The permissible dimensional deviation of a hoistway from the nominal design geometry specified by the elevator manufacturer.
Full Definition
Elevator shaft tolerance defines the allowable deviation of as-built hoistway dimensions from the nominal values specified in the elevator manufacturer's layout drawing, measured after civil construction is complete but before elevator installation begins. Tolerances govern the straightness, plumb, cross-section, and surface finish of the hoistway that ensures safe operation and achieves the required clearances between moving parts and fixed structures. Typical tolerance requirements published by major manufacturers include: internal cross-section ± 20 mm per side from nominal; plumb over the full hoistway height ≤ ± 25 mm (some manufacturers restrict this to ± 10 mm for MRL and high-speed installations); pit depth +50 / −0 mm; overhead clearance +50 / −0 mm; sill-to-sill landing accuracy ± 5 mm for level stopping performance. When the shaft survey reveals a deviation exceeding the manufacturer's tolerance, the civil contractor must remedy the deficiency — typically by grinding concrete protrusions, adding plaster, or repositioning the sill blockout — before the elevator order is placed. Excessive shaft out-of-plumb that cannot be corrected must be accommodated by the elevator engineer with modified guide rail bracket spacing and extended rail joints, potentially increasing installation cost. EN 81-20 does not prescribe shaft tolerances directly; they are manufacturer-specific and contractually binding between the civil contractor and the elevator contractor.
