Foundation Excavation & Preparation | Nelson & Tasman

Every successful build starts below ground. Whether you're constructing a family home, commercial building, or industrial facility, proper foundation preparation is non-negotiable. We work with builders, developers, and property owners to ensure your project starts on solid ground.

Why foundation preparation is critical

Foundation issues don't just threaten your build – they can make it unbuildable. Poor preparation leads to settlement, cracking, water ingress, and structural failure. In contrast, properly prepared foundations provide stable platforms that support your investment for generations. With building costs where they are, getting the foundation right the first time isn't optional.

Foundation services we provide

Residential foundation preparation

House sites require precision. We excavate to engineer-specified depths, achieve required bearing capacities, and create level building platforms within tolerance (typically +/- 20mm). This includes benching into slopes, dealing with fill requirements, and preparing for both concrete slab and timber pile foundations. We coordinate with geotech engineers when required and ensure all work meets NZS 3604 standards.

Commercial & industrial foundations

Commercial projects demand exact specifications. We handle bulk excavation, achieve specified compaction densities (typically 98% maximum dry density), and prepare for heavy loadings. This includes preparing for reinforced raft slabs, individual pad footings, and strip foundations. We work to engineer's drawings and coordinate with other trades to maintain project timelines.

Engineered fill placement

When sites need building up, proper fill placement is crucial. We source certified hardfill, place in maximum 200mm layers, and compact to specification. Each layer is tested and documented. We install geotextile reinforcement where required and ensure proper benching into existing slopes. All fill placement includes certification for building consent compliance.

Rock breaking & difficult ground

Nelson-Tasman's variable geology means encountering rock. We have excavators equipped with rock breakers for controlled removal. For sensitive sites near existing structures, we use specialised techniques to minimise vibration. Rock excavation is charged separately – we'll assess and quote before proceeding.

Retaining wall foundations

Retaining walls fail from the bottom up. We excavate to required depths (typically minimum 100mm below frost line), prepare level bases, and ensure proper drainage behind walls. For engineered walls, we follow designer specifications exactly – the few hundred saved by cutting corners here costs thousands when walls fail.

Our foundation preparation process

1. Site evaluation & planning

We review geotech reports, engineer's plans, and site constraints. This includes identifying underground services, confirming site boundaries, and establishing levels. For sites without geotech reports, we can arrange testing or work with your preferred engineer. Planning prevents expensive surprises.

2. Precise excavation

Modern GPS-equipped excavators allow millimetre-accurate excavation. We establish site benchmarks, set up level controls, and excavate to exact specifications. Spoil is either stockpiled for reuse or removed immediately – we'll advise the most cost-effective approach for your project.

3. Ground improvement

Not all ground is suitable for building. We provide various improvement methods: removing and replacing unsuitable material, stabilising with hardfill, installing drainage to manage groundwater, or coordinating specialist ground improvement contractors for difficult sites.

4. Compliance & documentation

Building consents require proof of proper foundation preparation. We provide compaction test results, level surveys, fill certification, and photographic documentation. Our work is inspection-ready, avoiding delays in your building programme.

Working with your team

Foundation preparation is rarely standalone – it's part of your larger project. We coordinate with:

• Your builder: Ensuring platforms are ready when needed, maintaining access routes
• Engineers: Following specifications exactly, arranging inspections at hold points
• Service contractors: Protecting existing services, preparing for new installations
• Council inspectors: Having documentation ready, achieving sign-offs promptly

Investment considerations

Foundation preparation typically represents 5-10% of total build cost but prevents 90% of structural problems. Costs vary based on:

• Site accessibility and slope
• Excavation volume and depth
• Ground conditions (rock, groundwater, unsuitable soils)
• Disposal requirements for excavated material
• Compaction and testing requirements
• Engineer specifications and oversight needs

Typical residential foundation preparation: $8,000-$25,000
Commercial projects: Quoted based on engineer's specifications

Common challenges we solve

• Sloping sites requiring extensive cut and fill
• High water tables needing dewatering or drainage
• Rock requiring removal for foundation depth
• Unstable soils needing replacement or stabilisation
• Tight sites with limited access or spoil storage
• Contaminated ground requiring special handling

Ready to build on solid ground?

Whether you're a homeowner planning your dream build, a developer preparing multiple lots, or a commercial builder needing reliable foundation preparation, we deliver the quality groundwork your project deserves.

Discuss your foundation requirements – call 027 KIWIBUILD (027 549 428) or send your plans for accurate pricing.