You do not need to measure your own staircase. A survey is free and the installer will do it properly. But taking five measurements first is worth doing, because it tells you whether a quote you have been given is plausible and it speeds up the conversation.
What to measure
1. Total length of the flight. Run a tape from the front edge of the top step down to the floor at the bottom, following the slope. This is the number that drives rail length on a straight lift.
2. Width at the narrowest point. Wall to wall, or wall to the inside of the banister. Measure partway up rather than at the bottom, because the narrowest point is rarely at either end.
3. Number of steps. Count the treads, not the risers, and note whether any of them are wedge-shaped.
4. Clearance at the top. From the top step to the nearest wall or doorway. This decides where the lift can park without blocking anything.
5. Clearance at the bottom. Same thing. Note if a door opens across the foot of the stairs, because that needs a hinged rail section specified with the order rather than added later.
The two photographs
One from the bottom looking up, one from the top looking down. Between them they show the turn, the handrail, the doorways and the general construction, which is most of what a supplier needs to tell you whether you are looking at a straight or a curved rail.
Send those with your first enquiry and you will get a far more useful first answer.
The thing people get wrong
Wedge-shaped steps. A single winder at the top makes the whole job a curved one, because the rail has to follow the turn. People measure a flight, describe it as straight, and then discover otherwise at survey.
Look specifically for any step that is wider at one end than the other. If there is one, you have a curved staircase regardless of how straight the rest looks. Our curved stairlift page explains what that means for time and cost.
What the numbers tell you
Width under about 30 inches at the narrowest point is worth flagging early, though it is rarely fatal. Harmar publishes the Pinnacle SL600 as folding to 10.5 inches for exactly this situation, and Bruno designs the Elan with a narrow vertical rail for the same reason.
A very long flight may need extra rail sections, which is a cost line rather than a problem. A very short one to a split level is usually the cheapest job we do.
What you cannot measure yourself
Whether the treads will take the fixings, where the power is, and on a curved flight the exact geometry of each turn. Curved rails are measured with a calibrated camera kit or a full survey rather than a tape, because a quarter inch of error compounds over a turn and the rail is cut once.
So take the five measurements to inform the conversation, not to replace the survey.
Why a supplier should still visit
Anybody willing to quote a firm price from a phone call has either padded the number to cover what they have not seen, or will revise it once they arrive. Neither is what you want.
All consultations, estimates and scopes of work are free of charge, with no pressure or obligation. Our stairlift page covers the models, and smaller equipment ships free from our online shop if the stairs turn out not to be the problem.
What to note as well as measure
- Where the power outlets are at the top and bottom. These lifts charge at parking points from an ordinary outlet.
- Which side the handrail is on. It usually stays, and it affects which side the rail goes.
- What the treads are made of. Timber, stone, concrete and open-backed stairs all fix differently.
- Whether the carpet is being replaced soon. Do the flooring first. The rail fixes to the treads.
- What is at the top and bottom. A doorway, a radiator, a newel post.
Which side should it go on
Not usually your decision to make from a tape measure, and worth thinking about before the survey so you can discuss it properly.
The answer should follow the person’s transfer rather than the installer’s convenience. Somebody with a weaker left side gets on and off a particular way, and that ought to drive the choice. Where the doors are at each end matters second.
What to do with the numbers
Send them with the photographs when you first make contact. You will get a more useful answer, and when a surveyor arrives the conversation starts from a real understanding rather than from scratch.
It also gives you a check on any quote. If somebody quotes a straight rail for a flight you have measured as turning, you have learned something before paying a deposit.