How to build a pool with composite decking – a complete guide.

Why choose composite decking for building a pool?

Composite decking is a modern material made from a mixture of wood and plastic. It has many advantages:

• Resistant to moisture and mould – unlike wood, it does not crack or rot.
• Safety – the boards have a non-slip surface, helping to prevent accidents.
• Easy maintenance – no painting or treatment required.
• Appearance – available in a range of colours and designs, it blends perfectly with your garden.

Thanks to these properties, composite decking is ideal for both poolside terraces and the pool structure itself.

What materials will you need?

Before you start building, prepare all the necessary materials and tools:

• Composite decking boards – choose a high-quality material that is resistant to the weather.
• Structural joists – aluminium or composite joists are best for greater durability.
• Stainless steel screws and fixings – these help prevent corrosion in a damp environment.
• Pool liner or pre-formed pool shell – depending on the type of pool.
• Water drainage system – important for maintaining good hygiene.
• Tools – drill, spirit level, saw, tape measure and hammer.

Planning and preparing the site.

Before you start building, you need to prepare the site properly.

Choosing a location. 

• Avoid areas with lots of trees to minimise the problem of falling leaves.
• Choose a sunny area – this will allow the water to warm up naturally.
• Make sure the ground is stable and properly compacted.

Excavation and foundations.

If you are building an in-ground pool, dig a hole to the appropriate dimensions. The bottom should be level and reinforced with a gravel or concrete sub-base.

For an above-ground pool, it is enough to level the surface and lay foundation slabs or concrete blocks.

Assembling the pool structure.

Frame and base

Fit the supporting structure, made from joists, onto the prepared ground. They should be evenly spaced to ensure the whole structure is stable.

Important! The joists should be spaced appropriately – usually every 30-40 cm – to prevent the boards from bending.

Fixing the composite decking boards

1. Start at the corners, fitting the first board with special installation clips.
2. Allow for expansion – boards can expand slightly with changes in temperature, so leave a gap of 3-5 mm between them.
3. Check the level – carefully level each board to avoid unevenness.

Installing the filtration system and finishing touches.

A pool needs a suitable filtration system. The most popular options are:

• Sand filter – effective, but the sand needs to be replaced regularly.
• Cartridge filter – easier to use, but less efficient for large pools.

Additional finishing touches:

• Composite decking edging – gives the pool a smart appearance.
• LED lighting – attractive and practical for evening swims.
• Steps or a ladder – for easy access to the water.

Maintaining and caring for a composite decking pool.

A composite decking pool does not require complicated maintenance, but it is worth following a few simple rules:

• Regular cleaning – use a pressure washer or a standard brush with water and a mild detergent.
• Removing algae – use an algaecide if necessary to prevent the surface from becoming slippery.
• Winter protection – if the pool is not used all year round, it is worth covering it with a special tarpaulin.