Pond Construction Materials
A variety of pond construction materials are available,
the most common of which are concrete and
flexible EPDM liner.
Each has their own strengths and weaknesses as follows:
Concrete, either
pure concrete or mortared building blocks or rock, was until recently the
most commonly used pond building material. Most formal ponds are still
made from tiled concrete or mortared rock. Concrete ponds are the least
expensive in materials cost to construct, but will require extra care over
time. Because concrete is porous by nature, it will allow water intrusion
into its structure, and hence is subject to damage by freezing and general
breakdown in soil. This can be prevented by application of a penetrating
structural sealant every few years. However, its lack of flexibility also
makes it susceptible to cracking under pressure from growing tree roots
or shifting of unstable substrates.
Flexible liner materials
such as EPDM
(ethylene propylene diene monomer) and PVC (polyvinyl
chloride) are relatively expensive to purchase, but allow tremendous flexibility
in pond design while providing excellent durability. EPDM has the higher
elasticity and UV resistance of the two, while PVC has a
slightly tougher surface. A heavy weight 45 mil EPDM should provide 30+
years of trouble-free pond life when installed over a soft underlay or
layer of sand (lighter weights of EPDM are not recommended, although PVC
is commonly sold in 25 and 30 mil weights). Flexible liners are subject
to puncture damage by knives, claws or other sharp objects, but are relatively
easy to patch. Where a mortared rock effect is desired, an EPDM liner can
be installed under the mortar to prevent the need for sealants.
Preform plastic shells are
a quick and easy alternative to constructing a pond from scratch. Now available
in a reasonable variety of shapes and sizes, preforms offer great durability
(although thickness and quality vary widely) at the expense of the ability
to create a custom shape or make design changes during construction. Good
quality preforms are also expensive to purchase but don't require the prep
work and extra materials needed for EPDM.
