Pool linings fall into two categories. Waterproof linings provide both finish and waterproofing in a single layer – they can be applied to any pool structure. Decorative finishes are applied over a structure that has already been independently waterproofed –they offer greater aesthetic range but require a concrete or shotcrete base.
Waterproof linings
Three main waterproof lining options are used in high-end pool construction, each compatible with any pool structure, including concrete block.
Reinforced PVC membrane
The reinforced PVC membrane, sometimes referred to by trade names such as Renolit or Alkorplan, consists of a polyester mesh sandwiched between two PVC layers, giving a total thickness of around 1.5mm. Sheets are delivered in rolls and welded on-site by a specialist, allowing the membrane to adapt to any pool geometry including free-form pools.
Its lifespan is approximately 20 years, and it performs well in most climatic conditions. It is compatible with all pool structures – concrete, concrete block, or shotcrete.
Anti-slip: anti-slip versions are available with a textured surface, particularly for wet decks and shallow areas.
For infinity pools, zero-edge and overflow pools in general: the membrane can be used continuously across the basin, the gutter and the surge tank, which simplifies waterproofing at the junctions. However, the tight angles and curved profiles typical of overflow gutters require careful on-site welding; this is not a standard installation and must be carried out by an experienced applicator. The visual result, while functional, lacks the refinement of a hard finish on a high-end project.
Fiberglass reinforced polyester
Applied on site by specialists, fiberglass reinforced polyester, commonly referred to by its finishing layer, the gel coat, combines a glass fibre mat laminated with resin and a final colour coat. The result is a seamless, hard, slightly elastic surface that adheres partially to the structure.
The colour range is extensive and the finish quality is high. It is compatible with all pool shapes and structures, and is the reference finish for high-end concrete pools.
Anti-slip: an aggregate can be incorporated into the final gel coat layer before it cures, providing a controlled anti-slip surface without affecting the finish quality.
For any overflow pool: the gel coat can be applied continuously across the basin, the gutter and the wet deck, creating perfect visual continuity across the entire water surface. Its semi-adherent nature accommodates minor structural movement. It is our preferred waterproof finish for overflow pool projects.
Waterproofing render
Silico-marble render, a cement-based coat incorporating marble dust and additives, is used primarily on concrete pools. It provides waterproofing and a matte finish in a single application. It can be left as the final surface or used as a base for tiling.
Anti-slip: the naturally matte and slightly rough texture of render provides inherent anti-slip properties without additional treatment.
For infinity pools and zero-edge pools: render adheres fully to the structure. Any differential movement between the basin and the gutter risks cracking and leaking at the overflow edge. It is therefore not the preferred solution for overflow pool applications unless tile or stone is applied over it on a fully stable structure.
Decorative finishes
Decorative finishes require a concrete or shotcrete structure that is already waterproofed. They offer the widest aesthetic range and are the standard finish for luxury pool projects worldwide.
Mosaic and ceramic tile
Mosaic and ceramic tile are the most widely specified pool finishes globally and the default choice in many markets. Glass mosaic, small tiles of 20×20mm or 15×15mm pre-assembled on mesh backing, offers the richest colour range and the finest visual grain. Ceramic tile provides a more restrained palette at a lower price point. Enamel tile sits at the top of the range, with a satin surface and exceptional colour depth.
All tiled finishes are highly resistant to pool chemicals and temperature variation. The grout joints require periodic replacement, typically every ten years, and are sensitive to low pH water.
Anti-slip: tile and mosaic are specified with a minimum slip resistance rating for wet areas. For pool surrounds and wet decks, a textured or matte surface finish is selected over polished . The tile supplier specifies the relevant coefficient for each product.
For any overflow pool: tiling can be continued across the gutter and wet deck, creating visual continuity across the entire water surface. The grout joint pattern must be carefully considered at the overflow edge; a misaligned joint reads immediately against the water line. On curved or free-form overflow edges, mosaic is preferred over large-format tile for its adaptability.
Natural stone
Natural stone, slate, basalt, limestone, travertine, exotic stones such as Bali stone, is applied over a waterproofed concrete structure, either in slab form or, more recently, as stone veneer bonded to a composite backing of approximately 2mm thickness. The veneer format allows stone to be used on curved walls and submerged surfaces where full-thickness slabs would be impractical.
The aesthetic result is exceptional; natural variation in colour and texture gives each project a unique character that no manufactured finish can replicate.
Its long-term resistance to pool chemicals, UV exposure and frost varies by stone type and finish — this must be verified with the supplier before specification. It is a relatively recent application in pool construction and long-term data is still accumulating.
Anti-slip: stone finish is critical for safety. Polished stone is not suitable for pool surrounds or wet decks. Brushed, flamed or sandblasted finishes provide the necessary slip resistance — the choice between them affects both the tactile quality and the visual character of the surface.
For negative-edge pools: stone creates a particularly striking result on infinity pool edges and wet decks. The joint pattern and stone orientation at the overflow edge require careful detailing — the visual precision of the water line depends on it. Where the gutter is partially visible, stone veneer can extend the finish for visual continuity — but this applies to infinity pool configurations only, never to zero-edge pools where the gutter is concealed.
How the lining choice is determined
Four constraints determine the lining specification — and they must be resolved together, not independently.
Pool structure
For concrete, shotcrete and concrete block pools, fiberglass reinforced polyester, reinforced PVC membrane and silico-marble render can be applied directly. Tile and natural stone require a fully waterproofed substrate — this applies to concrete block structures and to any concrete structure that has not been poured monolithically.
Pool geometry
Free-form pools and pools with curved walls eliminate certain options immediately. Large-format tile cannot follow a curve without cutting. Fiberglass reinforced polyester and reinforced PVC membrane adapt to any geometry. Mosaic is the preferred tiled finish for curved pools — its small format handles complex geometry without visible distortion.
Climate and local resources
Frost cycles, UV exposure and water chemistry all affect lining longevity. Natural stone requires verification of frost resistance and chemical compatibility before specification. Render is sensitive to ground movement in unstable soils. Gel coat performs consistently across a wide range of climates and is regularly specified on projects in tropical, arid and temperate zones.
Local availability of materials and qualified applicators is an equally practical constraint — particularly on international projects. Fiberglass reinforced polyester and tiling can generally be sourced and installed locally in most markets. Reinforced PVC membrane requires a specialist welder, who may not be available in all regions. Natural stone specification depends entirely on what is locally available and at what quality level.
Aesthetics and water colour
The lining colour determines the water colour — and this is not a minor detail. A white or light grey gel coat produces a bright, luminous water surface. A dark finish — anthracite, black, deep blue — gives a reflective, mirror-like water that reads differently in every light condition. Natural stone introduces warmth and texture that no manufactured finish replicates.
For overflow pools, the lining colour at the overflow edge is amplified — the thin sheet of water catching the light intensifies whatever tone is beneath it. This effect should be tested with material samples on site before the final specification is confirmed.
Morana's advice
The lining is specified, not chosen.
Structure, geometry, climate, local resources and aesthetic intent all constrain the decision before personal preference enters the picture. On overflow pool projects, the lining must also be resolved across the basin, the gutter and the wet deck as a single continuous surface — not specified separately for each element.
No lining, regardless of material or thickness, compensates for poor substrate preparation or incorrect geometry. The masonry must be executed to the correct standard before any finish is applied. On overflow pools, where tolerances at the overflow edge are measured in millimetres, this is not a caveat — it is a prerequisite.
Conclusion
The lining appears last in construction sequence but must be decided early — during the design phase. It determines the water colour, the surface quality and the long-term character of the project. For overflow pools, it also defines the visual continuity between the basin, the overflow edge and the surrounding deck — a detail that separates a well-designed project from one that simply functions.
The right specification is always a combination of technical constraints and design intent. Where those two sets of requirements are resolved together from the outset, the result is a pool that performs as well as it looks — and continues to do so over time.