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Site works: preparing the site for construction
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Site works: preparing the site for construction

7 min readBy Structonix Sistem Global S. L.

Site works: preparing the site for construction

Земельные работы — это первый этап, когда строительство становится физически видимым на участке. Появляется техника, начинается разметка, выемка грунта, подготовка основания и организация стройплощадки.

Но этот этап нельзя воспринимать как простое “выкопать землю”. От качества земельных работ зависит фундамент, структура дома, отвод воды, сроки и будущий бюджет. Ошибки здесь часто становятся заметны только позже, когда исправлять их уже дороже и сложнее.

1. Site preparation work begins before the machinery arrives

Before the excavator arrives on site, it is necessary to prepare not only the ground but also the relevant information. The team must understand exactly what to dig, where the boundaries lie, what elevations are specified in the project, and what risks exist on the site.

Before work begins, it is important to check:

  1. The current project documents and site plan.
  2. The exact site boundaries.
  3. The layout of the future house.
  4. Elevation levels.
  5. The existing terrain.
  6. Access for machinery.
  7. Storage areas for materials and excavated soil.
  8. The presence of old structures, pipes, cables or hidden obstacles.

An often-overlooked point: if the levels are set incorrectly at the start, the error can carry through to the foundations, floor levels, stairs, terraces and the entrance to the plot.

2. Marking out is one of the most important steps

The site plan shows exactly where the house will be situated. At this stage, it is important not just to have a ‘rough idea’ of the layout, but to transfer the design precisely onto the plot. The following are checked:

  1. The position of the house in relation to the plot boundaries.
  2. Setbacks from neighbours’ properties and the road.
  3. The building’s axes.
  4. Angles and geometry.
  5. The level of the future floor.
  6. The position of terraces, the swimming pool, retaining walls and the driveway.
  7. How the house relates to the site’s topography. Errors in the layout can result in the house not being situated where planned, or lead to problems with setbacks, the level of the entrance, terraces and utility connections.

3. Excavation and preparation of the sub-base

During the earthworks stage, it is important to monitor not only the volume of earth but also the quality of the subgrade, the depth and shape of the excavation or trenches, as well as the behaviour of the soil. It is important to check:

  1. Whether the depth complies with the design.
  2. The quality of the soil at the actual elevation.
  3. Whether there are any weak, loose or backfilled areas.
  4. Whether water is seeping in.
  5. Whether the trenches and excavations have been formed correctly.
  6. Whether adjacent areas of the site have been disturbed.
  7. Whether additional reinforcement or adjustments to the design are required. A point that is not immediately obvious: the actual soil conditions may differ from expectations. If, after excavation, it becomes apparent that the subsoil is weak or unstable, work must not simply continue ‘as planned’ without a technical assessment.

4. Site gradient and retaining walls

Sloping plots are common in Spain. Whilst they can offer beautiful views, they almost always complicate groundworks. On sloping plots, the following must be taken into account in advance:

  1. The volume of earth to be excavated and backfilled.
  2. The need for retaining walls.
  3. Drainage and rainwater run-off.
  4. The stability of the slopes.
  5. Access for machinery to different levels.
  6. The future levels of the house, terraces, swimming pool and car park.
  7. Additional structural calculations. A sloping plot requires particularly careful planning. Otherwise, part of the budget may be spent not on the house itself, but on stabilising the land, levelling the site and rectifying drainage issues.

5. Water on the plot

Water is one of the main risk factors during the groundworks stage. Even if the site is dry on the day of the inspection, it is important to understand where water will flow during rainfall and how it will be drained away after construction. It is important to pay attention to:

  1. Signs of waterlogging.
  2. The direction of natural water flow.
  3. The presence of neighbouring plots situated higher up on the terrain.
  4. The need for drainage.
  5. Stormwater drainage.
  6. The risk of foundation scouring.
  7. Protection of the future foundation and retaining walls. A point that is not immediately obvious: water may come not only from your plot, but also from neighbouring plots, the road or the upper part of the slope. This must be taken into account before laying the foundation.

6. Safety in earthworks

Earthworks involve machinery, changes in elevation, trenches, excavations and the risk of soil collapse. Safety measures must therefore be put in place from the very start. The following must be monitored:

  1. Safe access to the site.
  2. Areas where machinery is operating.
  3. Barriers around hazardous areas.
  4. The condition of slopes and trenches.
  5. The distance between the soil stockpile and the edge of the excavation.
  6. Weather conditions.
  7. The presence of people near machinery in operation. Spanish health and safety requirements on construction sites are regulated by Royal Decree 1627/1997, whilst the INSST publishes technical guidance on risk assessment and prevention in the construction industry, including work in trenches and the prevention of collapses.

7. Soil removal and logistics

Soil excavation almost always involves logistical considerations. The soil must either be used on site, temporarily stored, or removed. Before work begins, it is important to decide:

  1. How much soil needs to be removed.
  2. Whether some of the soil can be used for levelling the site.
  3. Where to store the soil temporarily.
  4. How vehicles will access the site.
  5. Whether the machinery will block neighbours’ access or the road.
  6. How many trips will be required.
  7. How the removal of soil will affect the budget and timetable. One point that is not immediately obvious: soil removal can become a significant expense, particularly if the site is complex, access is narrow, or the volume of soil to be excavated turns out to be greater than initially estimated.

8. What to check before moving on to the foundations

Once the groundworks have been completed, you must not proceed straight to the foundations without carrying out a check. This stage must be formally recorded and technically approved.

  1. The house has been marked out on the plot in accordance with the plans.
  2. Boundaries and setbacks have been checked.
  3. Depths and levels comply with the plans.
  4. The site is suitable for further work.
  5. There is no water or unforeseen issues with the ground.
  6. The areas for the foundations have been prepared.
  7. It is clear how drainage and water discharge will be organised.
  8. Photographic records of concealed stages have been taken.
  9. Access for the necessary machinery and materials has been checked.
  10. All outstanding issues have been resolved before the start of foundation works.

The STRUCTONIX Approach

At STRUCTONIX, we regard groundworks as the technical foundation of a future home. This is a stage at which it is important not simply to prepare the site, but to check the levels, the soil, the water, access for machinery, and how the future building will connect to the plot. Properly carried out groundworks help to avoid problems with the foundations, retaining walls, drainage and the rest of the house’s structure. Construction must proceed in a logical sequence: the plot, site marking, groundworks, checking the sub-base, the foundations, and only then the structure. In the next article, we’ll look at the foundations: what’s important to check before pouring the concrete and why this stage must not be rushed without proper supervision. Stay tuned and keep an eye on updates to the STRUCTONIX blog.

Sources and useful links:

  1. Royal Decree 1627/1997 — health and safety on construction sites, BOE: https://www.boe.es/buscar/act.php?id=BOE-A-1997-22614 — minimum health and safety requirements on construction sites.
  2. INSST — Technical Guide for the Assessment and Prevention of Risks on Construction Sites: https://www.insst.es/documentacion/catalogo-de-publicaciones/guia-tecnica-para-la-evaluacion-y-prevencion-de-los-riesgos-relativos-a-las-obras-de-construccion-ano-2019 — official guidance on risks at construction sites.
  3. INSST — NTP 278 Trenches: prevention of landslides: https://www.insst.es/documentacion/colecciones-tecnicas/ ntp-technical-prevention-notes/8th-series-ntp-numbers-261-to-295-year-1992/ntp-278-trenches-prevention-of-landslides — recommendations for preventing landslides in trenches.
  4. CTE DB SE-C — Structural Safety: Foundations: https://www.codigotecnico.org/pdf/Documentos/SE/DBAnteriores/DBSE-C_200801.pdf — technical requirements for foundations.
  5. Málaga City Council — building procedures: https://urbanismo.malaga.eu/tramites/obras/ — municipal procedures for building works and planning permission.