POLES, DECKING & DESIGN: JNA AT THE WOODAPP WORKSHOP 2025

 

In April, our Technical Director, Abrie Visagie, took to the stage as a keynote speaker at the WoodApp Workshop held in George, South Africa. The focus of the workshop was pole construction and deck building — two areas that reflect our decades of experience and innovation within timber design.

 

Abrie’s talk focused on the work of JNA Group’s Timber Division, one of the four key divisions within the JNA Group. While many in the industry know us from our origins as Lucas Quality Thatchers, the company has evolved over the years into a comprehensive construction group offering specialised services across: JNA Projects - high-end residential construction, JNA Thatchers - carrying forward 30+ years of thatching expertise, JNA Roofing - dedicated to the design and construction of complex roof structures, JNA Timber - specialising in crafting intricate and exceptional timber structures that embody a blend of artistry and engineering precision

 

With over 32 years of experience, Abrie led this workshop, and it served as the perfect platform to share his insights into pole design and construction – a specialty within JNA Group’s Timber Division, that focused on more technical and intricate carpentry work.

 

POLE CONSTRUCTION: INSIGHTS & CONSIDERATIONS

Abrie explored the characteristics and advantages of the poles we commonly use

• CCA Pine Tapered Poles

  • These poles are CCA (Copper Chrome Arsenate) treated to ensure long-term durability. Locally available and environmentally harvested, they form the backbone of many of our projects. We prefer tapered poles over cylindrical ones because the turning process used to make poles perfectly round often removes dense outer layers, weakening the structural integrity. Tapered poles retain more of their natural strength and character, making them both a practical and aesthetic choice.

• Clear Treated SA Pine Tapered Poles

  • About 30 years ago, Abrie collaborated with local sawmills to develop this alternative to the standard green-hued CCA poles. These poles are treated with BORON instead of CCA, keeping the natural timber tone while still offering protection against pests and fungi. The clear treatment gives a more natural, softer finish that blends well with design-focused structures. Boron treatment is also more environmentally friendly, making this option ideal for eco-conscious projects.  

• Clear Treated Poplar Poles

  • Poplar is a timber we’ve come to appreciate for both its structural and aesthetic value. The clear BORON treatment preserves its natural white appearance, giving it a clean, Scandinavian feel with a hint of rustic charm. What makes Poplar truly unique is its internal grain pattern — unlike typical trees, its core doesn't grow in a single axis but intertwines with the sapwood, creating a blend of soft and hardwood textures. It’s a non-indigenous species commonly found in ravines and kloofs across the Eastern Cape and Southern Free State, allowing us to harvest an invasive species in a sustainable way.

• CCA Blue Gum Poles

  • Blue Gum is another sustainably harvested species, known for its strength and availability. These poles are CCA treated for durability, and their structural properties surpass SA Pine — especially in terms of modulus of elasticity. Because of this, Blue Gum poles are typically used where long spans and heavy loads are involved, providing us with the strength and flexibility needed for more demanding construction challenges.

 

A few key considerations when working with poles:

• Structural Integrity: Drilled connections can cause cracks, especially near the ends. Always pre-drill and avoid placing bolts too close to edges. Using washers and tightening bolts gradually also helps distribute stress.

• Moisture Content: Moisture plays a huge role in both stability and durability. Poles should be properly installed and stored to prevent warping, splitting, and fungal growth.

• Fire Performance: Poles generally have a low charring rate and can maintain load-bearing capacity better than both steel (which softens) and sawn timber in a fire scenario. Taper and Shape Variation: Each pole is unique – taper, curvature, and diameter can vary. This requires careful selection and layout during construction, especially for symmetry.

• Treatment Penetration: Especially with BORON & CCA, ensure the preservative has penetrated sufficiently – core sampling or working with trusted suppliers is key to quality assurance.

 

NOTABLE CASE STUDIE WE EXPLORED

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Lapalala

Lapalala is a remote conservation reserve located in the heart of the Waterberg Biosphere in Limpopo. This was a dome pole structure – every pole was manufactured in our workshop and measured to the perfect size. The dome was assembled 1800 km from our main office in Limpopo province, all poles were connected with metal cleats. Precise planning and the easy workability of poles allowed us to deliver efficiently. The structure was built using clear treated SA Pine poles.

 

Rooi Duin

Rooi Duin is situated deep in the Kalahari, a landscape that demanded sensitivity to the natural surroundings and harsh climate. Rooi Duin was a unique project; the clear treated SA Pine pole lodge was constructed to mimic sociable weaver nests, with a central pole supporting the entire structure. The versatility of poles was showcased during this job, both structurally and aesthetically.

 

Kwandwe Family House

Kwandwe, a private game reserve in the Eastern Cape, required a modern structure that complemented the surrounding bushveld without compromising on traditional aesthetics. To achieve this, a pole structure was cleverly suspended from a portal steel frame, eliminating the need for interior tie-beams and creating the illusion of a traditional thatch roof from both inside and out – striking a perfect balance between open-plan design and authentic, natural charm.

 

Tankwa

For the Tankwa Farm House the aim was to restore the original homestead feel while upgrading structural integrity and comfort. Reconstructed using poplar poles to retain the heritage aesthetic while adding a modern twist. The structure was both built and designed to maintain authenticity and functionality.

 

De Mond

De Mond is a coastal heritage site known for its protected estuary and historic cottages. This project required sensitivity to traditional Cape-style architecture and the coastal environment. De Mond was another heritage example where a typical traditional structure was constructed using clear treated SA Pine poles, combined with poplar poles for the ceiling beams. It seamlessly showcases a classy finish while preserving cultural heritage.

 

Some of our most notable projects include Lapalala in the Waterberg Biosphere, where a dome structure made from pre-measured SA Pine poles was assembled 1800 km from our base with precision and ease. In the Kalahari, Rooi Duin showcased the versatility of poles with a lodge design inspired by sociable weaver nests, centred around a single structural pole. Truly a unique project. At Kwandwe Family House in the Eastern Cape, we created a modern open-plan space by suspending the pole structure from a steel frame - achieving the look of a traditional thatch roof without interior tie-beams. For Tankwa Farm House, we used poplar poles to restore a heritage homestead with a functional yet authentic feel. Lastly, De Mond, a coastal heritage site, combined SA Pine and poplar poles to deliver a refined Cape-style finish while preserving the site’s historic character.

 

DECK CONSTRUCTION: PRACTICAL LESSONS FROM THE FIELD

In addition to pole work, Abrie shared JNA's approach to deck construction - combining engineering know-how with a keen understanding of client expectations.

 

Support Structure

• Frame: Sawn CCA-treated SA Pine supported by CCA H3-treated poles 

• Design Approach: Exceeds code minimums for enhanced stability 

• Feel: Our clients prefer the solidity and strength of a well-built deck 

• Joist Spacing: ≤ 450mm with stiffeners every 1.2m (ideally 152x50mm joists) 

• Protection: Bitumen applied to joist tops to prevent water ingress at fixings 

 

DECKING MATERIAL WE'VE USED

Our decking portfolio features a wide range of premium materials, including Balau, Massaranduba, Garapa, Jatoba, Teak, Thermo-treated Pine, CCA H3-treated SA Pine, Gum, MOSO Bamboo, and Composite Decking.

 

At JNA Group, we’re proud to be pushing boundaries in timber construction – drawing from traditional skills while integrating modern technologies and techniques. Whether we’re working with poles in the Karoo or building bespoke decks along the Garden Route, we remain committed to quality, structural integrity, and client satisfaction.

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