Planning
Common stair design mistakes to avoid
Stair design mistakes that surface late: fixing the step count too early, leaving headroom and openings until the end, and ignoring how people move around.
Choosing the step count too early
One of the most common stair design mistakes is fixing the step count first. The room, the opening and your comfort targets should all feed into that number.
Compare several counts and watch how riser height, going and pitch change together.
Leaving headroom until late
Headroom clashes hurt because they tend to appear after the stair already looks solved in plan.
Add the upper floor opening and slab thickness at the start, especially on a renovation.
Forgetting how people move around the stair
A stair sits in a room, and doors, landings, furniture routes and arrival direction all affect whether it works.
Before you finalize, picture someone carrying a box up and down the stair. That simple test exposes a lot of awkward layouts.
Put this into practice
Open the editor and test these numbers on your own staircase, with live drawings and a comfort score. No account needed.
Related guides
Planning
Stair headroom: what to check before building
How stair headroom depends on the floor opening, slab thickness and finishes, and the layout mistakes that cause clearance problems near the top of a flight.
Stair calculations
How to calculate stair rise and run
Work out stair riser height, going, pitch and total run from your floor-to-floor height, with the typical ranges to aim for before you build.
Comfort
Using the Blondel formula for comfortable stairs
What the Blondel formula (2h + g) measures, why the target sits near 600 to 640 mm, and how to use it to balance riser height and tread depth.