrete space, only suitable for use in times of peril.
As these building safety features consume floor area in the building, why shouldn’t they also provide additional amenity to the users, such as: attractive and inviting inter-tenancy stairs connecting floors in preference to using lifts (reducing energy use and facilitating exercise); enhancing natural light and views from the floor plates and stairs by providing glass to part of the stair enclosure, both internal and external.
Photo: Ben Guthrie
At both International House and Daramu House the egress stairs are fully fabricated from CLT and Glulam components. Treads and risers have been finished with recycled hardwood timber boards to provide additional robustness to the trafficable surfaces. Handrails and balustrades are detailed with a minimal, refined approach to quietly compliment the solid timber elements, rather than compete.
Exploded axonometric view of typical pre-fabricated stair components
In terms of construction, the stair well is one of the most labour intensive parts in the assembly process, incorporating the flights and landings, treads and risers, non-slip nosings, handrails, as well as the surrounding fire rated and sealed enclosure. Arbor.tect have been developing a process and procedure for the pre-assembly of a completely finished egress stair volume, to be transported and installed with one site crane lift per level, delivering considerable time savings by further utilising off-site and modular construction efficiencies.
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