Step-by-Step Guide to Installing Reinforced Sheet Metal: Welding, Anchors, and Finishing Touches
The installation of reinforced liner combines industrial welding techniques with artisanal pattern-making expertise. Unlike a liner that is stretched over the pool, the reinforced liner is hot-welded to form a continuous surface tailored to the exact geometry of each pool. In this article, we detail the complete technical process, step by step, exactly as it is carried out on an actual job site.
Materials and Tools Required
For a professional installation, the following are required: reinforced PVC membrane (Renolit Alkorplan or another certified brand), perimeter anchoring profiles (AISI 304 stainless steel or reinforced PVC), shock-absorbing geotextile 200–300 g/m², the manufacturer’s sealing liquid, hot-air welding machines (manual and automatic), pressure rollers, welding test probes, structural repair mortar, and basic carpentry and masonry tools.
The items listed above must be owned by the certified installer. A company that asks the customer to “purchase the membrane” or “rent the welders” should not be hired for this type of project.
PHASE 1: Site Survey and Blueprints
Before any work begins, a technical site visit is conducted to measure the pool, assess the condition of the surface, and plan the layout. During this phase, the following are determined: actual dimensions (using a laser measuring tape), the number and arrangement of membrane panels, the direction of the seams, and the position of perimeter profiles and accessories. A detailed technical site visit prevents future problems and unforeseen issues during construction.
PHASE 2: Draining and Initial Assessment
The pool is drained using a submersible pump. The water is discharged into the sewer system or, if local regulations permit, into the garden after dechlorination. Once empty, the pool basin is inspected for: structural cracks, areas with deteriorated mortar, surface irregularities greater than 5 mm, damage to skimmers and inlets, and the condition of the perimeter metal sheeting (if present).
PHASE 3: Removal of the Previous Lining
Depending on the situation: if there was a liner, it is completely removed; if there were loose mosaic tiles, they are removed and the mortar is repaired; if there was paint, a deep cleaning is performed (sandblasting or pressure washing); if there was old reinforced sheet metal, it is removed. The surface must be clean and have sufficient adhesion to support the new installation.
PHASE 4: Structural Repairs
If there are cracks, they are sealed with hydraulic repair mortar or polyurethane resins, depending on their severity. Areas with loose mortar are chiseled out and replaced. Surface irregularities are leveled with leveling mortar. This phase is critical: a poorly prepared surface compromises the final result.
PHASE 5: Installation of Perimeter Profiles
The anchor profiles (stainless steel or PVC) are secured to the upper edge of the pool with specialized fasteners and sealant. These profiles serve as the physical “anchor” to which the membrane is secured around the perimeter. Precision in their placement (alignment, level, and spacing between fasteners) determines the final result.
PHASE 6: Installation of the geotextile
A layer of cushioning geotextile (nonwoven, 200–300 g/m²) is spread over the entire interior surface of the pool. This geotextile serves three functions: it cushions micro-irregularities in the substrate, protects the membrane from direct contact with the concrete, and improves thermal performance (it reduces the cold that the membrane absorbs from the basin).
PHASE 7: Pattern Cutting and Layout of Membrane Panels
The membrane panels are cut according to the calculated pattern (on-site or pre-cut at the factory for standard pools). They are laid out over the geotextile, leaving 4–5 cm overlaps at all seams. The operator verifies that the position is correct before beginning the welding.
PHASE 8: Hot Welding
This is the most technically demanding phase. It is performed using hot-air welding machines that apply temperatures between 350 and 450 °C to the overlap area, melting the two layers of PVC to create a seamless bond with the rest of the material. The welds are performed in two stages: first, a pass with an automatic machine (long, straight runs), followed by a manual touch-up with a small nozzle in critical areas (corners, angles, fittings).
STEP 9: Weld Inspection
Each weld is inspected using a test probe: a tool that is inserted into the welded joint and, by applying moderate pressure, confirms that the bond is continuous and free of gaps. Any weld that fails the test is redone immediately.
PHASE 10: Sealing Joints and Fittings
Perimeter joints (where the membrane meets profiles, skimmers, inlets, ladders, and lights) are sealed with the manufacturer’s liquid sealant (Alkorplan Liquid or equivalent). This liquid has the same chemical composition as the membrane and creates a permanent chemical seal. The metal or plastic frames for skimmers and inlets are also installed using the original fasteners and O-rings.
PHASE 11: Filling and Commissioning
The pool is filled with the filtration pump running to prevent air pockets from forming. As the water level rises, the liner conforms perfectly to the pool shell. Once full, the water chemistry is adjusted (pH 7.2–7.6, chlorine 1–3 ppm, alkalinity 80–120 ppm), and a complete initial filtration cycle is performed. The pool is now operational.
PHASE 12: Handover and Documentation to the Customer
The following is provided to the customer: a detailed invoice, an installation certificate signed by the certified installer, the liner’s technical data sheet with lot number and part number, maintenance recommendations, and warranty and support contact information.
Common Mistakes That Compromise the Result
The most common problems in poorly executed installations are: cold welds (insufficient temperature, layers do not fuse properly); misaligned profiles that cause localized stress on the membrane; improperly laid geotextile with wrinkles that transfer to the liner; incomplete sealing of perimeter joints, leading to future leaks; use of non-original sealant that does not form a chemical bond with the membrane.
All of these errors can be avoided with a certified and experienced installer. That is why it is essential to choose a company with a proven track record and official certification from the manufacturer.
Why Shouldn’t You Do It Yourself?
Installing reinforced membrane requires professional equipment (calibrated welding machines, precise measuring systems), specific technical knowledge (welding parameters based on material type and ambient temperature), and materials that are distributed only to certified professionals. A DIY attempt is highly likely to fail in the short term, voids any manufacturer’s warranty, and usually ends up being more expensive than hiring professionals from the start.
At ArgPiscinas, we perform all installations using our own Renolit Alkorplan-certified equipment. Request a free technical consultation at argpiscinas.es/contacto.
You may also be interested in
Renolit Alkorplan Reinforced Liner Collections: Which One to Choose · Alkorplan 3000: Stone- and Marble-Effect Reinforced Liner for Your Pool · Alkorplan 2000: Solid Colors for Your Pool (Standard Range)
https://www.argpiscinas.es/en/blog/instalacion-lamina-armada-paso-a-paso-soldadura