Selecting a contractor for a high-value construction or renovation project is one of the most consequential decisions a property owner makes. The wrong choice costs time, money and — in the worst cases — results in structural or aesthetic damage that is expensive or impossible to correct. These seven questions will expose the difference between a contractor who operates at the level required and one who merely presents as though they do.
1. Do you subcontract any phase of the work?
Any answer other than ‘no’ requires a very detailed follow-up conversation. Subcontracting fragments accountability. Ask specifically which trades are external — and what contractual relationship exists between those parties and the main contractor.
2. Can I visit a project currently in progress?
Finished projects are always presented at their best. A live construction site reveals how a contractor actually works: site organisation, material storage, cleanliness, precision of execution at intermediate stages. A contractor who cannot or will not arrange a site visit is telling you something important.
3. What does your warranty cover and for how long?
The legal minimum under Spain’s LOE is 1 year for finishes, 3 years for habitability elements and 10 years for structure. Ask specifically what the contractor offers above the legal minimum — and get it in writing as part of the contract.
4. How are budget modifications handled?
Every project encounters unforeseen conditions. The question is not whether they will arise but how they will be managed. Any modification to the contract scope should be proposed in writing, quantified precisely and approved by the client before any additional work proceeds.
5. Who will be on site, and how often?
The technical director or senior site manager should be present daily — not visiting twice a week. Ask specifically who holds daily site responsibility and what their qualifications are.
6. Can you provide references from completed projects of comparable scale?
Ask for direct contact with previous clients — not curated testimonials. A contractor confident in their work will facilitate these introductions without hesitation.
7. What is your payment and certification structure?
Monthly certifications of completed works, aligned to the contracted chapter breakdown, are the standard for serious contractors. Lump-sum payments tied to vague milestones are a red flag.