Piscina AlkorPlan2000
Courtesy Renolit Piscina AlkorPlan2000

As commercial aquatics facilities re-open after the pandemic closures, managers and operators might have found themselves confronted with peeling, cracking or leaking pools. A viable solution to these chronic problems is to line these pools with a PVC membrane.

Most facility managers and operators find the price of the membrane very affordable. When considering this option, it’s important to consider the costs of refinishing or repairing the pools versus installing a PVC membrane. Some underlying issues with a pool’s structure can be eliminated by using a PVC membrane to create a complete watertight structure throughout the pool.

The membrane can offer a complete waterproofing solution, as it completely seals the structure of the pool and keeps it watertight, making it suitable for both renovating existing pools and building new installations. They can be used to finish off a new concrete wall or stainless-steel pool wall construction, or if you are covering a cracked, peeling, or leaking gunite or fiberglass pool.

In addition, they are not susceptible to deterioration from acidic water conditions. Commercial-grade reinforced PVC membranes are coated with a protective lacquer that enhances durability to tear, resistance to chemical abuse, water absorption and UV resilience.

PVC membranes can offer another, more immediate benefit: Rather than dealing with long lead times for pre-manufactured products, weld-in-place membrane materials are readily available. Installers can overcome lead times by stocking the PVC for upcoming jobs.

The weld-in-place liners are uniquely able to provide a perfect fit for custom pools because they are installed on-site, even for the most challenging shapes, so you get an exact fit. The 60- and 80-mil mesh reinforced PVC (polyvinyl chloride) adds to the longevity.

Once these PVC membranes are installed, the surface underneath can continue to shift and crack but it won’t affect the membrane. And the materials is covered by warranties up to 20 years. Not only does it solve a problem for the aquatics facility, but it also makes maintaining the pool easier for commercial parks and recreation aquatic facilities.

Not only are they practical but they now also come in beautiful textures that will give pools a completely renovated look.

For attractiveness’ sake, these membranes can be found in various textures and even prints that resemble marble, stone and sand. These options have been popular with hotels, country clubs, homeowners associations and community pools because they provide a more high-end feel, going beyond the plain white or blue, while enhancing safety through the slip resistance offered by textures.

Understanding PVC Membrane Installation

The installation process of a PVC membrane is relatively straightforward.

Before installing the membrane, crews prepare the surface, which can include repairs. Most pools require a day or less for preparation, however if a pool is in particularly bad shape, a professional might need to spend three to four days patching the pool, fixing returns, etc.

Once the surface is prepared, a felt-lining is installed along the floor and walls of the pool structure. This material, also referred to as geotextile, acts as an anti-bacterial to avoid bacteria proliferation behind the membrane, to extend the life of the product. As a side benefit, the felt lining makes the floor more comfortable to stand on. This is especially beneficial to older bathers using the pool for water conditioning, therapy or aerobics. Patrons at small wading pools that feature a PVC membrane regularly report that they love the cushioned feeling of the surface.

After the geotextile is installed, 6-foot-wide strips of PVC membrane are rolled out and heat-welded together on site to ensure a perfect, smooth fit. Steps, beach entries, safety ledges and the like are cut, fitted and welded as well.

Some membranes are available with slip-resistant, embossed surfaces, which are generally used on steps, in shallow areas and beach entries. Black material is also available to create racing lanes, transitions and depth markers as needed.

Welding Techniques

A major benefit of the weld-in-place liner is its ability to be fabricated on site. This allows the greatest degree of customization, and can help with current supply-chain issues, as it removes a step from the manufacturing process.

To ensure proper fit, durability and water-tightness, installers use three different welding techniques in different parts of the installation process.

The two basic techniques — spot welding and traditional overlap welding — are used by all contractors and achieve a water-tight liner. Installers looking for a superior aesthetic also use the “butt-welding” technique along the pool floor to make the welds virtually invisible.

Spot welding: This technique is used at the beginning of installation to help position and secure the membrane, so it doesn’t move through the rest of the process.

Small, quick ‘pre-welds’ are made between the overlapping membrane layers at intervals of approximately 7 to 8 inches down the seam. Even though this is a “tack weld,” the pieces must be perfectly aligned, and the membrane cannot move.

Overlap welding: The membrane layers overlap by approximately 2 inches. This overlap will ultimately turn into a 2-inch-wide seam.

Once the membrane is held in place with the spot welds, installers begin to apply the welding gun down the full length of the seam. They insert the welding nozzle under the overlap and heat both surfaces sufficiently to fuse the layers and form a lap.

While the lap is still hot, they use a silicone roller to apply enough pressure to ensure the two membranes are pressed and fused together.

For larger pools, robot welders are used to automate and speed up the welding process. Once the automatic welder is set-up it will continue welding for the entire length of the pool.

Butt welding: This technique, compatible only with 80mil membranes, is used in more visible areas of the pool where a seam would be easily detected, such as the horizontal pool floor. To do this, installers butt the membrane edges against one another, rather than overlapping them.

When this technique is used, viewers cannot see the joints where the PVC membranes meet on the floor. This particularly makes a difference at night, when the pool water is illuminated by in-pool lighting. In the daytime, when the water is moving, the traditional overlap welding is not apparent.

This technique is not required by any means, though it achieves absolute flatness with virtually invisible joints both by day and by night. Because it takes more time and will add to installation costs, it is only recommended for the floor area. Some installers stick with the overlap weld here as well.

Membranes On the Rise

The awareness of PVC membranes is definitely on the rise, especially among commercial aquatics facilities. In fact, most architects and aquatic consultants now are starting to require the use of PVC membranes in high-rises or anywhere the waterproofing of the pool must be guaranteed. In general, we find it becoming more common for facility managers to approach their trusted pool professional to provide this solution after performing their research.

As a result, pool professionals are finding it even easier to suggest, sell, install and outsource the installation of these membranes to commercial pools.