The short answer is that it fits far more often than people expect, including on staircases that look impossible. Here is what actually decides it.
Things that are not obstacles
A turn. Makes it a curved rail, which costs more and takes three to five weeks to manufacture, but it fits.
A narrow flight. The folded lift takes roughly eleven inches. Harmar publishes the Pinnacle SL600 at 10.5 inches folded for exactly this.
An intermediate landing. The rail runs continuously over it, so the user boards once and gets off once.
A door at the bottom. A hinged or folding rail section lifts the track clear when parked. It has to be ordered with the lift rather than added later.
Outdoor steps. Different equipment entirely, weather-rated throughout. Our outdoor page covers it.
Stone, brick or concrete steps. Masonry anchors rather than wood screws. Entirely workable.
Things that genuinely cause difficulty
Open risers with nothing solid to fix into. The rail brackets need something to hold. Frequently solvable with added structure, not always.
A very tight spiral. Where the inner radius is smaller than the rail can follow. This is the most common genuine no.
A doorway immediately at the top step. Where the only viable rail position runs through the door. Sometimes solved by parking on the other side, sometimes not.
Stairs that are not structurally sound. A lift puts load into the treads. If the staircase itself needs work, that comes first.
The person, not the staircase
The more common reason a stairlift is the wrong answer has nothing to do with the stairs.
If somebody travels seated in a wheelchair, a stairlift does not carry the chair and is the wrong machine. If somebody cannot transfer onto a seat safely, or their knees buckle during a stand-to-sit, Bruno names the Elite over the Elan for exactly that reason.
Say what the transfer looks like before anybody quotes. It decides more than the measurements do.
What we do when the answer is no
We say so, and then we look at what else solves it. A platform lift in a different part of the house. A ground-floor rearrangement, which is unglamorous and frequently the best answer. Occasionally a home elevator where the household intends to stay.
And sometimes the conclusion is that this house will not work, which is a hard thing to hear and better heard from us at a free survey than discovered after a deposit.
How to get a quick read
Send a photograph from the bottom looking up and one from the top looking down. Between them they show the turn, the width, the handrail and the construction, which is most of what anybody needs to tell you whether this is straightforward.
All consultations, estimates and scopes of work are free of charge, with no pressure or obligation. If the stairs turn out not to be the main difficulty, smaller equipment ships free from our online shop.
What a survey actually checks
Beyond the obvious measurements, a surveyor is looking at what the treads are built from and whether they will take the fixings, where the power is relative to the parking points, what is at the top and bottom that the lift must not block, which side suits the person’s transfer, and whether the staircase itself is sound.
That last one is worth stating. A lift puts load into the treads, so a staircase with movement in it gets addressed before anything is fitted.
Two straight lifts instead of one curved
Where a flight has a proper landing with room to stand and turn, two straight lifts can cost meaningfully less than one curved rail and go in far faster.
The catch is a transfer halfway up: a stand, a turn and a sit, performed on a landing, by somebody whose balance is the reason you are reading this. For somebody steady on their feet it is fine. For somebody who is not, it is a bad idea and we will say so rather than take the cheaper sale.
Getting an answer quickly
A photograph from each end will usually settle whether your staircase is straightforward, unusual or genuinely difficult. That costs nobody anything and saves a visit where the answer was going to be no.
Where it is difficult, there is nearly always another route: a different location, a ground-floor rearrangement, or equipment rather than machinery. Our stairlift page covers the models we fit.
Basements and split levels
Both are common and both are usually straightforward. A basement flight is often shorter and steeper than the main stairs, which is fine, and frequently has a door at the bottom, which means specifying a hinged rail section with the order.
Split levels with a short run to a half landing are among the cheapest jobs we do, and among the most useful, because that half flight is often the only thing standing between somebody and their own bedroom. Smaller equipment ships free from our online shop if the stairs turn out not to be it.