How to choose a good contractor is a question that almost always comes up once the quote is already on the table, with little information to read it.

Since the 2008 crisis, the construction sector in Spain has changed: the companies that closed gave way to many self-employed builders and small crews who now carry out a large share of renovations. Many of them are very good. But the heavier the workload on such a fragmented sector, the more quotes and workmanship vary, not through bad faith, but through lack of scale, of intermediate supervision and, sometimes, of time.

This isn’t a list for suspecting everyone. It’s the opposite: these are the specific signs that, when they appear, deserve one more question before you sign.

How to choose a good contractor: warning signs in the quote

A lump sum with no breakdown of items. A clear quote details the work, the areas and the materials with their specifications, not a round “turnkey” figure with no explanation of what it’s made of.
Generic items such as “miscellaneous materials” or “general labour”. Without specifying which material, which brand or what quantity, that line can absorb any cost later on.
The first figure you’re shown doesn’t include tax, and this is only clarified at the end, or not at all. Always compare two quotes with the full price, tax included.
Preparatory work left out: demolition, debris removal and landfill fees. If they aren’t in the initial quote, they tend to reappear later as an “unexpected extra”, when in fact they’re a necessary part of any renovation involving demolition.
Unjustified price rises once work has started, on materials that were already fixed in the signed quote.

A question that helps you see who you’re dealing with: ask them to explain what specific solution they’ll use for thermal insulation or noise protection in what they’re renovating. Spain’s Building Technical Code (Código Técnico de la Edificación) sets requirements for both (basic documents DB-HE, energy saving, and DB-HR, protection against noise), and in a renovation DB-HE applies to the parts of the building envelope that are replaced or modified. Someone who works with sound judgement can name the material and the solution they use; if the answer is vague, it’s worth asking them to specify it in writing.

Warning signs in payment

A deposit above 30 % of the total. OCU (Spain’s consumer organisation) puts the reasonable limit at around that figure (between 20 and 40 %, depending on the guide). The sensible approach is to pay as each phase is completed and to settle the balance when the work is fully finished, down to the last detail.
Insisting on cash payment without an invoice. OCU points out that the invoice is your guarantee to make a claim if there are problems, and that payments of €1,000 or more cannot be made in cash.
Pressure of urgency (“the discount only applies if you sign today”) to close the deal before you can compare or think it over calmly.

Warning signs in the business relationship

No tax ID (NIF), company name or verifiable address. It’s the simplest sign to check and one of the most useful.
No civil liability insurance for their activity.
No references from previous jobs that can be checked.
Suggesting you skip the building permit or the responsible declaration when the renovation requires it. It saves time in the short term and shifts the risk to the owner: work carried out without the required municipal authorisation can even end in a demolition order.

What should a renovation quote include?

Full tax identification of the company or self-employed builder (NIF, address).
A detailed description of the work, areas and materials with their specifications.
Start and finish dates, and what happens if they aren’t met.
The full price including tax, and a payment schedule tied to completed, verifiable phases of the work, not just to calendar dates.
The guarantee period and how to make a claim, in writing.

The real advice

The cheapest of the three quotes you ask for is almost never cheapest because of efficiency: it usually is because something is missing, whether it’s the preparatory demolition and debris work, the real breakdown of specifications, or the margin for the unforeseen that every job has. Comparing three quotes on the final figure, without first comparing what each one includes item by item, is the most common way to choose “the cheap one” and end up paying the same (or more), just spread across extras that weren’t on paper.

What to do if the renovation is already under way and something doesn’t add up

None of the above replaces checking, phase by phase, whether what you’re paying for matches what you contracted. That’s where most mismatches get resolved, before they turn into a bigger problem at the end of the job. It’s what Renovation Follow-up does, milestone by milestone: documenting each phase before it’s paid, instead of discovering the difference between what was agreed and what was built on the last day. Everything may well be going fine, and often it is; what it adds is checking it in time.

Sources

If your renovation is under way and you’d like someone keeping an eye on it, let’s talk.

How to Tell If the Contractor You’re About to Hire Is Trustworthy, Before You Sign the Quote