Structure & Site
Excavation Estimating Services in New Zealand
Detailed excavation quantities for footings, basements, trenches and pits, with backfill, disposal and support measured separately.
Where earthworks deal with the shape of the whole site, excavation is about the holes: footing trenches, pile holes, basement digs, service trenches, manholes and pits. Each comes with its own working space, its own spoil, and its own backfill requirements.
We measure excavation to the depths and widths shown, plus the working space and battering or support required to dig safely. Spoil is separated into material for reuse and material for disposal, and backfill is measured by type, so you can price imported granular material separately from returned spoil.
On deep basements and tight urban sites, we also measure shoring, dewatering allowances and any rock excavation indicated by the geotech.
Scope
What we measure in a excavation takeoff
| Item | Unit | What it covers |
|---|---|---|
| Footing excavation | m³ | Strip and pad footings to the depths shown, plus working space. |
| Basement excavation | m³ | Bulk dig with battering or support assumptions stated. |
| Service trenches | lm / m³ | By depth band and width, per service type. |
| Pits and manholes | no. / m³ | Excavation for chambers, sumps and tanks. |
| Backfill | m³ | Returned spoil versus imported granular backfill. |
| Disposal | m³ (loose) | Surplus spoil with a bulking factor applied. |
| Support and dewatering | m² / item | Shoring, trench boxes and pumping allowances. |
| Rock excavation | m³ | Provisional quantities where the geotech indicates rock. |
Deliverables
What you receive
Excavation takeoffs show quantities in depth bands, because the cost of digging and supporting trenches rises with depth.
| Itemised quantity sheet | Excel + PDF |
| Marked-up plans | Colour-coded PDF |
| Material and labour schedule | Excel |
| Assumptions and exclusions list |
Who it is for
Built for the people who price the work
- Builders
- Price foundations on a sloping section with excavation, disposal and backfill all counted.
- Subcontractors
- Drainlayers and civil contractors can price trenching by depth band.
- Developers
- Understand the cost of adding a basement before committing to the design.
- Architects
- See the excavation and retention effect of setting a building lower on its site.
Process
How a excavation estimate runs
STEP 01
Upload plans
Upload the foundation plan, services drawings, survey and geotech report.
STEP 02
Scope confirmation
We confirm working space, batter angles or support methods, and disposal assumptions.
STEP 03
Takeoff and review
Excavation is measured by element and depth band, then reconciled with backfill and disposal.
STEP 04
Delivery
You receive the quantity sheet, depth-band summary, PDF and marked-up plans.
New Zealand context
Standards and practice
WorkSafe New Zealand guidance on excavation safety sets expectations for trench support and safe working near excavations. Where trench depths exceed what can be dug safely without support, we include support allowances rather than leave them out.
Before any digging, underground services need to be located; beforeUdig is the national service for requesting plans from utility owners. Where existing services are close to the works, we note potential hand-digging allowances.
We measure and price to the drawings. Design compliance and building consent remain with your designer and building consent authority.
Cost drivers
What drives the cost of excavation work
01
Depth
Deeper excavations need more support, more working space and slower digging. Depth is one of the biggest drivers of excavation cost, which is why we report trenches in depth bands.
02
Groundwater
Excavations below the water table need pumping or dewatering and may need different backfill. The geotech report usually tells us where to expect it.
03
Spoil handling
Spoil that can be reused on site costs much less than spoil that must be carted away, especially if it is contaminated or unsuitable.
04
Existing services
Digging near live services slows work and may require hand excavation or vacuum excavation. We note these risks where drawings show services nearby.
Where excavation estimates go wrong
Excavation is commonly underestimated by measuring only the volume of the footing or pipe trench, without working space, batters or over-excavation. The real dig is larger than the finished element.
Backfill is the other weak point. Imported granular backfill around pipes and behind walls can cost more than the excavation itself, and returned spoil may not be suitable. We measure backfill by type so the difference is visible.
Hand digging near services is also easily missed. Near live services, machines must stop and hand digging takes over.
FAQ
Excavation Estimating questions
Do you include working space in excavation volumes?
Yes. We add working space as stated in our assumptions, which you can change to suit your method.
How do you treat contaminated soil?
Where a site investigation identifies contamination, we separate the affected volume so specialist disposal can be priced.
Can you measure trenches by depth?
Yes. Trenches are reported in depth bands so pricing reflects the extra effort and support needed at depth.
Do you include shoring design?
No. We measure areas and allowances for shoring, but the design is by a specialist engineer.
Do you allow for rock?
Only where the geotech report indicates it. Rock is shown as a provisional quantity because its extent is uncertain until you dig.
Related services
- Earthwork Estimating
Cut and fill volumes, topsoil strip and engineered fill quantities, calculated from your existing and design levels.
- Concrete Estimating
Concrete volumes in m³, formwork in m² and reinforcing in tonnes, measured element by element from your structural drawings.
- Plumbing Estimating
Plumbing and drainage quantities from fixture counts to pipe runs, with hot water systems, valves and fittings measured.
- Sitework Estimating
Civil and site infrastructure quantities: drainage, water, roads, kerbs, retaining and paving, measured from your civil drawings.
Get a quote
Send your plans for a excavation estimate
Upload your drawings and we will reply with a fixed fee and turnaround before any work starts. No obligation.
- — PDF, DWG and ZIP accepted
- — Fees in NZD, excluding GST
- — Prefer email? Use the link in the footer