Staircase installation: what a good fit actually looks like
Written by Scott Jones, The Stair Guys, independent staircase measuring and sourcing specialists·Last updated
There is a truth about fitting a staircase that catches people out: most of whether it goes in well is decided before it ever reaches your house. A stair that was properly measured, dry-fitted and cut to length in the workshop mostly fits itself. A stair that was not becomes a fight on site, and no amount of skill on the day fully undoes a bad start. So a good installation is really two things at once: a stair that was made right, and a fitter who knows how to fix it in properly.
It starts at the factory
The single biggest factor in a clean fit is whether the stair was dry-fitted, assembled once in the workshop to prove it goes together, before it shipped. Add a proper site measure that allowed for the finished floors and the real, out-of-square walls, and handrails cut to length rather than left to the fitter, and the job on site is mostly assembly. Skip those and a small factory error, a machine setting that slipped, is not found until the fitter is stood in your hall trying to make good a mistake that should never have left the workshop. This is why we say quality is built in at the factory. For what to check before you order, see what you are actually getting.
Fixing it in: the bits that matter
- The strings fix into something solid. The strings, the boards that carry the steps, have to be screwed into a joist, a trimmer, or timber noggings set between the studs of a plasterboard wall, never into the plasterboard alone. On a stud wall that means putting noggings in first, on the line of the fixings, so there is timber to screw to. A stair fixed to board works loose.
- The wedges are glued. Under the treads and risers, wedges lock each step tight into the strings. They are glued, not just tapped in dry, so the joint is rigid and stays silent. A stair wedged dry is a stair that will creak.
- Glue is kept off the show timber. Where the stair will be seen, on a stained or uncarpeted flight, glue squeezed out of a joint is a mess that is hard to remove, so a good fitter keeps the bead back from the show face.
- Handrails cut to length and tenoned. On a quality stair the handrails arrive cut to length and tenoned into the newels, not left for the fitter to butt up and screw on the day.
What a good and a bad install look like
A good installation is quiet and tight. The treads do not creak, the balustrade does not move, the strings sit scribed neatly to the wall with no daylight behind them, and nothing has been packed out with slivers of timber to hide a stair that did not fit. A bad one announces itself: creaks within weeks, gaps at the wall, packing under the newels, a handrail that flexes. Most of that traces back not to the fitter's hour on site but to whether the stair was made and measured right in the first place, which is the whole argument for a measured, dry-fitted, made-to-order stair over one ordered blind off a form. See also why an online stair designer can get it wrong.
Frequently asked
What makes a good staircase installation?+
Mostly a stair that was made right: professionally measured on site allowing for finished floors and out-of-square walls, dry-fitted in the workshop, and handrails cut to length. On site, the strings are fixed into something solid, the wedges are glued so nothing creaks, and glue is kept off any show timber. A good fit is quiet, tight and scribed neatly to the wall.
Why do staircases creak, and can it be avoided?+
The most common cause is wedges that were tapped in dry rather than glued, so the joints between the treads, risers and strings are not rigid and move under foot. Gluing the wedges to form a rigid joint, and fixing the strings into solid timber rather than plasterboard, is what keeps a stair silent.
Can a staircase be fixed to a plasterboard wall?+
Not to the plasterboard alone. The string has to be screwed into something solid behind it, a joist, a trimmer, or timber noggings fitted between the studs on the line of the fixings. Fixed to board alone, the stair works loose. On a stud wall the noggings go in before the stair.
Is the fitting or the factory more important for a good staircase?+
The factory, more than people expect. A stair that was properly measured, dry-fitted and cut to length mostly fits itself, while one that was not becomes a fight on site that skill alone cannot fully fix. Good fitting matters, but it works with a well-made stair, not instead of one.
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