Planning and sequencing external works

Planning external works organises tasks that depend on one another. Spreading the work across weeks is not enough. You need to know what has to be finished before the next phase, which materials need to be reserved and at what point the accesses stop being available.

In a garden with ground modelling, walls, paving, irrigation, lighting, water and mature trees, a change of sequence can mean dismantling work already done or stop the necessary equipment from getting in.

The team starts by confirming the current project documents, the levels, the measured quantities and the limits of the works. Plans, sections, details and specialist disciplines have to be coordinated.

Applicable consents and authorisations are also checked. An apparently small change can have implications for the waterproofing, the ground modelling or the proposed structures.

At this stage, materials and equipment with long lead times are identified. Mature trees, specific stone, light fittings, swimming-pool equipment or anchoring systems should not be sought only when the site already needs them.

Before excavation, limits, axes, levels and elements to be preserved are marked out. Existing trees need a protection zone that includes soil and roots, and not just a barrier next to the trunk.

The site compound, the unloading areas and the machine routes are defined so as not to compact future planting areas. Good-quality soil can lose much of its structure if it is used as a platform for traffic.

The main ground modelling comes before services and paving. Drainage is coordinated with levels and outlets. Pipes and ducts cross the paving before it is closed up.

Walls, steps and structures need foundations and curing times. Waterproofing is tested before it receives its finishes.

The largest trees go in while access for the crane and the lorry still exists. Leaving planting until after walls, balustrades or paving are finished can make it impossible to install the specimens defined in the design.

Rain changes the programme. Saturated soil should not be moved or decompacted as if it were dry, because it loses structure and compacts again easily.

Waterproofing, bonding and some finishes also require minimum conditions. The plan should allow for margin and alternative tasks, instead of trying to keep up the same output in any weather.

The season for rootballed planting is another constraint. At Diaplant, the main planting season runs from November to April, but the vegetative state of the species and the ground conditions can adjust that window.

The site needs areas for storage, unloading and circulation. Materials should not block access for the next phase.

For large trees, weight, crane reach, ground stability and the order of unloading are planned. For stone and other heavy materials, the bearing capacity of the surface and the proximity to the place of use are assessed.

A delivery out of sequence takes up space, increases handling and exposes the material to damage.

Some work should be checked before it is hidden. Buried services are tested and photographed. Levels and falls are confirmed before the finishes. Paving bases and drainage are inspected before they are closed up.

These checkpoints do not delay the works. They avoid discovering a problem when the correction already means demolition.

Each change should state the reason, the impact on the design, the cost and the time. Informal decisions on site create different versions between teams.

Short meetings, photographic records and a clear list of outstanding matters help to keep everyone working from the same information.

After the heavy works, the soil in the green areas is reviewed. The passage of machinery may have caused compaction, even when topsoil was spread at the end.

Irrigation is tested before planting. Trees go in first, followed by shrubs, perennials and ground covers. The design is marked out on the ground and adjusted only when the real conditions justify it.

Handover checks systems, finishes, drainage, stability and documentation. Construction corrections are kept separate from normal maintenance tasks.

The vegetation then begins its establishment period. Watering, staking, weeding and observation in the first months should have people responsible for them defined in the programme, and not be treated as later work with no date.

1. European Arboricultural Standards. European Tree Planting Standard.
2. European Arboricultural Standards. European Tree Pruning Standard, February 2025 version.
3. Diaplant’s method for design, construction and follow-up.