Protective Matting is always recommended with any type of pond liner
Although both PVC and EPDM pond liners are strong and durable, they can occasionally be pierced by sharp objects such as stones, tree roots or other abrasive items in the ground around the pond. So, how do you prevent this from happening?
Location: Ponds are best located a short distance away from any trees or large bushes as their roots may extend outwards some way away from the trunk. As the tree or bush grows, the root system will also extend, so leaving space will help to futureproof your pond.
Preparation: When digging the hole for your pond liner, you should try to remove any sharp stones, dead tree roots and any other debris you find in the hole. This could include old bricks, glass or pottery.If your ground soil is quite rocky, you may wish to add a layer of sand to smooth out the surface and create the shape of your pond.
Protective Underlay: Although the hole for your pond may look smooth once you have finished digging, over time changes to the water table and soil movement may bring stones and roots to the surface. To protect against these and give your liner the longest life, we would recommend using a layer of protective underlay or matting to create a barrier between the soil and your liner. In the past, some people have used old carpet or newspaper for this purpose. We would not recommend this because these materials are likely to rot away leaving the liner with no protection. Our aquaSHIELD matting is a geotextile underlay that is rot resistant and will provide long term protection for your liner. Both natural and formal (box welded) ponds benefit from using underlay. Although formal ponds are unlikely to get stones or roots protruding into the liner, often the bricks or concrete used to form the shape has rough surfaces that may wear on the liner.
How and where to use protective underlay
Matting should be laid in the pond prior to placing the liner, to overlay the whole surface area that will be covered by the liner.
In addition, a second layer of matting should be placed over the liner where it will be covered with topsoil, paving, bricks or stones for fixing or edging. This will prevent damage to the top side of the liner.
When ordering protective underlay, you should order 10% more underlay than the pond liner. This allows for overlapping the underlay and any you require for edge detailing.