What documents to request from a contractor before building your house

Short answer: REA, identity and contract must match

Start by requesting the full legal name, tax ID, registered address, name of the signatory and REA accreditation where applicable. Law 32/2006 requires contractors and subcontractors to have their own organisation, resources, responsibilities, prevention training and registration. Matching these details across the certificate, quote and contract helps avoid hiring one entity while another performs the work. REA is a necessary check within its scope, but it does not by itself guarantee build quality, financial solvency or a complete quotation; the rest of the file must also be reviewed.

Insurance must be verifiable, not merely mentioned

Ask for current evidence of public liability insurance and check the policyholder, insured activity, period and documentation identifying the policy. Do not assume which risks or amounts are covered: if they are decisive, request them in writing and have a professional review the exclusions. The contractor’s policy does not replace the responsibilities, guarantees or insurance that may correspond to other parties under the project and the LOE. The practical decision is to keep a verifiable copy and confirm that the insured company is the one that will sign.

Compare contractors using the same project and scope

The LOE defines the contractor through its contractual commitment to execute the work in accordance with the project and contract. Give every candidate the same drawings, measurements and specification. Ask each proposal to separate structure, envelope, services, finishes, waste management, temporary works and taxes, and to list exclusions. Provisional items should explain how they will be adjusted. A total price without quantities or quality specifications does not show whether two contractors are offering the same work.

Ask who will run the daily work and what will be subcontracted

Ask who will act as site manager, who will coordinate the trades and which parts are expected to be subcontracted. The LOE assigns the contractor the duties of appointing the site manager, allocating resources and formalising subcontracts within the limits of the contract. This does not require every task to be carried out by direct employees, but it lets you know who is accountable on site and how decisions will be communicated. Agree the contact person, meeting frequency, minutes, sample approval and change procedure before changes create cost or delay.

Put payments, changes and handover in writing

Link payments to verifiable milestones and define in writing how work quantities are certified, who approves changes and what happens if the programme changes. Do not let an advance, date or penalty sit apart from the actual scope, and obtain a professional contract review before signing. The LOE provides for a handover record identifying the parties, final cost, acceptance with or without reservations and the period for correcting defects. Also clarify which as-built documents will be delivered at completion.

What to prepare before making contact

Before making contact, prepare the plot location and details, known planning status, project or preliminary design, geotechnical study and topographic survey if they already exist, planned floor area and room programme, specification and target date. Use the same question sheet for every company: legal name and tax ID, applicable REA, insurance, site manager, intended subcontracts, scope, exclusions, programme, payments, changes and handover. The answers will then be comparable and the first conversation can focus on genuine fit rather than a figure without context.

Sources consulted

• Law 32/2006 regulating subcontracting in the construction sector
• Law 38/1999 on Building Regulation