Most common mistakes in stair design

A concise list of mistakes that create discomfort or hazards — and how to fix them fast during design or review.

1 - Inconsistent risers

Small variations between riser heights in the same flight are a leading cause of trips. Humans detect rhythm; even 5-10 mm difference is enough to cause misstep.

Fix: Always check and enforce uniform riser heights. When remodeling, adjust finished thicknesses to keep risers consistent.

2 - Treads that are too shallow

Shallow treads give poor foot contact and a sense of instability. Less than 230 mm is usually unsafe; 250-280 mm is more comfortable for indoor use.

Fix: Increase tread depth where possible, or add landings or split flights to improve ergonomics.

3 - Ignoring the ergonomic formula

Designs that don't test 2 × rise + run often feel awkward. Either too many short steps or too few tall steps result.

Fix: Use the Stair Calculator to run step count variants until a candidate falls into the 600-640 mm band.

4 - Poor headroom and obstructions

Doors, soffits or beams encroaching into the headspace will create dangerous pinch points.

Fix: Check minimum headroom early (commonly ~2.0-2.1 m). Move ducts, or re-route if needed.

5 - Missing or incorrectly placed handrails

Handrails are vital for safety. Wrong height, interrupted rails or absent rails on open sides increase risk.

Fix: Provide continuous handrails at code height, with good grip and returns where required.

6 - Overly steep flights

Steep stairs (angles >42°) are uncomfortable and risky, especially for older users or children.

Fix: If run is constrained, insert a landing or break the flight into two; avoid steep single flights.

7 - Ignoring local code tolerances

Local codes often specify tolerances and limits (max riser, min tread, handrail requirements). Copying 'rule of thumb' without checking code invites failure at permit stage.

Fix: Always check the relevant national code early in the design process.

Quick audit checklist