When a Deck Fails, It's Usually What's Underneath That Matters

A beautiful timber deck should provide decades of enjoyment, not become a costly replacement after just one year.

That was the reality for a homeowner in Franschhoek whose existing pool deck had already begun to fail only twelve months after installation. While the decking itself showed signs of deterioration, the real problem wasn't the timber on the surface, it's what's hidden beneath it.

The original installation overlooked one of the most important principles of decking construction: proper moisture management and structural design.

Fortunately, experienced installer Eddy Serfontein from African Reed, together with the technical guidance and premium materials supplied by Somerset Timbers, transformed the area into a deck designed to perform for many years to come.

Understanding Why the Original Deck Failed

Pool decks present unique challenges.

Water from swimmers, rainfall, irrigation systems, and morning dew constantly introduce moisture into the structure. If that moisture cannot drain away or the supporting structure has not been designed to withstand those conditions, problems develop surprisingly quickly.

In this particular project, several critical issues contributed to the failure of the original deck:

• Poor ventilation beneath the deck prevented the area from drying properly.
• Water splashing from the swimming pool collected beneath the structure.
• Nearby irrigation sprinklers kept the surrounding ground consistently damp.
• The supporting substructure had been installed directly into the ground without the appropriate treatment level for permanent moisture exposure.
• The structural timber was likely treated to H2 or H3 standards rather than the H4 treatment required for ground contact.

These conditions created the perfect environment for fungal growth, mold, timber decay, and premature structural failure.

The lesson is simple: even the highest-quality decking timber cannot compensate for poor substructure design.

Designing the Deck the Right Way

With more than 15 years of experience working alongside Somerset Timbers, African Reed approached the replacement deck very differently.

Rather than simply replacing the boards, the entire supporting structure was redesigned from the ground up.

Structural support poles were installed into concrete footings, creating a stable foundation while allowing water to drain away from the poles instead of remaining trapped around them. The poles were spaced at approximately one-metre intervals to provide excellent structural support across the deck.

The bearer beams and joists were then installed according to Somerset Timbers' recommended spacing guidelines, ensuring the finished deck would perform exactly as intended.

One additional improvement made specifically for this project was the selection of 50×152mm structural joists.

While this exceeded the minimum structural requirement, the increased depth dramatically improved the rigidity of the deck, eliminating the "springy" or "bouncy" feeling often experienced on poorly designed timber decks.

This attention to detail is what separates a deck that simply looks good from one that performs exceptionally well for years.

Choosing the Right Decking Timber

Selecting the right decking species is just as important as designing the correct structure.

For this project, African Reed and the homeowner selected Somerset Timbers' 19×140mm Garapa decking, one of the most popular hardwood decking species in South Africa.

Garapa is highly regarded for its:

• Excellent natural resistance to fungal attack
• Outstanding durability in exterior environments
• High resistance to rot and decay
• Beautiful golden appearance that naturally matures over time
• Long service life with correct installation and maintenance

To minimise joins and create a visually balanced finish, a combination of 2.44m, 3.05m, and 3.96m Garapa decking lengths was used throughout the installation.

The decking boards were secured using Endura A4 Stainless Steel Deck Screws, providing superior corrosion resistance for a demanding outdoor environment.

The Result

Today, the Franschhoek homeowner enjoys a premium outdoor entertaining space built with confidence.

More importantly, they have peace of mind knowing the new deck has been designed with proper drainage, structural integrity, and long-term durability in mind.

Projects like this demonstrate that successful timber construction is about far more than choosing quality products, it requires experience, technical knowledge, and careful planning.

A Partnership Built on Quality

African Reed has partnered with Somerset Timbers for more than 15 years, completing high-quality timber projects across the Western Cape.

According to Eddy Serfontein, the partnership is built on more than just quality timber.

He values Somerset Timbers' knowledgeable and approachable team, reliable product availability, competitive pricing, and the ability to check live stock availability online before planning projects.

These advantages allow installers to quote confidently, plan efficiently, and keep projects moving without unnecessary delays.

Planning a Timber Deck? Start with the Right Advice

Whether you're replacing an existing deck or building a new outdoor living space, long-term performance begins long before the first board is installed.

Choosing the correct structural timber, treatment level, decking species, fixings, and installation method all play a critical role in the lifespan of your investment.

At Somerset Timbers, we work closely with homeowners, architects, builders, and experienced installers to ensure every project starts with the right materials and the right advice.

If you're planning a timber deck, pergola, or outdoor project, visit our showroom or contact our team to discuss the best timber solution for your application.