Hybrid Flooring Is Not Waterproof

Hybrid Flooring: Not Waterproof – What You Need to Know

When it comes to choosing flooring for your home or business, hybrid flooring has gained popularity for its durability, aesthetic appeal, and versatility. However, recent independent testing conducted by the Australian Timber Flooring Association (ATFA) in collaboration with Griffith University and leading importers has shed light on some critical considerations– particularly the fact that hybrid flooring is not waterproof. In this blog, we’ll dive into the findings from this research, explore why moisture management is essential, and explain why partnering with flooring experts like The Flooring Centre and ATFA members is a smart move.

Hybrid Flooring and Moisture: The Testing Takeaways

The ATFA’s comprehensive study, testing 22 hybrid products from seven leading importers in Australia and New Zealand, revealed some reassuring news – and some areas of concern. On the positive side, all tested products were free of harmful substances like crystalline silica, asbestos, and heavy metals, ensuring safety for installers and homeowners alike. The materials also showed minimal volatile organic compound (VOC) emissions, suggesting low risk in that department.

However, when it comes to moisture resistance, the picture isn’t as clear-cut. While hybrid flooring didn’t absorb high levels of moisture overall, the testing highlighted unresolved questions about permeability. Some boards had a “loose” structure, exposing stone fillers to moisture. This exposure can lead to a process called alkalinity hydrolysis (AH), where moisture with high alkaline content – often from new concrete slabs –penetrates the board, breaking down stone elements. The result? Loss of rigidity, cupping of boards, and potential long-term damage. Products with larger, less encapsulated stone particles were especially vulnerable to AH-related issues.

The takeaway? Hybrid flooring isn’t waterproof. It can resist moisture to an extent, but it’s not immune to damage from excessive exposure. This is a critical distinction for anyone considering hybrid flooring in moisture-prone areas like kitchens, bathrooms, or basements.

Alkalinity Hydrolysis: A Deeper Look at the Damage

So, what exactly does alkalinity hydrolysis do to hybrid flooring? The damage can be extensive and multifaceted, affecting both the appearance and functionality of your floors. When high-alkaline moisture –typically from a new or improperly cured concrete subfloor – seeps into the board’s core, it chemically reacts with the stone fillers. This reaction weakens the structural integrity of the material, leading to a cascade of problems:

• Loss     of Rigidity and Cupping: As the stone elements break down, the board     loses its ability to maintain a flat, stable shape. This often manifests     as cupping, where the edges of the boards curl upward, creating an     uneven surface. Cupping not only looks unsightly but can also create     tripping hazards and make the floor feel unstable underfoot.
• Cracking     and Delamination: The weakening caused by AH can extend beyond the     core, putting stress on the board’s outer layers. Over time, this may lead     to cracking of the surface or delamination, where the top layer separates     from the core. Once this happens, the flooring’s aesthetic appeal and     protective qualities are compromised, exposing it to further damage.
• Joint     Failure: Hybrid flooring relies on interlocking joints to hold the     planks together. When alkalinity hydrolysis undermines the board’s     structure, these joints can become stressed or misaligned, leading to     gaps, buckling, or even complete failure. This is especially problematic     in larger installations where movement is more pronounced.
• Long-Term     Deterioration: The damage doesn’t stop at the initial reaction. As     moisture continues to penetrate, the degradation process accelerates,     turning a small issue into a widespread problem. Boards that start with     minor cupping can eventually warp entirely, requiring partial or full     replacement – a costly and disruptive fix.

The ATFA testing noted that boards with larger stone particles, poorly encapsulated by polymers or resins, were particularly susceptible. In these cases, the “loose” core structure allows moisture to travel more easily through voids, bypassing protective barriers and amplifying the effects of AH. This underscores why hybrid flooring isn’t a fool proof solution in high-moisture environments without proper precautions.

The Hidden Risks: Mould and Mildew

Beyond structural damage, excessive moisture in hybrid flooring – especially when exacerbated by alkalinity hydrolysis – can create another headache: mould and mildew. When moisture seeps into the core of the boards, particularly in those with fragmented or porous structures, it creates a damp environment where mould and mildew can thrive. These fungi not only pose health risks, such as respiratory issues and allergies, but they can also cause unpleasant odours and further degrade the flooring over time. The chemical breakdown from AH can worsen this by creating micro-cracks or pockets where moisture lingers, making it harder to dry out affected areas. Left unchecked, what starts as a small moisture problem could turn into a costly repair job.

This is why proper installation and subfloor preparation are non-negotiable. The ATFA testing reinforced industry recommendations to install a minimum 150um thick polyethylene film (builders’ plastic) over subfloors. This layer acts as a barrier, reducing moisture transfer and resisting alkalinity – a key step in preventing AH and the conditions that lead to mould growth.

Expansion, Contraction, and Installation Challenges

Excessive sunlight is a contributor to issues with Hybrid flooring and installs that are in areas facing north and west can be troublesome., as the floor heats up and expands whereas areas not exposed to the direct sunlight do not, causing pressure to build in the floor, potentially causing issues.

The testing also explored how hybrid flooring behaves under temperature changes, offering valuable guidance for installers. Most hybrid products showed consistent expansion and contraction properties – about 0.5mmper meter per 10°C temperature shift. For a typical 25°C temperature range(think 5-10°C in winter to 30-35°C in summer), that translates to roughly1.25mm of movement per meter. In a 12-meter span, you’re looking at up to 15mmof total movement.

This might not sound like much, but it’s enough to cause buckling, joint damage, or gaps if not properly managed – especially if AH has already weakened the boards.

The weight of hybrid flooring adds another layer of complexity – it’s less likely to slide smoothly across a subfloor compared to lighter options, increasing pressure on joints. The ATFA recommends a maximum room size of 12m x 12m (although some suppliers have larger raft sizes) and the use of compartmentalisation trims in complex layouts to mitigate these risks. However, getting this right requires precision and expertise.

Why You Need Flooring Experts

Here’s where working with professionals like The Flooring Centre and ATFA members makes all the difference. Hybrid flooring may be marketed as a low-maintenance, durable option, but as the testing shows, it’s not a “set it and forget it” solution – especially when moisture and alkalinity hydrolysis are involved. Experts understand the nuances of subfloor preparation, moisture barriers, and expansion allowances. They can assess your specific site conditions – like the alkalinity of your concrete slab or the temperature range in your region – and tailor the installation to prevent issues down the line.

Without this expertise, you risk costly mistakes: boards that cup, crack, or delaminate from alkalinity hydrolysis, mould creeping in from unchecked moisture, or joints failing under thermal stress. Flooring specialists bring the knowledge and experience to ensure your investment stands the test of time.

Final Thoughts

Hybrid flooring offers plenty of benefits, but it’s not waterproof – and that’s a fact worth remembering. The ATFA’s testing with Griffith University has given us empirical evidence to better understand its strengths and limitations, from moisture permeability and alkalinity hydrolysis to thermal movement. While it’s a safe and stable option when installed correctly, it demands careful planning to avoid pitfalls like structural breakdown, mould, and mildew.

For peace of mind, trust the experts and consult with the team at The Flooring Centre before you buy your next floor.

Credit: Phil Buckley and the Australian Timber Flooring Association (ATFA) for their research and input into the article in the edition of Timber Floors magazine Issue 58 2025 that formed a large part of this blog post.

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