Earthworks are among the most common jobs in construction and landscaping. The mini excavator stands out as the go-to machine: compact, manoeuvrable and powerful, it does in a few hours what would take several days of manual work. Weight class, attachments, techniques, costs: the complete guide to getting your job right.
What are earthworks?
Earthworks cover all the operations that reshape a site's ground level to prepare it for a building or a development. They govern the stability of structures, drainage and the soundness of foundations:
- Stripping: removing the topsoil layer (20 to 30 cm), essential because topsoil is compressible and unstable
- Excavation: removing soil to reach the desired level or to dig foundations, trenches and pools
- Backfilling: adding materials (hardcore, graded aggregate, gravel) to fill or raise the level
- Levelling: grading to the levels on the plan
- Trenching: narrow excavations for pipes, cables, fibre, drains
Why a mini excavator for earthworks?
- Access to tight areas: from 75 cm wide, it gets through any gate
- Precision: proportional hydraulic controls for millimetre-perfect movements
- Versatility: strips, digs, levels and loads simply by changing the bucket
- Easy transport: 800 kg to 2.5 t on a standard trailer
- Productivity: a 1.8 t moves 30 to 50 m³/day, equal to 3 to 5 days of manual work
- Controlled cost: from €4,125 excl. VAT, paying for itself from just 15 days of use a year
Soil types and their impact
The nature of the soil is the single most decisive factor in choosing the right weight class.
Clay soil
The hardest: plastic and sticky when wet, hard as concrete when dry. Go for a mini excavator of at least 2 tonnes (20 hp+), ideally after a few days without rain. Excavation volumes in compact clay are 30 to 40% lower than in loose soil.
Sandy soil
Easy to dig but prone to collapse: shoring or battering back is essential for trenches over 60 cm, even below the 1.30 m legal threshold (France).
Rock and stony ground
Requires a hydraulic breaker and a mini excavator of 2.5 to 4 tonnes to absorb the vibrations (breakers in the 200 to 500 kg class).
Existing fill
Complex (waste, blocks, rebar, voids): an auger survey or a geotechnical engineer's assessment is recommended.
Preparing the site
Soil study: a geotechnical study is recommended, and mandatory for new builds in clay/seismic zones since France's ELAN law of 2018 (G1: €500 to €2,000). Setting out: mark the outlines with pegs and string lines — a 20 cm error has consequences. DICT: in France, this declaration is mandatory before any digging, via reseaux-et-canalisations.ineris.fr — it is free and protects your liability. Access: measure the gate, check the load-bearing capacity of the track, and plan a spoil deposit area (10 m³ of excavation = 13 to 15 m³ of spoil once bulked up).
Types of work and recommended weight class
| Type of earthworks | Weight class | Attachments |
|---|---|---|
| Utility trenches (loose soil) | 800 kg to 1.5 t | Trenching bucket, ditching |
| Compact/clay trenches | 1.5 to 2.5 t | Reinforced bucket, breaker |
| Garden earthworks | 1.5 to 2.5 t | Digging bucket, blade |
| House foundations | 2.5 to 3.5 t | Wide bucket, blade |
| Stripping / utility works | 2.5 to 4 t | Wide ditching bucket, blade |
| Earthworks on a slope | 2 to 3.5 t | Wide tracks |
| Pool (loose soil) | 1.8 to 2.5 t | Bucket, quick hitch |
| Pool (hard ground) | 2.5 to 4 t | Breaker, bucket |
| Rocky ground | 2.5 to 4 t | Breaker essential |
Essential attachments
- Digging bucket: hardened teeth, 200 to 800 mm depending on the weight class
- Ditching bucket: toothless, wide, for levelling and finishing to grade
- Backfill blade: to push, backfill, level
- Quick hitch: bucket change in 30 s, 30 to 40 min saved per day
- Hydraulic breaker: for hard, compacted, rocky ground
The steps to successful earthworks
- Site survey and DICT: utilities, soil analysis, setting out
- Setting out: pegs and string lines
- Preparing access: gate, trackway mats, spoil deposit area
- Stripping: 20 to 30 cm with the ditching bucket, topsoil stored separately
- Digging / excavation: passes of 40 to 50 cm, working from the centre out to the edges
- Cleaning the bottom: ditching bucket, checked with a laser level
- Backfilling and compaction: layers of 20 to 30 cm max, each one compacted
- Final levelling: millimetre adjustment
Earthworks on a slope: safety
Always travel perpendicular to the slope (tracks across it), never along it. Above 15°, reduce the load and set the blade on the ground on the downhill side. For steep slopes (> 20°), create successive horizontal benches in steps. Respect the batter angles: ~45° in dry cohesive ground, 30° in wet sand, < 20° in saturated clay. Prefer models with wide tracks and variable track width (2 to 3.5 t).
Compaction and finishing
Uncompacted ground settles: a slab laid on top of it cracks. Any layer thicker than 20–30 cm must be compacted before the next one. Tools: vibrating plate (accessible surfaces), roller compactor (large areas), hydraulic tamper (narrow trench bottoms). The toothless ditching bucket is the finishing tool par excellence — some add laser guidance for levelling to ±1 cm.
Common mistakes
- Skipping the DICT: the most dangerous and most heavily penalised mistake (France)
- Undersizing the machine: an 800 kg on 200 m² of clay struggles and wears out
- Working with the bucket too full: 70–80% of capacity is more productive and precise
- Forgetting to compact backfill: cracking is inevitable
- Working on a slope without precautions: never sideways without the blade on the ground
- Underestimating spoil volume: bulking of 30 to 50%
- Digging too close to existing foundations: a risk within 2 m of a building
Cost per m³ by ground type
| Ground type | Difficulty | Indicative price / m³ |
|---|---|---|
| Topsoil, loose ground | Easy | €15 to €25 |
| Compact clay soil | Medium | €25 to €45 |
| Stony / gravel ground | Medium | €30 to €50 |
| Soft rock (limestone) | Hard | €50 to €100 |
| Hard rock (granite, sandstone) | Very hard | €100 to €200 and up |
| Heterogeneous fill | Variable | €40 to €80 |
Excluding tipping fees (€5 to €20/m³ depending on distance). By doing the earthworks yourself, costs come down to fuel (€3 to €6/h) and depreciation. On a 50 m³ job, the saving can exceed €1,000 to €2,000.
An earthworks project?
Our experts point you to the right weight class and the attachment pack suited to your ground.
Hire a professional or do it yourself?
Call in a pro: rocky ground, excavations > 2 m, densely built-up areas, large jobs (> 200 m³). Do it yourself: garden earthworks, trenches in loose ground, several upcoming projects (pool, foundations), regular professional use (landscaper, tradesperson, farmer).
CZN mini excavators for earthworks
19 models from 600 kg to 4 tonnes, reliable diesel engines and rubber tracks. Among the benchmarks: the versatile CL18S (1.8 t, €12,450), the XC18S Pro (1.8 t, €11,666) with 2.60 m of depth, the variable-track CL20S (2 t, €14,963), the Kubota-engined CL30S (3 t, €29,854), and the CL40S2C (4 t, €45,080) with an air-conditioned cab. Each machine can take a complete earthworks pack (quick hitch + ditching bucket + breaker).