What is box welding?
Box welding is a manufacturing process in which flat sheets of pond liner are cut and then hot-air welded at the corners and edges to produce a three-dimensional shape. The result is a liner that precisely mirrors the inside of your pond — every corner, every wall, every base angle.
Unlike a flat sheet liner, there is no excess material to fold away or tuck into corners. The liner simply drops in. There are no creases, no bunched pleats at the corners, and no guesswork about whether it will fit.
Why the shape matters
With a flat sheet liner, the excess material at the corners has to go somewhere. The result is a series of folds that, over time, can trap sediment, harbour algae, stress the liner at the fold points and, in the worst cases, cause premature failure.
A box welded liner eliminates all of that. When the pond liner is manufactured to your exact dimensions, every surface lies flat. The base is clean. The walls are taut. There are no corners to worry about because the liner already has corners, formed to match precisely.
This also means a faster, cleaner installation. You unfold the liner, lower it in to position. No wrestling with surplus material, no improvised folding techniques or no second-guessing.
The manufacturing process
Every liner we make follows the same five-step process:
- You send us your dimensions. Length, width, depth — and anything else relevant, such as steps, shelves or a coping lip allowance.
- We produce a technical drawing. A scale drawing of your liner, showing all the cut dimensions and weld positions. This is sent to you for approval.
- You approve the drawing. Nothing goes into production until you have signed off the drawing. This eliminates any risk of a liner being made to the wrong dimensions.
- We weld the liner. Our team cuts the pond liner sheet and weld each corner and edge using hot-air welding equipment, forming the three-dimensional shape.
- Delivery. The finished liner is folded flat, packed and dispatched to your address. Typical lead time is 5–10 working days from drawing approval.
Materials
We manufacture box welded pond liners in two grades of PVC, EPDM and Butyl pond liner:
- 0.75mm standard grade — Ideal for garden ponds, raised ponds and most domestic applications. Flexible, UV-stabilised and highly puncture-resistant.
- 1.0mm heavy duty — Recommended for larger ponds, koi ponds and commercial or high-traffic applications where additional durability is required.
Both grades carry a 25-year guarantee and are safe for fish and aquatic plants. Our PVC and Rubber pond liners are manufactured in Europe to consistent quality standards.