Builder Defects List: The Most Expensive Problems Found

Not all defects are equal. Some are €40 to remedy. Some are €4,000. This is the builder defects list we focus on hardest during inspections — the high-cost items where missing them at handover means paying for them later.

1. Insulation Gaps

Most expensive long-term issue. Missing or displaced insulation in the attic costs energy every winter for the lifetime of the building. Easily fixed under warranty if caught; awkward to retrofit later.

2. Sealant Failures Around Wet Areas

A failed silicone seal around a shower or bath causes hidden water damage. Repair costs escalate fast once water reaches plasterboard or sub-floor.

3. Drainage Falls

Driveways or paths draining toward the house cause water ingress at thresholds. Re-laying surfaces is expensive; catching the issue at snag-list stage means the builder corrects it.

4. Render Cracking

Hairline cracks at openings can let in water. Left untreated, frost cycles widen them and the substrate behind suffers.

5. Missing Fire-Rated Detailing

Pipework and cabling penetrating fire-rated ceilings should have intumescent collars or fire-stop sealant. Missing detailing is a building regulation issue, not just a snag — and one builders should rectify immediately when flagged.

6. Heating System Commissioning

An incorrectly commissioned heating system runs inefficiently for years. Documented commissioning at handover protects your warranty and your bills.

7. Smoke and CO Alarm Commissioning

Alarms that aren't properly commissioned aren't doing their job. Easy to verify, easy to miss.