Reinforced PVC membrane: how it is made and how it is installed
A reinforced membrane is a PVC sheet with a built-in fibre mesh, laid in strips and hot-air welded inside the pool. It is tougher and more stable than a simple, ready-made liner.
What "reinforced" means
A reinforced membrane is made of layers of PVC with a polyester fibre mesh between them. The PVC provides watertightness, colour and a smooth or textured surface. The mesh provides tensile strength and keeps the dimensions stable, much like the fabric inside a good garden hose.
In practice, the reinforcement means:
- Resistance to tears and punctures: the mesh stops minor damage before it spreads.
- Dimensional stability: the membrane does not easily swell or shrink with heat or chemicals, so it wrinkles far less.
- Tolerance of small movements in the ground and the structure, without cracking.
- Precise detailing: it is cut and shaped on site around steps, benches and corners.
The liner of our prefab pools is 1.5 mm PVC with internal fibre reinforcement and a written 10-year guarantee. SOPREMAPOOL membranes are also reinforced: the 3D is 1.8 mm thick with a three-dimensional textured finish, and the Feeling is 1.5 mm in a solid colour. Both are Class C anti-slip, with a lacquer that resists UV radiation and chlorine.
Hot-air welding on site
A reinforced membrane does not arrive pre-shaped to the pool. It comes in rolls and is formed inside the pool, usually in this order:
- A protective underlay is spread over the floor and walls so that the membrane does not rest on sharp points or uneven spots.
- Special profiles are fixed around the perimeter, and the membrane is attached to them at the edge.
- The strips are cut to size, overlapped by a few centimeters and welded with a hot-air tool, which melts the surface of both sheets and fuses them into one.
- Every seam is checked along its full length and is usually sealed with liquid PVC in the same colour.
- Finally, the openings for the fittings are cut and the face plates and sealing gaskets are installed.
Welding needs dry weather and an experienced hand: a good seam is just as strong as the rest of the membrane. Because everything is done on site, the membrane fits precisely over built-in steps, benches and shapes such as an L, without the folds a ready-made piece would leave.
Reinforced membrane or ready-made bag liner
The word "liner" is used for both, but they are different products:
| Reinforced membrane | Ready-made bag liner | |
|---|---|---|
| Material | PVC with fibre mesh | Plain PVC without reinforcement, usually thinner |
| Fabrication | Cut and welded inside the pool | Welded at the factory to the pool's dimensions |
| Fixing | Welded to perimeter profiles | Hangs from a track at the edge |
| Steps, benches, special shapes | Covered precisely | Limited options |
| Wrinkles | Rare, thanks to its stability | More likely when chemistry or water level is out of range |
A ready-made liner has its place in simple rectangular pools with no special features. A reinforced membrane is the solution when you want greater durability and design freedom.
When it is chosen
- When the pool has built-in steps, a bench or a shape beyond a simple rectangle.
- When you want an anti-slip surface on steps and benches, for children and older people.
- In pools at guest accommodation, with many swimmers and heavy use.
- When you want the longest possible lifespan; see how long each part lasts in the lifespan of a prefab pool.
For how the membrane, the fittings and their gaskets work together to make a watertight pool, see pool watertightness.
Questions
How can I tell whether I'm being offered a reinforced membrane or a plain liner?
Ask about the thickness, whether there is an internal fibre mesh, and how it is installed: welded on site, or a ready-made piece hung from the edge. Also ask for the guarantee in writing.
Can a reinforced membrane go into an old pool that had a bag liner?
Usually yes, but it depends on the condition of the walls, the floor and the fittings. This is checked at the site survey, as we explain in liner replacement.
See also
Pool lining
Prefab pool lining with a 1.5 mm PVC liner and a written 10-year warranty, or with non-slip SOPREMAPOOL 3D…
Anti-slip surface
Anti-slip surface for pool steps and benches: what Class C means, which membranes have it, and why it matters…
Pool watertightness
Watertightness of a prefab pool: how the liner provides it, how skimmers, return inlets and lights are…