Building an elevator in a home requires a significant amount of space and proper permitting. Applying for permits can add to the cost significantly, especially if the plans require adding more space to the home.
Elevators work by using a counterweight to keep the elevator in place, and this counterweight requires its own compartment. This counterweight connects to the elevator through heavy-duty steel cabling, and it's raised and lowered when the elevator moves. All of this equipment takes up a significant amount of space, so it's easy to underestimate how much space the elevator requires. In many cases, installing an elevator means adding an addition to the home, which is generally expensive and requires permitting.
Because elevators are potentially dangerous, governments almost always require that experts install them. These various requirements generally mean that homeowners need to hire a general contractor with experience in commercial spaces, where elevators are far more common. General contractors can provide estimates for how much the installation and permitting costs.
Elevators typically come in custom kits ready for installation, so subcontractors should be able to start working after the plans have been formalized and the parts have arrived. Depending on local laws, the elevator might need to be inspected by an expert, although elevators installed in residential units might not have the same strict inspection requirements of commercial elevators.