Elevator shafts are built first in high-rise construction because they double as the building’s structural spine. The concrete walls surrounding the shaft aren’t just there to house elevators. They form what engineers call a “shear wall core,” a rigid vertical column that holds the entire building steady against wind, earthquakes, and its own weight. Building this core first gives every other part of the structure something solid to connect to, and it keeps the overall construction schedule from falling months behind.
The Core Is the Building’s Backbone
A tall building faces two main challenges: supporting the weight of everything above (gravity loads) and resisting sideways forces from wind and seismic activity (lateral loads). The elevator shaft solves both problems at once. Its thick reinforced concrete walls act as vertical cantilevers anchored deep into the foundation, resisting the push of wind and the shaking of earthquakes by absorbing those forces and transferring them down into the ground.
This is why you’ll see a lonely concrete rectangle rising from a construction site long before any floors, walls, or windows appear. That rectangle is the elevator core, and it’s typically positioned near the center of the building’s footprint. Placing it centrally distributes its stabilizing effect evenly in all directions, reducing how much the building sways or twists under lateral pressure. Research on multi-story buildings confirms that when these cores are positioned strategically, they significantly reduce lateral displacement during earthquakes compared to buildings relying on the frame alone.
Without this core in place, the steel or concrete frame going up around it would be vulnerable to lateral forces during construction. The core gives the partially built structure something to brace against while the rest of the skeleton is assembled floor by floor.
Concrete Needs a Head Start
There’s a practical timing problem that makes early construction essential: concrete cures slowly. Steel framing, by contrast, goes up fast. According to the American Society of Civil Engineers, steel can be erected roughly twice as fast as a concrete core can be placed, because each pour of concrete needs time to harden and gain strength before the next section can be built on top of it.
In most modern high-rises, the building uses a hybrid system: a concrete core for the elevator shaft and a steel frame for the floors radiating outward. If crews tried to build both at the same pace, the steel team would finish weeks or months ahead of the concrete team, then sit idle waiting for the core to catch up. That idle time costs enormous amounts of money on a major project. So the standard approach is to start the concrete core well in advance, letting it climb upward at its slower pace. The steel erection crew begins later and works faster, ideally reaching the top of the building right around the same time the core does. Ron Klemencic, a prominent structural engineer, has described this lag as being “on the order of months,” making it one of the most important scheduling decisions in high-rise construction.
Vertical Transportation Drives the Schedule
Once the core is up, it immediately becomes the construction site’s main highway. Tower cranes handle heavy lifts from the outside, but the elevator shafts (often fitted with temporary construction hoists) move workers, tools, and lighter materials up and down the building. On a 40- or 50-story project, getting people and supplies to the right floor at the right time is a serious logistical challenge.
Research published in Scientific Reports found that vertical transportation is the single biggest bottleneck in high-rise construction supply chains. When elevator or hoist scheduling is inefficient, it can cause a 20 to 30 percent delay in overall project completion. In one modeled scenario, ignoring delivery timing led to a cumulative delay of over 1,600 minutes across material deliveries, enough to seriously disrupt on-site work. Having the shaft built early means these hoists can be operational sooner, keeping materials flowing to upper floors as the building rises.
How the Sequence Actually Works
On a typical high-rise project, the construction sequence looks something like this. Foundation work comes first, including deep piles or caissons driven into stable ground. The elevator core begins rising almost immediately after the foundation is ready, using a technique called slip-forming or jump-forming, where specialized formwork climbs the core as each section of concrete is poured and cured. This process can add a new section every few days.
Once the core has a sufficient lead, steel erectors begin assembling the floor framing outward from the core. Each floor’s steel beams connect back to the core, using it as an anchor point. Metal decking is laid over the steel beams, concrete is poured for the floor slabs, and the process repeats upward. Meanwhile, the core team stays several floors ahead, maintaining the gap. On some projects, the core might be 15 to 20 floors above the steel erection at any given time.
This staggered approach means multiple crews work simultaneously on different parts of the building. Foundation crews might still be finishing basement levels while the core is already dozens of stories high and steel is being erected in between. It’s an overlapping assembly line moving vertically.
Why Not Build Everything at the Same Time?
Some builders have experimented with composite cores that use steel framing instead of (or alongside) poured concrete, specifically to eliminate the head-start problem. A steel-framed core can go up at the same speed as the rest of the building, removing months from the schedule. The ASCE has highlighted projects using steel-and-concrete composite cores as a way to fast-track construction.
But fully steel cores sacrifice some of the benefits that make concrete cores so effective. Concrete is heavier, which helps resist overturning forces. It’s also better at damping vibrations, reducing the sway that occupants feel on windy days. And thick concrete walls around elevator shafts provide built-in fire resistance, since concrete doesn’t lose structural integrity as quickly as steel in extreme heat. For most high-rises, the tradeoff favors starting with a traditional concrete core and accepting the scheduling lag.
The elevator shaft, in other words, isn’t just a hole in the building where the elevators happen to go. It’s the structural, logistical, and scheduling foundation that everything else is built around.