Liner calculator
Liner calculator
Most liner gets ordered on a guess, and the guess is nearly always short — because people measure the base and forget the slope faces and the anchor trench. Give this the three dimensions and the batter and it does the geometry properly, then prices the panel and the protection fleece and drops both into your basket.
How to use it
- 01
Measure the base
Base length, base width and the depth at the deepest point.
- 02
Set the batter
The side slope your design uses — 1 in 2 is the usual basin.
- 03
Add it to the basket
Panel priced per m², plus the fleece to go under and over it.
What are you lining?
Crate block, fully encapsulated — base, four walls and a top.
Base dimensions & depth
Sheet overlap
Waste allowance
Corners fold away membrane, and deeper tanks lose more. We allow 25% on our own tank jobs.
Layers
Add a second geotextile layer if the membrane needs protecting on both faces.
Material
Reinforced HDPE. Made in one piece to your finished size.
Liner to order
732m²
Total ex VAT
£3,872.28
£4,646.74 inc VAT
- Before waste
- 585.6m² per layer
- Geotextile
- 732m² (1 layer)
- Or as rolls
- 7 × 2.5m × 50m roll, HDPE 0.6mm
- Delivery
- + £225.00 ex VAT, once per order
Show the working
- Base 20 × 12 = 240m²
- Walls 2 × (20 + 12) × 1.5 = 96m²
- Top 20 × 12 = 240m²
- Laps 2 × (20 + 12) × 0.15m = 9.6m²
- Total = 585.6m²
- + 25% waste allowance = 732m² per layer
- Membrane: 1 × 732 = 732m²
- Geotextile: 1 × 732 = 732m²
Ponds of any plan shape, wrapped tanks, car park sub-bases and flat areas are covered here. Anything terraced or heavily penetrated — send the drawing and we'll work it out from that.
Questions
Frequently asked questions
Because a liner isn't flat. It has to travel down the side slopes, which are longer than the vertical depth, and it has to carry on into an anchor trench at the top so it can be held down and trimmed. On a 1 in 2 batter, every metre of depth costs 2.24m of liner per side.
500mm per edge is the sensible default — a 300mm anchor trench plus margin for trimming. Drop to 300mm on a tight, well-surveyed job; go to 750mm where levels are uncertain or the perimeter detail is complicated.
If you're fleecing both faces, yes — under the membrane to protect it from the formation, over it to protect it from the backfill. It's the cheapest line on a lining job and the one most likely to get value-engineered out, which is why liners tend to fail during backfill rather than in service.
The calculator covers rectangular basins, wrapped tanks and flat areas, which is most of what gets ordered. Anything shaped, terraced or with a lot of penetrations, send us the drawing and we'll fabricate to a bespoke pattern and price it properly.
Usually. We weld the seams in factory conditions and air-test every one of them, so what arrives on your site is a single sheet that unfolds into the hole — fewer site seams, less time in the trench and fewer places to fail. Rolls make sense where the area is big enough to need site jointing anyway.
Tell us about your project
Quote back within one working day