Why do swimming pool tiles come loose — and how to stop it?
Detaching tiles are often dismissed as 'just old age', but in reality, the problem always has one or more concrete, technical causes. Those who understand the mechanics will also see why a renovation to a closed coating such as ACRATON® Dolphin structurally solves the problem instead of temporarily hiding it.
On this page, we will discuss the four dominant causes that we have seen almost without exception in 30 years of PoolFIX practice — and how an ACRATON® renovation addresses all four.
Cause 1 — Chloride Attack of Cement Mortar
Chlorine and chloramines slowly attack cement-bound mortar materials through a process called 'decalcification'. The lime in the mortar reacts with chlorine compounds to form soluble salts that wash away, weakening the mortar and causing adhesion to the tile to be lost. After 10–15 years, this process is measurable in every public pool — and visible in loose tiles.
Cause 2 — Differences in Thermal Expansion
Concrete, mortar, and ceramics have different coefficients of thermal expansion. In an outdoor pool that fluctuates between 5 °C in winter and 30 °C in summer, continuous micromechanical stresses arise between the tile, grout, and substrate. Adhesion breaks at the weakest point — and that is usually the mortar-tile interface.
Cause 3 — Freeze-Thaw Cycles (Outdoor Pools)
For outdoor pools, frost damage is an additional factor: water trapped in joints expands by 9 % when frozen and gradually breaks down the grout. After 5–10 winters, the pattern is recognisable: loose grout, cracked tile edges, and localised hollow spots.
Cause 4 — Hydration and Mechanical Stress
Finally, absorption plays a role. Cement mortar absorbs water during the swimming season, expands by several tenths of a millimetre, and shrinks again upon drainage. This cycle, combined with the mechanical stress from swimmers, brushes, and vacuum cleaners, fatigues the material year after year.
Why a Coating Solves All Four
A 2-component epoxy such as ACRATON® Dolphin is chemically closed (non-porous), chemically resistant to chlorine and chloramines, not subject to frost damage, and has an expansion coefficient compatible with the concrete substrate. This eliminates the mechanical weaknesses — joints — and addresses all four main causes in one intervention.
Calculate volume for your pool
Litres, pails and price estimate in seconds — pallet discount included.
Prices exclude VAT and shipping. Based on €40/L and the theoretical coverage from the datasheet (2.7 m²/L at 300 µm DFT).
Frequently asked questions
Can I prevent chloride attack by using less chlorine?
Is simply re-grouting not sufficient?
Do mosaic tiles suffer less?
Does this also apply to modern tiles (low water absorption)?
What is the difference between cement-based and epoxy-based grouts?
How do I know if my pool is ready for renovation?
Slight deviations between sample and final result may occur. No rights can be derived from this overview.
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