A swimming pool is now an almost standard feature of homes in the Alpes-Maritimes and Var. But a poorly built or poorly sited pool can crack, lose water, or become deformed under ground pressure. These issues, often costly to fix, are almost always the result of a workmanship defect or negligence during construction.
Structural causes of pool cracks
- Unstable or clay-rich soil: clay shrink-swell movement shifts the pool shell and cracks the structure.
- Lack of drainage: groundwater pressure (uplift) can lift or crack the pool shell.
- Poorly compacted backfill around the pool: differential settlement.
- Insufficient or misplaced reinforcement: the concrete cannot withstand the loads.
- Nearby vegetation: tree roots destabilise the soil.
Waterproofing defects
- Poorly fitted liner (creases, punctures) on liner pools.
- Waterproof coating (tiling, epoxy paint) poorly applied or unsuitable.
- Fittings (skimmers, inlets, lights) poorly sealed: leaks.
- Missing expansion joint between the deck and the pool shell.
Warning signs to watch for
- Abnormal drop in water level: leak or cracking.
- Cracks in the floor slab, walls or coping.
- Tiles lifting or blistering appearing on the liner.
- Sinking of the surrounding deck.
- Visible tilting or deformation of the walls.
Diagnosis and remedies
A cracked pool requires a precise diagnosis: locating leaks (fill test, dye test, camera inspection), and analysis of the structure and soil. The building expert determines the cause (workmanship defect, soil, drainage) and estimates the cost of repair (injection, waterproofing repair, structural repair, sometimes partial demolition). If the pool is part of a recent purchase, the issue may fall under the 10-year builder’s warranty (structural soundness compromised). In case of a dispute with the pool builder, see our guide on defects discovered during construction.
📅 Updated on 27/08/2026 — By Cassini Expertise, independent building expert for the Alpes-Maritimes & Var. Free quote: 04 22 46 06 04.
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Frequently asked questions
My pool is cracking, what should I do?
If your pool is cracking, it is crucial to act quickly to prevent the problem from worsening. Call in a waterproofing expert to diagnose the cause (structural, hydraulic or workmanship) and propose a suitable solution (injection, resin, or reconstruction).
How do you repair a crack in a concrete pool?
The repair depends on the nature of the crack. For fine, non-structural cracks, a polyurethane sealant or epoxy resin can be used after cleaning. For larger or through-cracks, pressure resin injection is required, sometimes followed by a waterproofing membrane.
What are the common defects that cause cracks?
Common defects include poor soil preparation, insufficient reinforcement, low-quality concrete, faulty drainage, or unanticipated ground movement. A waterproofing defect at corners or penetrations can also cause cracking.