The contractor in the LOE: the figure's obligations
The LOE defines the constructor (contractor) as the agent who contractually undertakes towards the developer to execute, with human and material means, own or others', the works or part of them subject to the design and the contract. From the definition hang its characteristic obligations: executing the works subject to the design, the applicable legislation and the site direction's instructions; appointing the jefe de obra (site manager), who assumes the contractor's technical representation and must hold adequate qualification; assigning the human and material means the works' importance requires; formalising subcontracts within the legal limits; signing the setting-out minutes and the acceptance certificate; providing the works director with the data for the building logbook; and taking out the insurance the law requires.
In the liability regime, the contractor also carries an exclusive burden: material damage from execution defects affecting completion or finishes, the first-year warranty, falls on the contractor alone. For the three and ten-year periods the contractor answers together with the other agents according to the damage's origin, with the detail developed in the article on LOE warranties and liability.
The real chain: subcontracting and its law
Execution through subcontractors is not a deviation from the system: it is the system. The main company contracts trades, structure, masonry, services, finishes, and each trade can in turn subcontract. Ley 32/2006, regulating subcontracting in the construction sector, orders that reality with three instruments.
The first is the requirements on companies: demonstrable business solvency and quality, an own productive organisation, and registration in the Registro de Empresas Acreditadas (register of accredited companies) of the corresponding region as a condition for taking part in the chain. Registration is checked before the company is admitted to site.
The second is the limitation of levels: the general regime allows the contractor to subcontract, the first subcontractor to subcontract to a second and this one to a third, placing there the ordinary limit of the chain, with stricter rules for those contributing labour only and defined exceptions for justified causes. The economic sense of the limit is direct: each link adds margin without adding production, and the law cuts the chain where the dilution of responsibility and price becomes structural.
The third is traceability: each contractor must keep on site a libro de subcontratación (subcontracting book), recording in chronological order all subcontracts with their object, level and responsible parties, accessible to the site direction, the safety coordinator and the labour authority. The book is kept current throughout the works.
| Element of Ley 32/2006 | Content | Where it is checked |
|---|---|---|
| Requirements on companies | Solvency, own productive organisation and training | Registration in the register of accredited companies |
| Subcontracting levels | Limit on successive links in the chain | The site's subcontracting book |
| Traceability | Chronological record of each subcontract, with object and responsible parties | Book accessible to site direction and labour authority |
| Liability | The main contractor answers for the chain | Contract and site documentation |
What the chain means for the works
For the works' quality and economics, subcontracting has one central consequence: the price and solvency of the main contract do not describe who will actually execute each unit. The good practices of the developer and the site direction follow from there. Knowing the chain: demanding an up-to-date subcontracting book and knowing which company executes each critical trade. Watching economic coherence: an aggressive discount by the main contractor transmits down the chain, and impossible prices reappear as trimmed quality or claims. And protecting the sensitive links: in the trades of greatest technical risk, notably structure and services, the identity and solvency of the real subcontractor matter as much as the main contractor's.
Frequent errors
The first is evaluating only the main contractor and discovering on site that the critical trades are executed by companies nobody examined. The critical trades are examined one by one before they start.
The second is tolerating an outdated subcontracting book, losing the required traceability exactly when an incident makes it necessary. Its currency is checked during the direction's site visits.
The third is admitting chains exceeding the legal levels, with the administrative and liability exposure this entails. The levels are counted from the developer down and documented.
The fourth is squeezing the main contractor's price ignoring that the pressure travels down the chain: the works that are cheap on contract are paid for in execution, and quality control, covered in its own article, then arrives to diagnose what the contract sowed. The contract price conditions the quality of the whole chain.
Note: the subcontracting regime is that of Ley 32/2006 and its implementing regulations, with registers managed by the regions; the limits and exceptions cited must be verified for each specific chain configuration.