Stairs are graph connectors.
Who This Matters To (And Why)
Critical: Architect,GC,City. These parties make or lose money directly based on this thesis.
Important: Engineer,Developer,Inspector. These parties execute decisions shaped by this thesis.
Context: Banker,Interior Design,Investor. These parties need to understand it to avoid friction.
Highest typology impact: Multifamily,Office,Hotel,Mixed Use. Lower impact: Retail,Industrial.
A stair is a vertical edge in the building graph. It connects floor nodes and sets egress capacity.
How It Shapes Development
Stairs are graph connectors because they create edges between floor-level nodes in the building's vertical circulation graph. Every stair connects two floor plates. The properties of that connection — width, fire rating, pressurization, travel distance served — are properties of the edge, not the stair itself. A stair serving a single-tenant office floor has different edge properties than a stair serving a high-rise residential egress core, because the nodes it connects have different occupancy loads and code requirements.
Stair count drives building cost and efficiency in ways that are not always visible at the schematic design level. A code-compliant building requires at minimum two remote egress stairs above a certain floor area threshold. Each stair occupies roughly 200–250 SF of floor plate per floor. On a 20-story building, two stairs consume 8,000–10,000 SF of gross area that produces no revenue. Adding a third stair to improve egress performance or reduce travel distance costs another 4,000–5,000 SF of rentable area across the building height. The decision to add a stair is a financial decision expressed in floor plate geometry.
Remoteness requirements for egress stairs are a graph property. Building codes require that exits be “remote” from each other — typically separated by at least one-third to one-half the diagonal of the floor plate. This is a constraint on graph topology: the two exit nodes must be far enough apart that a single fire event cannot simultaneously block both paths. The floor plan is valid only if the graph has at least two paths from every occupied room to an exit, with those paths being sufficiently divergent.
Scissor stairs are a structural optimization of the graph connector problem. Two egress stairs occupy the same structural bay by interleaving their runs. From the outside they look like one core. From the graph perspective they are two independent edges sharing a common bounding box. The fire separation between the scissor stair flights is the proof that the graph has two distinct paths even though the physical envelope is shared. The graph logic drives the fire rating requirement, not the other way around.