Why a zero-edge configuration is the natural choice for indoor pools
An outdoor overflow pool with a cascade edge draws the eye toward the horizon – that is its purpose. Indoors, there is no horizon. The gaze meets walls, ceiling and the architecture of the enclosed space. This is why the zero-edge configuration, water level flush with the deck on all four sides, is the natural choice for an indoor pool. The still water surface reflects the surrounding architecture, extends the visual space and creates a continuity between the pool and the living environment.
The zero-edge configuration also brings a decisive hydraulic advantage indoors. The upward circulation created by floor return inlets distributes heat and disinfection products evenly throughout the full water volume. In an enclosed space where heating is a major energy expenditure, a well-circulated body of water reaches and holds its temperature more efficiently than a skimmer pool, where hydraulic dead zones create thermal disparities and uneven distribution of treatment products.
Deck slopes and water runoff around the basin
In an outdoor pool, water that overflows or splashes onto the deck runs off naturally into the garden. Indoors, every litre of water must be directed with precision. The decks around the basin must be designed with calculated slopes that channel runoff toward collection gutters, preventing any water accumulation on the interior floor surface.
This constraint directly affects the choice of deck finish. A surface too smooth without adequate slope creates stagnant zones. A surface too rough, or slopes too pronounced, compromises comfort of use. The balance is established in the execution drawings, where every level is defined before the concrete is poured.
Acoustic and thermal insulation
The plant room for an indoor pool is often integrated within the building envelope, close to living spaces. Pumps can generate vibrations and a low-level background noise that – for people sensitive to sound – is perceived differently in an enclosed space than outdoors. A well-designed plant room integrates anti-vibration mounts under the equipment and sound-absorbing materials on the walls to limit noise transmission through the building structure.
The heat pump, which typically provides heating for this type of project, is positioned outdoors. This naturally resolves the noise question and simplifies the layout of the interior plant room.
Thermal insulation is equally critical. An interior space heated continuously loses heat rapidly if the building envelope is not treated. Thermal bridges between the pool structure, the walls and the roof must be identified and addressed during the structural design phase.
Dehumidification: a sanitary and structural priority
An indoor pool generates continuous evaporation. This phenomenon intensifies when the water temperature is noticeably higher than the ambient air temperature: the greater the gap, the more evaporation occurs. Maintaining air temperature close to water temperature reduces this gap but increases the energy consumption of the space. Covering the pool when not in use, even indoors, which may seem counter-intuitive, is one of the most effective ways to limit evaporation and reduce the load on the dehumidification system.
Without adequate dehumidification, air saturated with moisture becomes difficult to heat efficiently and creates conditions favourable to mould growth on walls, joinery and building structure. These problems are costly and difficult to correct once the project is delivered.
The dehumidification system must be sized according to the water surface area, the water and air temperatures, and the volume of the interior space. It is an integral part of the design brief, at the same level as the filtration or heating of the pool itself.
Integrating a spa: a complete year-round wellness space
An indoor pool creates ideal conditions for the integration of a spa. The environment is already heated, the humidity is managed, the plant room is in place. Adding a spa in this context does not represent a disproportionate additional cost compared to an outdoor project, and transforms the space into a year-round wellness environment usable in any weather.
The spa integration must be anticipated at the design stage. Its hydraulic circuit, heating system, and position relative to the main pool directly affect the technical drawings.
Regulatory framework
The creation of an indoor pool is generally part of a broader architectural project : an extension, restructuring or modification of the existing building. Administrative requirements depend on the local context and must be verified with the relevant authorities before any design commitment.
Morana’s advice
An indoor pool is not a basin under a roof. The building envelope, air management, deck slopes and acoustic insulation condition every decision that follows. These parameters are fixed at the design stage – correcting a dehumidification failure or a badly calculated slope after the concrete is poured is either impossible or very costly. This is why an indoor pool project requires a global reading of the site long before the first line is drawn on the plan.
Frequently Asked Questions – Indoor infinity pool
Is an indoor infinity pool feasible in any building?
Not automatically. An indoor infinity pool requires specific structural, hydraulic and environmental conditions – reinforced structure to support the water volume, dedicated plant room, controlled ventilation and dehumidification, thermal insulation of the building envelope. In an existing building, these requirements are assessed at feasibility stage. In a new construction, they are integrated into the architectural brief from the outset.
Does an indoor pool require a different filtration system than an outdoor pool?
The filtration equipment itself is the same, but the sizing may differ. Indoor pools are typically maintained at higher temperatures than outdoor pools, which accelerates chemical consumption and increases the demand on the treatment circuit. UV or ozone treatment is often preferred to chlorine, as it reduces the release of chloramines into the enclosed air. These specifications are decided at the design stage as part of the overall hydraulic study.
