Construction defect · Defects & construction flaws
Structural cracks in a new-build: detect, prove, get repaired
How to detect a structural crack?
Not all cracks are equal. A shrinkage hairline crack (under 0.2 mm) is cosmetic and linked to materials setting during the first months. A structural crack (over 2 mm, evolving, or through the wall) compromises building stability and triggers the ten-year liability. Distinguishing the two determines the procedure and applicable warranty. The method: measure width with a crack gauge, photograph with a rigid ruler, and place a plaster witness to monitor evolution over 30 days.
Before — benign
cosmetic hairline crack < 0.2mm
Mortar shrinkage · cosmetic repair sufficient
⚠ After — structural
through-crack 4mm with offset
Evolving · report immediately
Reporting procedure in 4 steps
A structural crack falls under the ten-year liability (Article 1792 of the Civil Code, applicable in Belgium). The reporting deadline is short (90 days in practice) and the procedure must be documented. Here is the step-by-step approach.
- 1Photograph and measureHD photo with a rigid ruler or crack gauge. Measure width, length, depth. Note date, weather conditions, and precise location (wall, floor, orientation, exact spot in the home).
- 2Place a witnessA plaster witness across the crack proves its evolution over time. Place it on the date of discovery, check at 30 days minimum. Photograph the witness at start and at each check.
- 3Formal noticeRegistered letter with acknowledgement of receipt to the contractor within 90 days of discovery. Attach dated photos, measurements, and technical description. Template available in our formal notice to contractor cluster.
- 4Adversarial expert assessmentIf the contractor disputes, commission an independent expert. Cost recoverable if defect confirmed (typically between 380 and 650 euros depending on complexity). The expert produces an adversarial report admissible in court.
Who pays for the repair? Responsibility table
Repair responsibility depends on the type of crack and its origin. Here are the main scenarios for a new-build in Belgium under the Breyne Law regime and ten-year liability.
Crack type
Contractor
Owner
Insurance
Shrinkage crack < 0.2 mm
—
✓ cosmetic
—
Non-through render crack
✓ two-year warranty
—
—
Structural crack 2-5 mm
✓ ten-year liability
—
ARI if applicable
Evolving through-crack
✓ ten-year liability
—
✓ ARI + structural damage
Soil defect (missing survey)
✓ + architect
—
Architect PI
Get an inspection
Have these cracks inspected by an independent expert
Adversarial report admissible in court · 5-day turnaround · from €380 VAT incl.
FAQ
Common questions about cracks
A hairline crack has appeared in my new home. Should I worry?
A hairline crack (under 0.2 mm) is generally linked to material shrinkage during the first year. Monitor it with a plaster witness. If it evolves or exceeds 0.5 mm within 6 months, have it assessed without delay.
How long do I have to report a structural crack?
The ten-year liability covers defects for 10 years from final reception. But in practice, report within 90 days of discovery by registered letter to preserve all your options and avoid forfeiture for late reporting.
My contractor says it is a normal defect. What should I do?
Any crack wider than 2 mm, through the wall or evolving is NOT a normal defect. Obtain an adversarial assessment by an independent expert. Their report is admissible even if the contractor disputes it. Our expert service intervenes within 5 days.
How much does an independent crack inspection cost?
Between €380 and €650 VAT incl. depending on case complexity (number of cracks, continuous monitoring, possible geotechnical expertise). This cost is recoverable from the contractor if the defect is confirmed.
If the expert assessment confirms a structural defect, what is covered?
Full repair, at the contractor's expense via their ten-year liability. If the origin is an undetected soil defect, responsibility may be shared with the architect (PI insurance). If the contractor is bankrupt, the construction all-risks (ARI) and structural-damage insurance may take over.
Does a crack make my house uninhabitable?
Except in exceptional cases (imminent collapse confirmed), no. But it can affect resale value and requires prompt repairs. Document everything: dated photos, expert report, written exchanges with the contractor. This documentation will be key in any dispute.