Stannah's current guide gives typical stair widths of about 27 inches for a straight lift and around 30 inches for a curved model, but stair layout and lift choice change the fit. Turns and landings may require a custom curved rail; survey clearances, transfers, parking and power before ordering.
Start with the stair shape. A straight flight can use a straight rail; turns and intermediate landings can require a custom curved rail. The room around the stairs and the rider’s transfer routine decide whether the proposed installation works in daily use.
Compare the rail paths
| Stair layout and likely rail | What the survey should map |
|---|---|
| One straight flight, with a straight rail cut to the run | Rail length, top and bottom extensions, landing clearance and seat parking. |
| A turn or intermediate landing, which may need a custom curved rail | Turn geometry, landing positions, rail path and space kept open for others. |
| Outdoor steps, with an outdoor-rated lift if the maker offers one | Weather exposure, mounting surface, drainage, cover and service access. |
These are planning categories, not a fit guarantee. Stannah describes straight rails for straight runs and custom-made curved rails for turns and multi-flight stairs. Its stairlift dimensions guide says straight installations generally need about 27 inches and curved installations around 30 inches, depending on the staircase. Review its stairlift types and rail options and compare the proposed design with the exact stair survey.
Check the whole route and transfer
Measure the stair width at several points, including handrails, trim and tight turns. Check whether a rail or folded seat will block a doorway, hall or required walking path. Look at the entry and exit landing, the space to sit and stand, and where the chair parks when it is not in use. Confirm the rider can operate the controls and transfer as planned; involve an occupational therapist or mobility specialist when that would help.
Ask the installer about the seat and footrest folding depth, swivel and lock, track position, power supply, battery behavior during outages, weight limit, service area, warranty and cleaning. Have the installer document clearances and any conflict with doors, another stair user or a second lift.
If stairs are not the only barrier, compare threshold ramps and doorway clearances or review ramp slope and landing requirements. See the Medicare mobility-equipment guide before budgeting for coverage. Browse home access.
Common questions
When do I need a curved stair lift?
A staircase with a turn, intermediate landing or changing angle may need a curved rail. The installer must survey the actual stair geometry and the selected model.
Can a stair lift fit a narrow staircase?
It depends on the lift, rail position, stair dimensions and clearance for people using the stairs. Measure at several points and request an in-home survey before ordering.
Does a curved rail fit any staircase?
No. A curved rail is made for the measured route and chosen lift. Confirm turns, landings, rail parking and any obstructions with the installer.
Will Medicare pay for a stair lift?
Medicare generally treats stair lifts as home modifications rather than covered durable medical equipment. Review the coverage discussion in our [mobility equipment guide](/guides/medicare-coverage-for-mobility-equipment) and confirm any benefit with the plan.