Why an online stair designer can get it wrong
Written by Scott Jones, The Stair Guys, independent staircase measuring and sourcing specialists·Last updated
An online stair designer is a brilliant thing for a rough idea and a rough price. The trouble starts when people treat the number it spits out as a stair that will actually fit and pass. A configurator can only work from what you type in, and it quietly assumes a perfect world. Your house is not a perfect world.
Here is what an online designer assumes, and what a professional measure actually checks.
What an online designer assumes, and what a measure checks
- That your walls are square, plumb and straight. They are not. Real walls lean and bow, and a stair has to be scribed to fit them. Build to the exact wall-to-wall figure and it either will not go in or leaves gaps.
- That you allowed for the plaster. Measure to bare blockwork and forget the plaster, or the dot-and-dab going on top, and the finished opening is narrower than the number you typed.
- That you allowed for your floor finishes. The rise is set out finished-floor to finished-floor. Forget the tile, screed or carpet and every step is the wrong height and the risers are no longer equal.
- That your floors are level. A floor that falls across the opening throws the rise out at one end.
- That your headroom is fine. It cannot see the pinch point where you rise past the floor above or up into the roof. And in a loft, headroom is not only above your head as you climb, it is beneath you too, over the flight or landing below. Headroom is a three-dimensional problem, and a form is not.
- That the doors clear the stair. A door needs a clear zone at the bottom of the flight so it is not swinging into the first step.
- That every newel post runs down to the floor. The tool assumes each post carries down to the floor and the structure below it. If yours has to be cut or floated to work, the tool will never ask, so that is on you to flag, and a post that has not been designed for it is a weak point.
- That there is something solid to fix to. A string and a newel need to fix into solid wall, a joist or a trimmer, not plasterboard, and in a loft that support matters even more. The tool does not know what is behind your wall.
- That you can get it into the house. It has no idea whether the finished stair will make it through your front door and round to the opening.
- That a loft flight will not clash with the one below it. Stack a narrower loft flight over a wider main flight, say a 700mm flight above a 900mm one, and a newel or the structure can end up fouling the flight beneath. A configurator sizes each flight on its own and never checks the two as a stack.
None of this makes online designers bad. They are the right tool for a first look, and the wrong tool for the final order, because the one thing they cannot do is measure your actual, imperfect, real-world opening. That is why we measure every job on site. It is not us being awkward. It is the difference between a stair that fits and passes, and one that does neither.
Frequently asked
Are online stair designers accurate?+
They are accurate enough for a rough idea and a rough price, but only as accurate as what you type in. They assume square walls, allowed-for plaster and floor finishes, fine headroom, and that you know the regs. They cannot see your real, imperfect opening, so they should not be trusted for the final order.
Do I still need a professional measure if I have used an online stair designer?+
Yes. An online designer cannot check that your walls are straight, that headroom clears the pinch point, that there is something solid to fix to, or that the finished stair will even get into the house. A site survey checks all of that, which is why the final order should come off a measure, not a form.
Can an online stair configurator check building regulations?+
Up to a point. A good one enforces the basic geometry it was built around, so it will not usually let you set a pitch that is too steep or gaps that fail the 100mm sphere rule. But it cannot tell whether the ruleset matches your job, for example a Scottish job where the figures differ or a general-access building that needs a different stair category, and it cannot check the parts of compliance that depend on your real space. Passing the tool is not the same as passing Building Control.
Will a staircase built from an online design fit my house?+
Not reliably. The tool works from the figures you type in and assumes a perfect space. Out-of-square walls, plaster thickness, floor finishes, headroom and newel overhang routinely mean a stair designed online does not fit or get into the property. A site measure catches those before anything is built.
Related guides
- Why a staircase that works on the plan can still fail in realityA flat plan cannot show headroom, buildability or the real millimetres. Here are the staircase mishaps a drawing hides, from headroom and door swings to winders, the wrong stair category and newel posts, and why a site survey catches them.
- How a staircase is measured: total rise, going and step countA staircase is set out from the total rise, the finished-floor to finished-floor height, divided into an equal number of risers, then the going is set so the pitch and 2R plus G stay in range. Getting the finished floor levels right is the part that catches people out.
- How much space does a staircase need?A straight staircase for a normal storey needs roughly 2.6 to 3 metres of clear floor length for the flight, plus landing space at the top and bottom and the stairwell opening above. Where that run is not there, you turn the stair into an L or U shape, or use a spiral as a last resort. A staircase cannot be made shorter in the same footprint without becoming too steep to be legal.
- Are my stairs too steep, and can you make them less steep?Stairs feel too steep when the pitch is close to or over the 42 degree legal maximum, and they are often that way because the space forced it. The catch is that making a stair shallower needs more floor length, not less, so you cannot shallow it in the same footprint. To genuinely fix a steep stair you have to open up the space, moving a wall, door, the floor opening or joists.
Ready when you are.
Free and no obligation. The Stair Guys survey the real space, never off a plan.