Built-in spa and jacuzzi with reinforced membrane: integrated wellness in your pool
Building a built-in spa or jacuzzi with reinforced membrane is the best way to integrate a hydromassage wellness area into your pool without sacrificing the reliability of professional waterproofing. Unlike traditional mosaic tiles, Renolit Alkorplan reinforced membrane (1.5 mm armoured PVC reinforced with a polyester mesh) adapts to the steps, submerged seats, curves and complex geometries that define a built-in spa, sealing every corner through hot-air welding and eliminating the risk of leaks at the joints. At ARG Piscinas, official reinforced membrane installers with over 15 years of experience in Andalusia and across Spain, we build spa and wellness areas perfectly integrated with the main pool.
Why choose a reinforced membrane for a built-in spa or jacuzzi
A built-in spa is not a simple rectangular tank: it includes ergonomic seats, access steps, niches for the hydromassage jets, level changes and often curved or kidney shapes. All these surfaces are critical points where pressurised water and high temperatures (35-38 ºC) place constant stress on the lining. The reinforced membrane solves this challenge because:
- It adapts to any shape: the armoured PVC membrane conforms over seats, curves and steps with no need for cuts or special pieces.
- Continuous, watertight welding: overlaps are joined with hot air, creating a monolithic surface with no cement joints that degrade with heat.
- Thermal resistance: Renolit Alkorplan is formulated to withstand the thermal shocks of hot hydromassage water without cracking or peeling.
- Pleasant touch: a smooth, warm surface, ideal for an area where the body is in prolonged contact with the seats.
Waterproofing steps, seats and curves without cracks
The real technical challenge of a spa lies in its complex shapes. Every step, every seat and every change of plane is an area where traditional mosaic accumulates stress and eventually cracks. With the reinforced membrane, our team works the membrane in sections: the layout of each surface is planned, the membranes are overlapped following the geometry of the seat or step, and the angled joints are welded with precision. On the inner and outer edges we apply finishing profiles and a liquid sealing bead to guarantee total watertightness even at the most exposed points.
Beneath the membrane we always place a protective geotextile that absorbs small irregularities in the substrate and isolates the membrane from concrete cracks, extending its service life. This detail, invisible once the work is finished, makes the difference between an installation that lasts 20 years and one that fails within a few seasons. See real examples in our gallery of pool and spa projects.
Wellness area integrated with the main pool
The great advantage of lining spa and pool with the same system is the aesthetic and technical continuity. By integrating the wellness area with the main tank, both share colour, texture and, if the design allows, an overflow channel or separating wall waterproofed continuously. This creates a visually harmonious set and, above all, a hydraulically coherent one: the water overflowing from the spa into the pool does so over equally watertight surfaces.
Renolit Alkorplan offers a wide range of finishes —from sand and grey tones to stone or mosaic effects— that let you visually distinguish the hydromassage area without breaking the unity of the set. If you start from an existing pool and want to add a spa, we approach it as a reinforced membrane installation for new construction for the extended area, integrating it with the lining of the main tank.
Hydromassage: jets, pressure and technical details
The hydromassage adds complexity: every supply jet, every suction and every air blower is a penetration that crosses the lining. The reinforced membrane allows these passages to be sealed with flanges that clamp the membrane against the body of the jet, ensuring watertightness even with pressurised water. Some aspects we take care of in every spa:
| Element | Technical solution |
|---|---|
| Hydromassage jets | Flange with gasket and welded overlap around the body |
| Submerged seats | Membrane shaped in one piece with welding on the edges |
| Access steps | Calculated overlaps and finishing profile on each step |
| Spa-pool junction | Continuous waterproofing over the overflow wall |
We always coordinate the membrane installation with the plumbing and the hydromassage machinery so that each passage is perfectly sealed. Discover all our reinforced membrane services for pools and spas.
Refurbishing a mosaic spa with reinforced membrane
If you already have a built-in spa or jacuzzi lined with mosaic that leaks, cracks or shows stains impossible to clean, there is no need to demolish it. The reinforced membrane is installed directly over the existing mosaic, restoring watertightness and renewing the finish without aggressive works. It is the ideal solution for old spas where the cement joints have failed due to heat and hydromassage pressure. We explain it in detail in our service for reinforced membrane installation in old pools and in liner replacement and accessory refurbishment.
Frequently asked questions
Does the reinforced membrane withstand the hot spa water?
Yes. Renolit Alkorplan is designed to withstand spa temperatures of 35-38 ºC continuously. The armoured PVC keeps its elasticity and adhesion against thermal shocks, something mosaic cannot guarantee because of the rigidity of its joints.
Can the reinforced membrane be installed on curved seats and steps?
Of course. The membrane is shaped and welded over any geometry: ergonomic seats, steps, curves and level changes. Hot-air welding creates a continuous surface with no joints that adapts to the most complex shapes.
How long does a spa lined with reinforced membrane last?
With professional installation and basic maintenance, the reinforced membrane has a service life of 15 to 20 years or more. The protective geotextile and continuous welding are key to that durability.
Can I integrate the spa with a pool I already have?
Yes. We line the new spa area with the same system and integrate it visually and hydraulically with the existing tank, achieving a homogeneous and fully watertight wellness set.
Do you want a wellness area with a built-in spa or jacuzzi perfectly integrated with your pool? At ARG Piscinas we design and install your spa with Renolit Alkorplan reinforced membrane in Andalusia and across Spain. Request your no-obligation quote or call us on +34 697 26 12 48: we advise you free of charge.
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