Building a wooden deck or pontoon over a pond: structure, liner, and pitfalls to avoid

A wooden deck extending a few dozen centimeters over the water completely changes the perception of a pond: you sit above the fish, the bank disappears, and the cast shadow cools the water. Of course, the structure must not threaten the waterproofing.

Rule no. 1: the deck never rests on the liner

The structure rests on its own foundations, outside the pond whenever possible. The part over the water is cantilevered from the bank. For a large overhang, blocks can be placed in the pond, but only on a support prepared before installing the liner (slab or base), with reinforced protection: thick felt and an additional piece of liner under each support.

The right wood and the right hardware

• Structure made of wood treated for contact with the ground and moisture, or naturally durable wood, or composite.
• Screws and brackets in stainless steel: galvanized steel rusts quickly above water.
• Avoid freshly treated wood that could drip into the pond.
• Leave a gap under the boards for ventilation: the wood dries, lasts longer.

Think technical from the start

• A hatch above the skimmer, pump, or cable passages.
• An overhang of at least a few centimeters above the water to hide the liner: see how to hide the liner.
• Conduits provided under the deck for lighting and pumps.

Shade and fish

Fish love taking refuge under a pontoon: it is a shelter against the sun and against the heron. Shade also helps limit the temperature rise in summer. However, keep a good part of the pond sunny for the plants.

Safety

A pond under a deck remains a body of water: handrails, cover, or safety grille if young children frequent the garden. Wet boards are slippery: prefer grooved or non-slip boards.

A project for a deck over water? The Foudebassin team answers you: contact us, or come see our landscaping in our aquatic garden center.