Quick comparison
| Criterion | Box welded | Flat sheet |
|---|---|---|
| Fit | Exact — manufactured to your pond dimensions | Approximate — excess material folded away |
| Installation | Drop-in. Unfold, lower in, position | Requires folding, pleating and securing on site |
| Creases | None — every surface lies flat | Inevitable at corners unless folded very carefully |
| Custom shapes | Any geometric shape — L-shape, steps, circles | Rectangular only without specialist cutting |
| Cost | Higher — reflects manufacturing process | Lower upfront |
| Best for | Permanent ponds, koi ponds, formal features, raised ponds | Informal wildlife ponds, temporary applications |
When to choose a box welded liner
Box welding is the right choice whenever fit and finish matter — which, for most permanent ponds, is most of the time. Specific situations where box weld excels:
- Koi ponds — where clean, crease-free walls are important for fish health and hygiene
- Formal garden ponds and water features — where the liner edge is visible and must look neat
- Raised ponds — where the liner must fold cleanly over the top edge of the structure
- L-shaped and stepped ponds — where a flat sheet simply cannot be made to fit without major improvisation
- Natural swimming pools — where size, shape and structural precision are critical
- Any situation where you want the installation to be quick, clean and correct first time
When flat sheet is perfectly fine
We sell box welded liners, so we have an obvious interest in recommending them. But in the interests of honesty, here are the situations where a flat sheet liner is a sensible, cost-effective choice:
- Informal wildlife ponds with organic, irregular shapes — box welding works with geometric forms; very freeform excavations suit a draped flat sheet
- Temporary or trial installations where budget is the primary concern
- Very shallow, wide ponds where the depth-to-footprint ratio means corner bunching is minimal
If you are unsure which is right for your project, call us. We're happy to give you an honest opinion — even if the answer is "flat sheet would do just as well for your pond."
Cost considerations
Box welded liners cost more than flat sheet because they take more time and skill to manufacture. Each liner is made to order — cut, positioned and welded by hand to your specific dimensions.
The factors that affect price are: total surface area of the liner, complexity of the shape (a basic rectangle costs less to weld than an L-shape with steps), the grade of PVC or Rubber (0.75mm or 1.0mm) and whether any special requirements apply (extra lip allowance, reinforced patches etc.).
We do not publish prices because every liner is different. The best approach is to request a quote with your dimensions — it takes two minutes and you'll have a price back the same working day.