Can You Put Composite Decking on Wooden Joists?

January 2024
Anton White

When considering the installation of composite decking, a common query is whether it's suitable to place it on wooden joists. So, can you put composite decking on wooden joists?

While this is technically possible, it's not the ideal long-term solution. Composite decking boasts a sleek design and high durability, but pairing it with wooden joists can lead to issues down the line.

Wood, even when pressure-treated, is prone to rot, potentially undermining the longevity of your deck as the durable composite boards outlast their wooden base. But what should you do instead?

Dive into our guide to find out.

What this article covers:

Can You Lay Composite Decking on Wooden Joists?

While it's technically feasible to lay composite decking on wooden joists, our extensive experience suggests a more robust alternative. Composite decking, known for its sleek design and exceptional durability, does pair with wooden joists, but there's a significant caveat to consider.

Wooden joists, even when pressure-treated, are susceptible to rot over time. This natural degradation can undermine the longevity and stability of your decking.

The composite boards, which are one of the best types of garden flooring and are renowned for their resilience, are likely to outlast their wooden foundations, leading to potential structural issues down the line.

composite decking on wood frame

After rigorous testing and evaluation, we've concluded that aluminium, steel, or plastic joists are superior choices for supporting composite decking. These composite decking joists offer enhanced durability and sturdiness, significantly outperforming wood in terms of longevity.

Unlike wood, they don't succumb to rot, ensuring that your decking remains stable and secure for many more years. Opting for these materials means investing in a foundation that matches the lifespan and robustness of your composite decking, creating a harmonious and enduring outdoor space.

Benefits of Steel Joists

Steel joists, offered by Ovaeda, are a powerhouse in the world of decking. Their primary advantage lies in their exceptional strength and durability.

Steel, known for its robustness, can withstand heavy loads and extreme weather conditions, making it an ideal choice for areas with harsh climates or for decks that will bear significant weight. Additionally, steel joists are resistant to warping, twisting, and rotting, unlike their wooden counterparts.

This means they maintain their structural integrity over time, ensuring your composite decking remains level and stable. Furthermore, steel joists are a sustainable choice, often made from recycled materials and being fully recyclable at the end of their long lifespan.

Benefits of Aluminium Joists

Aluminium joists, another excellent product from Ovaeda, bring a unique set of benefits to decking projects. These joists are incredibly lightweight, making them easy to handle and install, which can significantly reduce the labour and time involved in constructing your deck.

Despite their lightness, aluminium joists are remarkably strong and provide ample support for composite decking. They are also impervious to rust and corrosion, making them a perfect choice for coastal areas or environments with high moisture levels.

Aluminium's natural resistance to the elements ensures a long-lasting, maintenance-free foundation for your deck, adding to the overall longevity of your outdoor living space.

can you lay composite decking on wooden joists

Benefits of Plastic Joists

Plastic joists from Ovaeda offer a modern solution to various composite decking types. One of their most significant advantages is their resistance to moisture and rot, making them ideal for environments where wood would quickly deteriorate.

This resistance extends the life of your deck significantly, as the joists will not weaken or decay over time. Plastic joists are also incredibly low maintenance; they do not require the regular treatments or preservatives that wooden joists need.

Additionally, they are often made from recycled materials, making them an environmentally friendly option. Lightweight and easy to work with, plastic joists simplify the installation process, ensuring a quicker and more efficient deck construction.


While laying composite decking on wooden joists is technically doable, aluminium, steel, or plastic is much better. Because they aren't susceptible to rot, they're a lot more durable and will last you much longer than wood.

If you are going to use wood, ensure the joists are pressure-treated and well-constructed, and be sure to follow the steps outlined above.

And if you're looking for premium-quality composite decking boards to go on top of your wooden joists, look no further than the ones offered by Ovaeda.

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