Does Water Go Through Composite Decking?

Composite decking is a popular choice for construction professionals for its durability, versatility, low maintenance requirements, and aesthetic appeal. However, when it comes to ascertaining whether or not it is waterproof, there is some confusion. In this article, we provide a comprehensive guide to composite decking’s water resistance and how you can expect composite materials to react in wet conditions.

Understanding composite decking

To understand composite decking’s water-resistant qualities, it is important to look at its composition and construction and how these factors affect its performance. Composite decking is made from a combination of wood fibres, recycled plastics, and bonding agents. This mixture is processed and pressed into boards that resemble traditional wooden decking.

Compared with wooden boards, composite boards typically offer greater longevity and superior resistance to rot, insects, and warping. However, though composite decking is highly resistant to moisture-related issues, it is not entirely waterproof.

Looking at composite decking’s structure

Premium quality composite boards have a protective outer layer, commonly referred to as a cap. This cap is usually made from plastic and resin and provides a durable and moisture-resistant shield. It helps to prevent water from seeping into the board’s core and protects it from stains, fading and mould growth.

However, the cap is not entirely impervious to water and may still be susceptible to moisture absorption over time. The quality of the cap can affect how water resistant the board is, so it pays to source your materials from a trusted, reputable, high-quality supplier.

Is composite decking waterproof?

In short, composite decking is not entirely waterproof. But it is much more water-resistant than traditional timber decking. While composite boards are designed to resist moisture, they are not immune to the effects of prolonged exposure to water or extreme weather conditions.

For instance, if water is allowed to pool on the surface of the decking for extended periods, it may seep into the board via cracks or scratches. However, even when this occurs, composite boards will last much longer than timber boards exposed to the same conditions.

Improving composite decking water resistance

Proper installation and maintenance are crucial to ensure optimal water resistance and extend the lifespan of your composite decking. Regular cleaning and inspection will also help identify and address any potential issues before they become significant problems.

The overall quality of the composite decking plays a considerable role in the degree of water resistance you can expect. Higher-quality composite boards often feature advanced manufacturing techniques and offer superior water resistance. This often justifies investing more in high-performance materials from an established and well-respected brand.

Waterproofing under composite decking

While much is made of how water-resistant decking boards are, other components in the decking structure are just as important. Exposed decking joists can suffer from water damage, so make sure you select aluminium decking joists for your substructure. Timber decking joists for example can suffer from water damage, and begin to sag and warp, leading to distortion and damage to the decking surface above. This situation can leave you with a dangerous substructure and a costly remediation and repair project.

RYNO composite decking boards and systems

Though composite decking is not entirely waterproof, it offers a high level of resistance to moisture-related problems compared to traditional wood decking. Its solid construction, protective cap, and inherent resistance to rot and warping make it the preferred choice for decking solutions.

At RYNO, we stock a wide range of composite boards well-suited to varied construction projects. Whether you are completing remediation work on external balconies or designing outdoor areas for new builds, our high-performance composite boards are an excellent choice. They can also be integrated into our innovative TerraSmart® Composite Decking System for a beautiful deck that benefits from an appealing aesthetic, remarkable longevity and a 10-year full system warranty.

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