Who is the jefe de obra and how is the role different from the aparejador?
The jefe de obra is the contractor's representative on site: they organise people, materials and the schedule. The aparejador (arquitecto técnico) usually acts as the execution director and checks that what is built matches the design and the expected quality. One does the work, the other controls it, and they sit on opposite sides.
The Spanish Building Act (LOE, Ley 38/1999) obliges the contractor to appoint a jefe de obra whose qualification or experience suits the complexity of the works and who represents the contractor technically on site. The execution director (art. 13) is part of the technical management team and independent of the contractor: the promoter hires them. If one person plays both roles, there is no control, because the checker and the doer are the same. In a luxury renovation this is a well-known source of quality disputes that surface too late.
Who is who on a site under the law?
The LOE names five roles. The promoter (art. 9) decides, plans and finances the works and obtains the licences. The designer (art. 10) drafts the project. The contractor (art. 11) carries out the works with its own or subcontracted resources. The works director (art. 12) answers for the technical, aesthetic and planning side. The execution director (art. 13) controls the material execution and quality.
If you commission a renovation, you are the promoter in legal terms, even if you are not a developer. That means licences and reception of the works fall on you, not on the contractor, although they are normally handled together. The works director and the execution director, together with the designer, form the technical management team (dirección facultativa); what it controls and how it is hired is covered in a separate article. The works director signs the start record and the final certificate; the execution director verifies materials, signs interim certifications and records instructions in the site log.
The project manager is not named in the LOE. That role is built by contract, not by law.
What is a project manager and does the client need one?
A project manager handles schedule, budget and coordination, and has no right to sign technical documents unless the role is combined with a qualified profession. You need one when the project is large, there are several contractors and the owner is far away. If a single contractor with a single responsible person runs the renovation, a separate manager is often redundant.
Distinguish two variants. A client-side PM is independent of the contractor, represents your interests, and checks quotes, schedules and invoices. A contractor-side PM is its employee who runs the project internally; useful, but not an independent controller. When a contract says project management, clarify whose person this is and who they answer to.
An independent PM makes sense if you assemble the project from several trades (gremios) and do not want to hand overall responsibility to anyone; that route has a separate article. They are paid under a contract, often a percentage of the works cost or a fixed fee, and terms are negotiated. If you have one, they do not replace the execution director; they work alongside.
Who is liable for mistakes on site?
Under the LOE (art. 17), each party is liable for damage from its own errors, counted from the date of reception: 10 years for defects in foundations and structural elements that threaten stability, 3 years for defects in building elements or services that breach habitability requirements, and 1 year for finish defects (this period applies to the contractor). Liability is individual, and joint if the cause cannot be established or several parties are at fault.
For a renovation this means the following. A design error lies with the designer. An execution error lies with the contractor, and if the controller missed what they were bound to notice, with the execution director as well. The client, as promoter, is jointly liable to buyers for construction defects. Force majeure, the acts of third parties or of the injured party are excluded.
The LOE does not apply to every renovation: it covers new construction and certain interventions in existing buildings. For light works that do not touch the structure, liability rests on the contract and general civil law, and the details are worth checking with a lawyer. That is why warranty terms, deadlines and the handover procedure are better written into the contract than left implied.
Who should you contact if the owner lives abroad?
For day-to-day matters, the jefe de obra or the single responsible person at the contractor. For technical disputes over quality, the execution director. For design changes, the works director and the designer. For money, the text of the contract and the certifications.
Agree four things in advance. Who on site makes decisions on your behalf and up to what amount; where necessary owners grant a power of attorney for this. How often reports arrive: in practice weekly photos and video with a short note on what was done and the next step. How instructions are recorded: in the site log (libro de órdenes), in writing, not in conversation. Which language you receive documents in: the quote, records and certifications in a language you read fluently.
Remote oversight works if there is an independent pair of eyes. The execution director signs what they have seen themselves, and their report on materials and phases gives you grounds to pay a certification. Pay by stage, not for promises.
How do you choose a hiring structure: contractor plus management team, or everything through a manager?
There are three workable structures, and each has its own price when something fails. First: one contractor for everything and an independent technical management team hired by you. Second: contractor and designer working in tandem, with project signatures and control remaining with independent specialists. Third: an independent PM and separate trades.
The single-contractor structure gives one point of responsibility and fewer joints between works; its drawback is that without independent control you check the contractor on the contractor's word. The contractor-designer pairing speeds up decisions if the designer is genuinely independent in signature. The PM-and-trades structure is cheaper on paper and harder to manage: each trade answers only for its own section, and someone has to run the joints between them. If you are not in Spain, the last is the riskiest.
How the house design and the interior design connect is explained in another article. In a luxury renovation it matters that all three roles know each other by name and work from one set of drawings.
How does BCN YARD set this up, and what should you ask any contractor?
At BCN YARD one person is responsible for the project, with our own crew and trusted subcontractors. We run projects in Russian and Spanish, answer an enquiry within an hour, and payment follows the contract, in stages. Project signatures and the technical management team come from independent specialists, and we work from their documents.
Five questions for any company before a contract. Who will be your jefe de obra, by name, and how many sites do they run at once. Who is the execution director and who hires them. How certifications are issued and which documents you pay against. How you receive reports and in what language. What the contract says about handover and rectification of defects. A contractor who answers these at once and without generalities usually runs the build the same way.
We will show how this looks on real projects, for example the Urgel flat in the Eixample (109.80 m²) or a private house with a pool. Write to us and we will explain how we would split the roles on yours.
Frequently asked questions
Who is the jefe de obra and how does the role differ from the aparejador?
The jefe de obra represents the contractor on site: people, materials, schedule. The aparejador usually acts as the execution director: independent of the contractor, checking quality and materials and signing certifications. One does the work and the other controls it, so both roles should not rest on one person.
Does the client need an independent project manager?
It is needed on a large project with several contractors and an owner who is not in Spain. If one contractor with a single responsible person runs the renovation and independent technical control exists, a separate manager is often redundant. Ask whose person holds the PM title: yours or the contractor's.
Who is liable for errors on a building site?
Each for their own: the designer for the design, the contractor for execution, the execution director for missed control. Under the LOE periods run from reception: 10 years for structure, 3 years for services and habitability, 1 year for finishes on the contractor. For light works outside the LOE the contract and civil law apply.
Who do I contact if the owner is abroad?
For day-to-day matters, the site manager or the contractor's responsible person; for quality, the execution director; for design changes, the works director. Agree in advance on weekly reports, written instructions in the site log, and who decides on your behalf, possibly under a power of attorney.