A guide to lining your pond with pond liner underlay
Having dug out your pond excavation and smoothed the surface down as much as possible to protect the pond liner it is time to introduce the pond liner underlay. If you wish you may line the pond with sand as well – this is especially useful if the base of the pond has large deviations (eg, brick edges poking through the surface making it uneven).
The pond liner underlay you receive will almost certainly be supplied to you in strips. This is because the fabric tends to be manufactured onto large rolls of fixed diameter that are then cut down. If you think about it this makes sense, the pond liner underlay does not have to be watertight (unlike the pond liner) so it makes it easier to produce, transport, store and lay in smaller pieces. The pond liner underlay we sell is supplied in pieces of 2x5m, 2x6m and 2x8m.
As a general rule of thumb the most suitable amount of pond liner underlay to purchase is to match the pond liner size itself. Sometimes use of pond liner underlay isn’t as critical – eg, on the sides of the pond excavation, as this area doesn’t face as much weight so if smooth it might be okay to leave bare. However, remember that you might have rougher areas where the pond liner underlay needs to be laid two, three, four or more pieces deep. In our experience matching the pond liner size works in most cases.
When laying down the pond liner underlay make sure it overlaps by 3-4 inches (7-10cm) so not to risk areas being left exposed. Our pond fleece underlay tends to naturally grip the surface it is placed onto but overlaps can be kept in place using tape to ensure they don’t move out of position when the pond liner is laid. Ensure the complete excavation is covered – even the perimeter as heavy stones may be laid on the edge. Don’t bother cutting off any excess until the pond liner itself has been laid and filled with water. Standard scissors should be enough to cut through most pond liners. For a pictorial example of a pond liner underlay being laid please visit our new pond build diary article.