Phases of a construction project in Spain: from basic design to handover

Before entering each phase, the general map. The names matter, because each term designates a document or act with precise legal effects.

Two ideas run through the whole process. First: each phase freezes decisions and makes later changes more expensive, so optimisation power is maximal at the start and minimal at the end. Second: the LOE assigns each agent defined functions and responsibilities, and a good share of site conflicts are born from confusing them. The design phases are developed in detail in the article on the design phases and their documentation, and the distribution of roles in the one on the building agents under the LOE.

The least regulated phase of the process is also the most decisive. Before the first formal drawing, the developer and their consultants set the brief, check the site's planning feasibility, estimate the economic envelope and take the structuring decisions: how much area, which uses, what quality level, what target budget. The anteproyecto translates those decisions into an overall architectural solution, still without permitting value, but already with almost irreversible economic consequences: the shape, the compactness, the position of the cores and the structural system are sketched here, and with them the order of magnitude of the cost.

Serious professional practice accompanies this phase with early cost estimates by ratios and areas, precisely because it is the only moment when changing one's mind is free. Preliminary studies and the anteproyecto have their own article, with the detail of each stage's decisions.

The proyecto básico is the first document in the process with regulatory status. It defines the building completely in its essentials, location, areas, uses, general configuration, planning compliance, and its characteristic function is to enable the application for the works licence. What the básico does not allow is building: it lacks the construction detail, the developed services and the quantities that execution demands.

That asymmetry turns the básico into a schedule management tool: processing the licence with the básico while developing the detailed design in parallel is the usual mechanism to shorten the total calendar. Its content, exact scope and limits are developed in the article on the proyecto básico.

The proyecto de ejecución develops the básico to the level that allows the works to be executed: detail drawings, complete construction report, justification of compliance with the CTE (Código Técnico de la Edificación, the Spanish building code) and the rest of the applicable regulations, specifications, the health and safety study, and the economic block, the mediciones (bill of quantities) and the budget. It is the document against which one contracts, executes, certifies and, if it comes to it, litigates: its documentary quality is directly proportional to the economic tranquility of the works.

For the construction economist, the proyecto de ejecución is the central piece of the process: complete, well-structured quantities are the basis of a reliable budget, a clean tender comparison and certifications without surprises. The article on the proyecto de ejecución develops its documentary content and the role of the quantities.

The LOE organises the process around agents with defined functions: the promotor (developer), who drives and finances the operation and bears central liability towards purchasers; the proyectista (designer), author of the design; the constructor (contractor), who executes the works with own or subcontracted means; the director de obra (works director), who directs the technical, aesthetic and planning aspects of execution in accordance with the design; the director de la ejecución de la obra (execution director), who takes on the quantitative and qualitative control of what is built; and alongside them the quality control entities and laboratories, the product suppliers and the final owners and users. Each agent answers for its own role and no function transfers by private agreement.

In ordinary residential building, the characteristic professional pair is the arquitecto, designer and works director, and the arquitecto técnico (technical architect), execution director, whose coordination is examined in the article on the distribution of functions between architect and technical architect. The obligations of each agent, starting with the developer, and those of the contractor with its subcontracting chain, complete the branch.

No project builds without an enabling title. The classic route is the municipal planning licence, an express resolution of the town hall after checking the design, whose processing, documentation and real timescales are analysed in the article on the works licence. For lesser works, state legislation and regional regulations have generalised the declaración responsable (responsible declaration) and prior communication, regimes in which the applicant declares compliance and may start without waiting for a resolution, assuming in exchange the risk of subsequent control; the exact split between licence and responsible declaration varies by region and municipality, and its logic is developed in the article on the responsible declaration.

The third characteristic formality is the visado colegial (professional body validation), the formal control of the professional college over the technician's work. Since Royal Decree 1000/2010, the visado is voluntary as a general rule and obligatory only for the works listed in its article 2, notably the proyecto de ejecución of building works and the final works certificate. The article on the visado colegial details the cases and what the validation contributes outside them.

With licence and contract, the works formally start at the setting-out verification minutes. From there, three systems run in parallel throughout execution.

The first is the dirección facultativa: the works director and the execution director, each with their functions and documents, from the site order book to the certifications, whose mechanics are developed in the article on works direction and execution direction. Both directions run throughout the works and are not interchangeable.

The second is quality control: the control programme, material testing, accredited entities and laboratories, and the documentation of results that will end up integrated in the building logbook. The article on quality control on site walks the system and its cost.

The third is cost tracking: the monthly certification of executed works, the management of changes and new rates, and the control of deviations against the contract budget, covered in the article on certifications and cost tracking. The site minutes, from setting out to completion, document the milestones of the process.

The works end legally in two chained acts. The certificado final de obra (final works certificate), signed by the site direction and validated, attests that the works are complete in accordance with the design and the regulations. The acta de recepción (acceptance certificate), between developer and contractor, with or without reservations, transfers possession, opens the warranty periods and starts the economic settlement clock. The article on handover and the final certificate develops timescales, reservations and effects.

From acceptance run the LOE warranties, with their characteristic three-period structure: one year for completion or finishing defects, with the contractor as the liable party; three years for damage compromising habitability; and ten years for structural damage, that affecting foundations, supports, beams, slabs or load-bearing walls and compromising the building's strength and stability. On this last period rests the ten-year damage insurance, obligatory in residential building, whose mechanics, technical control body included, are detailed in the article on the ten-year insurance. The complete map of warranties and liable parties is analysed in the article on LOE warranties and liability.

The building's delivery is completed with its documentation: the libro del edificio (building logbook), which gathers the final design with its modifications, the minutes, the intervening agents, the use and maintenance instructions and the quality control documentation. It is the property's manual for its whole service life, required by the LOE and developed by regional regulations, and its version for the existing stock, the libro del edificio existente of Royal Decree 853/2021, has become a key piece of publicly funded renovation. Both are covered in the articles on the building logbook and the existing building logbook.

With the phases walked, the economic synthesis fits in three rules. All three apply from the appointment rather than when the budget is closed.

The first is the funnel rule: the capacity to influence cost falls at each phase, from one hundred percent at the preliminary studies to almost nothing at handover. The decisions that are expensive to correct, brief, shape, structural system, quality level, are all taken before the proyecto básico. Budgeting early is not a luxury: it is the only cheap lever of the process.

The second is the document rule: every euro of the works rests on a document from an earlier phase, and the quality of that document determines the solidity of the euro. Incomplete quantities produce conflictive certifications; imprecise basic designs produce licences with requirements; contracts without clear specifications produce litigious settlements.

The third is the agent rule: the LOE has distributed responsibilities so that every risk has an owner. Knowing that distribution is not legal erudition, it is applied risk management: knowing who answers for what, and for how many years, orders everything from the works contract to the claim for a defect.