When planning a driveway in Auckland, the material beneath the surface matters more than most people realise. With regular rainfall, mixed soil types, and daily vehicle use, the long-term performance of a driveway depends heavily on the base layer.
For most residential projects, Gap 20 aggregate is a proven and dependable option for Auckland conditions, provided it is installed correctly and matched to the site.
What Gap 20 aggregate is and how it works under a driveway
Gap 20 aggregate is a 20mm gap-graded crushed stone used for structural base layers.
It compacts tightly while still allowing water to move through the base, which helps prevent moisture-related failure. This balance is why Gap 20 Aggregates Auckland is widely used beneath concrete, pavers, and other driveway finishes.
Rather than sitting on soft ground, the driveway surface is supported by a stable, well-draining foundation.
Why Auckland soil and climate affect driveway performance
Auckland soils often contain clay, which expands when wet and contracts when dry. Without a suitable base, this movement transfers directly to the driveway surface.
Over time, this can lead to:
- Cracking
- Uneven levels
- Depressions where water collects
Gap 20 helps reduce these issues by distributing loads evenly and limiting water retention within the base.
How Gap 20 performs in wet conditions
Water management is one of the main reasons Gap 20 performs well in Auckland.
Its gap-graded structure allows rainfall to pass through the base instead of becoming trapped. This reduces saturation and helps maintain compaction, even during prolonged wet periods.
From practical experience supplying aggregates for Auckland projects, drainage performance is one of the biggest contributors to driveway longevity.
Comparing Gap 20 with other commonly used aggregates
Is gap 7 suitable for a driveway base?
gap 7 is typically too fine to be used as a primary driveway base.
While it compacts very tightly, it does not offer the same structural support or drainage as Gap 20. It is more commonly used as a bedding layer or for light pedestrian areas, such as pathways and patios, where a smoother finish is required. This is where gap 7 is more appropriate.
When would gap 40 be a better choice?
gap 40 is a much coarser aggregate designed for deeper structural builds.
It is often used where heavy vehicles are involved or where additional drainage is needed beneath large structures. For most residential driveways, however, it is unnecessary and can complicate finishing layers. In those heavier-duty situations, gap 40 is typically specified instead.
How thick should Gap 20 be for an Auckland driveway?
A compacted depth of 100 to 150mm suits most residential driveways in Auckland.
The final depth depends on:
- Vehicle weight and frequency
- Ground conditions
- Drainage requirements
Installing and compacting the material in layers is essential to achieve long-term stability.
Using Gap 20 beneath concrete, pavers, and retaining structures
Gap 20 is commonly used beneath concrete driveways and paving systems because it provides a firm, even base that limits movement.
Where driveways interact with retaining walls, base preparation and drainage become even more important. In these situations, systems such as firth retaining wall products are often used alongside a well-compacted aggregate base to manage soil pressure and water flow.
Installation issues that shorten driveway lifespan
Even a high-quality aggregate can underperform if installation is rushed or incomplete. Common problems include:
- Insufficient excavation
- Inadequate compaction
- Using too thin a base layer
- Failing to plan drainage paths
Most driveway failures traced back to these issues rather than the aggregate itself.
Why local experience matters when choosing aggregates
Aggregates behave differently depending on soil type, weather patterns, and usage. Suppliers who work extensively with Auckland projects understand how materials perform across different suburbs and site conditions.
Citi Landscape Supplies has supplied aggregates, retaining solutions, and landscaping materials across Auckland for many years. That experience informs practical guidance on material selection, helping ensure the base you choose suits both the site and the intended use.
This local, experience-based knowledge is a key reason why driveway bases perform better when materials are chosen with regional conditions in mind.
Is Gap 20 the right choice for your driveway?
For most residential driveways in Auckland, Gap 20 aggregate remains a reliable and well-balanced base material. It offers the strength needed for vehicle traffic while handling moisture effectively in wet conditions.
When sourced locally and installed correctly, it supports a driveway that stays level, drains well, and lasts for years without major issues.
FAQ
Is Gap 20 aggregate good for residential driveways?
Yes. It provides strong load support and effective drainage.
Can Gap 20 be used as the finished surface?
No. It is designed as a base layer beneath concrete, pavers, or chip seal.
Does Gap 20 work in clay soil?
Yes, particularly when combined with correct compaction and drainage.
How long does a Gap 20 driveway base last?
When installed properly, it can last for decades.
Is Gap 20 better than AP20 in wet areas?
Gap 20 generally drains better, making it more suitable for Auckland’s wet conditions.
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