Written by the MB Elevator engineering team. The same engineers who survey, install and service the lifts we write about.
Shaft dimensions and pit depth are the two civil-work numbers that decide whether a given elevator system will even physically fit your building, before any conversation about cost or technology gets started at all. Get these wrong early and you'll end up redesigning your quote from scratch later.
Shaft size
Shaft dimensions scale with cabin capacity, so a compact 2-person home lift needs a considerably smaller footprint than a 6 to 8 person passenger cabin does. Beyond the cabin itself, the shaft also needs clearance for guide rails, counterweights on traction systems, and door mechanisms, which is exactly why the shaft always ends up noticeably larger than the cabin sitting inside it, sometimes by a surprising margin to someone seeing the numbers for the first time.
Pit depth
The pit is the recess below your lowest landing floor, needed for buffer systems and clearance when the cabin's at its lowest position. Deeper pits are standard for traditional traction systems. Many hydraulic and MRL systems, though, can be specified with a shallow pit, or in some retrofit cases, minimal to no pit at all, which is genuinely common in older buildings where excavating a deep pit just isn't structurally practical without major work.
Headroom
Clearance above your top landing floor is needed so the cabin can travel to its highest position safely, with buffer distance built in. This is often the constraint that gets missed in older buildings with lower ceiling heights near the roof, so it's worth checking early rather than discovering it late in the process when options are more limited.
Why these numbers deserve an actual site visit, not a guess
These three measurements interact with each other in ways that are hard to judge from a floor plan alone. A building might have a perfectly adequate shaft footprint but insufficient headroom, or enough pit depth but a structural beam running exactly where a counterweight needs clearance. This is exactly why we measure in person rather than working from drawings, since drawings don't always reflect what was actually built.
What this means if you're retrofitting
If your building can't accommodate a deep pit or a full-height shaft, that doesn't rule out an elevator altogether, it just rules out certain technologies. Our MRL and hydraulic pages cover systems designed around exactly this kind of constraint, and our installation team measures the actual numbers during a site survey rather than working off general rules of thumb that may not apply to your specific building.
Don't rely on old drawings alone
Even if you have original architectural drawings for your building, it's worth having actual measurements taken rather than trusting the drawings alone. Buildings get modified over the years in ways that don't always make it back onto the official plans, and a shaft that looks fine on paper sometimes has a beam or a duct running through it in reality.
What to do if none of the standard options fit
Occasionally a building genuinely doesn't have enough space for any standard configuration, no pit clearance, no headroom, and a tight footprint all at once. In these cases, it's worth having an honest conversation about what compromises are actually possible, whether that's a reduced capacity cabin, a slightly slower system, or in rare cases, minor structural modification. This is exactly the kind of edge case a site survey exists to work through properly rather than guess at remotely, and it's far better to hear about a real constraint honestly upfront than to have it surface midway through installation.
Need this looked at on site?
If this raised a question specific to your building, tell us about it and we’ll get back to you with a straight answer.