What earthworks are and why they matter
Earthworks bring the plot to the levels set in the project: ground is cut or filled, foundations and basement are excavated, and the formation is compacted. The result is a firm platform at the right height, and everything built on top depends on how accurately this stage is done.
From the street it looks simple: an excavator, lorries and dust. In practice the stage follows two documents to the letter: the project with its levels, and the geotechnical study, which says how deep the bearing stratum is and how the ground behaves. We explain the difference between a topographic survey and a geotechnical study in a separate article.
The sequence of works on the plot
First the plot is cleared of vegetation, debris and any old structures. Then comes setting out: the surveyor marks the building grid and levels from the project on the ground, and the site supervision team (dirección facultativa) checks that the house sits where it is drawn, with the right distances to the boundaries.
Next comes excavation for foundations, basement or pool, filling where the ground is below design level, and compaction in layers. Each layer is compacted separately; you do not tip a metre of soil in one go, or the terrace paving will sink within a couple of years. Finally the formation levels are checked before foundation work starts.
Sloping plots: Garraf, Castelldefels, Maresme
The province of Barcelona has plenty of hillside plots. On them, earthworks almost always include retaining walls and sometimes terracing. Later they are hidden by the garden and the facade, but they are what holds up the house, the drive to the garage and the pool.
A retaining wall is designed and calculated by a qualified engineer, not built by eye. It needs drainage behind it; otherwise rainwater pushes on the wall and eventually finds its way out through the basement. Soil cut from the top of the plot can sometimes be used as fill lower down, but only if the geotechnical engineer confirms it is suitable.
Ground surprises and how to respond
The study samples a few points; the excavation opens up the whole plot. So things turn up that the report did not show: rock that has to be broken, old rubble fill, groundwater higher than expected, remains of old foundations or services.
The right response is always the same: stop, call in the site supervision team and the geotechnical engineer, and get a solution and a clear price before carrying on. BCN YARD tells the client about a change like this before continuing, not afterwards on the invoice. Expensive mistakes start when poor ground is simply covered over to avoid losing a day.
Spoil, neighbours and machine access
Surplus soil goes to an authorised tip, and it is a significant cost item: volume, number of loads and distance are priced separately. If some of the soil will be needed for landscaping, it is stockpiled on the plot, but where it does not get in the way of the works or load a slope.
This stage is noisy and dusty. Warn the neighbours in advance, keep the street clean and plan the lorry route together with site access. A narrow street on a slope can limit the size of machinery, which immediately affects the programme. Requirements for working on the public road are checked with the ajuntament.
What the owner should check at this stage
Ask for three things. The setting-out record, or confirmation that the grid and levels have been checked by the site supervision team. Photos of the excavation with the soil layers visible before any concrete is poured. Confirmation from the geotechnical engineer or site director that the bearing ground matches the study.
On a full-cycle build, such as the private house with pool that BCN YARD delivered between 2022 and 2024, it pays to plan earthworks for the house, the pool and buried services as a single stage. Machinery comes onto the plot once rather than returning a year later to dig up a finished garden. Each project has one person in charge, and payments follow contract stages.