Types of pools

The construction system of a pool determines much more than its shape or final finish. It directly affects key aspects such as overall cost, build time, long-term durability, and maintenance requirements. Understanding the differences between the various systems is essential before deciding which type of pool to build.

This article is part of our complete guide to swimming pools, where we cover construction systems, costs, and key technical criteria for choosing the right option.

What the system involves

Concrete pools are built on-site by constructing a reinforced concrete shell directly in the ground. There are two main methods: cast-in-place concrete, where concrete is poured into pre-built formwork, and shotcrete (gunite), where concrete is sprayed under pressure onto a steel framework. Both methods create a monolithic, permanent structure.

Advantages: design flexibility and structural strength

The use of concrete offers a high degree of design flexibility, allowing for custom shapes, varying depths, and integrated steps. It also provides strong structural performance, making it suitable for complex ground conditions and for pools intended for intensive or long-term use.

Drawbacks: cost, construction, and timelines

This type of pool involves a more complex build, with longer timelines and greater technical coordination. Initial costs are usually higher than prefabricated systems, and the final quality depends heavily on proper execution at every stage of construction.

You can explore the technical and construction aspects in more detail in our guide on concrete pools.

What the system involves

Prefabricated single-piece pools are manufactured entirely in a factory, typically using reinforced fiberglass, and then transported to the site for installation. The shell arrives fully finished and is placed into a pre-prepared excavation, significantly reducing on-site construction work.

Advantages: speed and simplicity

The main advantage of this system is the speed of installation, as the pool can be installed and operational within a few days. In addition, the fiberglass surface is inherently waterproof and requires relatively simple maintenance, with fewer joints and potential weak points.

Limitations: shape, size, and adaptability

As prefabricated units, shape and size are limited to the available models. They’re also less adaptable to complex ground conditions or difficult access, and any structural repairs are usually more complex than in a concrete pool.

If you want to dive deeper into this system, check out the guide on prefabricated monobloc pools.

En qué consiste el sistema

This type of pool is built using a modular structure—such as concrete blocks, steel panels, or other prefabricated systems—onto which a reinforced PVC liner is installed as the waterproofing layer and interior finish. The liner is welded on-site, adapting to the shape of the shell.

Advantages: balance between flexibility and cost

Modular pools offer a good balance between customization and cost, allowing more design flexibility than prefabricated fiberglass pools. The reinforced liner provides continuous waterproofing, can be repaired locally, and makes it possible to refresh the pool’s appearance without altering the structure.

Technical limitations: UV exposure, aging, and plasticizers

The liner is sensitive to UV radiation, so its durability largely depends on the quality of the UV stabilizers used during manufacturing. A low-quality liner can lose color, elasticity, and strength over time.

In addition, the flexibility of PVC depends on the type of plasticizers used. Higher-quality modern liners use phthalate-free polymeric plasticizers, with lower migration and better long-term stability. By contrast, lower-quality plasticizers can accelerate material hardening and, in some cases, raise concerns about potential toxicological impact if they don’t meet current regulations.

When they’re used

Above-ground and semi-inground pools are used when technical or planning constraints make full excavation difficult, such as sloped sites, rocky ground, or structural limitations. They’re also a good option when the goal is to reduce construction work and timelines.

Advantages: less site work and greater flexibility

Because they require less excavation, these systems can be installed more quickly and, in some cases, at a lower upfront cost. They can also be integrated into existing terraces or platforms and combined with modular, steel, or liner-based solutions.

Aesthetic and structural limitations

The main drawback is visual integration, as part of the structure remains visible. Proper structural design is also essential—especially for above-ground pools—to ensure stability, safety, and long-term durability.

Key differences in cost, time, and maintenance

Broadly speaking, concrete pools tend to involve higher upfront costs and longer build times, but offer a very robust solution. Prefabricated fiberglass pools stand out for their speed of installation and simplicity, while modular systems with liner usually sit in the middle, balancing construction, cost, and flexibility. In terms of maintenance, the key factors are the interior finish and how easy it is to intervene when issues arise.

Level of customization for each system

If the goal is to adapt the pool to a specific shape, integrate steps, or vary depths, concrete offers the greatest flexibility. Fiberglass is limited to existing molds and models, so customization is more restricted. Modular structures allow a fair amount of geometric adaptation, although the final result is still influenced by the structural system and the liner itself.

Lifespan and repairability

Lifespan depends on both the system and the quality of the finish and execution. In general, concrete can offer long durability, but it requires proper waterproofing and finishing choices. Fiberglass has a continuous, stable shell, though it may need specific repairs in case of impacts or gelcoat degradation. In liner pools, the key point is that the liner is replaceable: the structure can last many years, but the liner is typically renewed when it ages or loses its properties.

Intended use

The first thing to consider is how the pool will be used. For occasional family use, prefabricated or modular systems may be sufficient, while intensive or long-term use often justifies more robust solutions like a concrete pool.

Available space and ground conditions

Plot size, site access, and ground conditions directly influence the construction system. Complex sites—with slopes or irregular shapes—are usually better suited to concrete solutions, while simpler conditions allow for prefabricated or modular systems.

Budget, aesthetics, and long-term expectations

Beyond the initial cost, it’s important to consider long-term expectations in terms of durability, maintenance, and potential future interventions. In this context, the finishes offered by concrete pools are often seen as more premium, especially when using continuous materials and custom designs. Other systems can reduce the upfront investment, but with more limited aesthetic appeal and customization options.

If you’re deciding between traditional construction and a prefabricated shell, the comparison between concrete and prefabricated pools can help, where we break down practical differences in cost, timelines, and maintenance.
To see real solutions and completed projects across different construction systems, you can explore professional options at aqaspas.com.