Construction defect · Defects & construction flaws
Staircase defects: ergonomics, safety, fixings in new-builds
How to detect a staircase defect?
A compliant staircase respects precise dimensions: riser height between 17 and 20 cm, tread between 24 and 32 cm, Blondel formula (2h + g) between 60 and 64 cm. The handrail is at least 90 cm (1 m on upper floor), with balustrade spaced less than 11 cm to prevent a child passing through. Check: regularity of dimensions, firm fixings (screwed or sealed), no play at top and bottom of each step, non-slip surface, landing lighting.
Before — compliant
regular timber staircase · handrail 100cm
Blondel dimensions met · balustrade <11cm · screwed
⚠ After — defective
uneven step · handrail 82cm
Handrail below standard · wobbly step · to be reported
Reporting procedure in 4 steps
- 1Measure each stepRigid ruler or mason's rule. Note riser height, tread, width, Blondel formula. Photograph each irregularity with reference.
- 2Test the fixingsPress firmly on each step, on the handrail (80 kg horizontal push at the top). Any play or creak is abnormal.
- 3Formal noticeRegistered letter to the contractor within 90 days. Attach photos, measurements, regulatory references (NBN B 03-001 handrails Belgium).
- 4Adversarial expert assessmentIf disputed, independent structural expert. Admissible report · from €380 VAT incl. Cost recoverable if defect confirmed.
Who pays for the repair? Responsibility table
Depending on the nature of the defect, two-year warranty (finishes, fixings) or ten-year liability (unfitness for purpose, safety).
Defect type
Contractor
Owner
Insurance
Irregular riser height
✓ two-year warranty
—
—
Handrail < 90 cm
✓ ten-year liability
—
—
Balustrade spacing > 11 cm
✓ ten-year liability
—
—
Wobbly / loose step
✓ two-year warranty
—
—
Normal wear (post-2 years)
—
✓
—
Get an inspection
Independent inspection of your new staircase
Admissible report · 5-day turnaround · from €380 VAT incl.
FAQ
Common questions about staircases
My handrail is 88 cm tall. Is that legal?
No. The Belgian standard NBN B 03-001 requires 90 cm minimum on landing and 1 m on the upper floor. Any handrail below standard is a reportable defect on safety grounds.
My steps creak. Is it serious?
A creak reveals an insufficient fixing or wood shrinkage. Covered by the two-year warranty. Report by registered letter. Repair is done by re-screwing or re-gluing underneath.
The spacing between my balustrades is 13 cm. Problem?
Yes — major defect. Any child can pass their head through (strangulation risk). Standard: less than 11 cm. Have it reported without delay under ten-year liability (safety).
Does a spiral staircase follow the same standards?
Yes for the handrail and non-slip surface. Step dimensions are calculated on the walking line at 50 cm from the central post (riser 17-20 cm, tread 24-32 cm). A poorly designed spiral is more dangerous than a straight one.
How much does a full staircase replacement cost?
Between €2,500 and €8,000 VAT incl. depending on materials (wood, concrete, metal) and complexity. At the contractor's expense if construction defect. Keep invoices and plans.