Did you know that a renovation is, in reality, an exercise in shared trust? I always say that choosing who will walk into your home with a sledgehammer is just as important as the design itself. Today I want to talk to you about how to keep your dream from turning into an ordeal, using the method and the careful eye we apply at the studio.
Preliminary steps before looking for a renovation company
Before requesting quotes, define the technical scope, set a budget with a margin for error, and make sure you have the necessary documentation.
Define your expectations and the exact scope of the project
Make a detailed list for each room. Are you going to move walls or just refresh the look? We recommend having a technical professional draw up a set of plans that is as detailed as possible and write up clearly defined measurements. This way, every contractor will quote on the same basis and you’ll be able to compare one quote against another.
Being specific helps you avoid the “while we’re at it” extras that send the final cost through the roof. Decide whether you prefer aluminium joinery with a thermal break or something simpler. The more information you provide, the more accurate the quote will be.
Calculate a realistic budget (and leave a margin for unexpected costs)
A lot has happened on the geopolitical front over the past year that directly affects the construction sector. As a result, construction prices have gone up. According to ANCI’s study on the evolution of construction costs, building and civil works costs in 2025 have risen by 24% and 28% respectively, compared to costs at the end of 2020.
That’s why I always suggest setting aside an extra 15% for unexpected costs.
Right now it’s hard to pin down the real cost of materials without a well-defined project. Even tools like CYPE’s Price Generator are tricky to apply, since they’re aimed more at civil works. We use reference ranges for full renovations based on square metres and quality levels, drawn from our experience over the last few years, but in the end, you need to fully define the project before you can know the real price. What we can say is that, as a rule, don’t trust prices that are excessively low — they usually hide a lack of quality and professionalism. In our experience, we’ve come across construction firms offering prices that low because they don’t meet basic requirements, such as having staff on the payroll or the mandatory construction insurance policies. The same goes for deadlines: if they promise very short timelines but those aren’t backed up in the contract with financial penalties, that’s also a clear red flag for us.
Where to look for the best contractors
The key is to combine traditional word of mouth with enquiries at specialised suppliers and professional associations in the sector.
Word of mouth: the power of personal recommendations
Ask friends who finished their renovation more than a year ago. That way you’ll see how the finishes have aged and whether the contractor responded to any hidden defects that came up after handover.
If you spot a rooftop extension you like in your area, don’t hesitate to ask the building’s caretaker or the neighbours about the construction company. Good work is a builder’s best business card.
Ask at local construction suppliers
Professional building suppliers are the heart of the sector. They know who buys certified materials and who specialises in techniques such as dry stone walling or exposed concrete.
Stop by a building materials outlet and ask for references. A contractor who maintains a solid financial and logistical relationship with their suppliers is a sign of a financially sound and serious company.
Advice from industry professionals
As architects, we keep lists of trusted trades who strictly comply with the LOE (Spain’s Building Regulations Act). A quantity surveyor can save you thousands of euros by spotting an unreliable contractor.
The technical judgement of a chartered professional will always be objective. We don’t just assess whether the finish looks good at first glance — we also weigh up the contractor’s reliability as a company and as a collaborator: their real ability to execute the work properly, meet deadlines, and stay responsive throughout the whole process.
Online platforms, reviews and specialised directories
Use platforms like Houzz or Habitissimo, or the directory of Barcelona’s Builders’ Guild. Even Google Maps reviews can be a good indicator of a contractor’s reliability. Read the negative reviews: that’s where you’ll discover how the company handles real problems.
Pay attention to whether they respond to criticism professionally. A company that faces the public online tends to be more transparent in the day-to-day running of the project too.
7 Keys to evaluating and choosing the right contractor
Don’t choose on price alone. Check their insurance, their in-house staff, the quality of the materials, and your personal rapport with the site manager.
Never hire anyone who can’t prove they’re up to date with Social Security contributions and that they hold a current insurance policy.
1. Verify licences, certifications and public liability insurance
Ask for proof of Public Liability Insurance and a certificate confirming they are up to date with payments at the AEAT (Spanish Tax Agency). This protects you if there’s an accident on your property or if your neighbour’s flat is damaged.
Without these documents, you become secondarily liable for any legal incident. You can verify the requirement for these insurance policies in the guide published by the Fundación Laboral de la Construcción (Construction Labour Foundation).
2. Request and compare at least three detailed quotes
Don’t accept lump-sum totals. Insist on a quote with unit prices and actual measurements. If one offer is 30% cheaper than the rest, there’s probably an error in the measurements or they’re planning to use low-end materials. To avoid this, we like to itemise the measurements and define the price range for materials separately from the labour. That way, if material prices go up or down later, we know where we stand.
I often say that in architecture, cheap turns out expensive. A detailed quote is the only way to compare like with like and avoid unpleasant surprises at the end of the month.
3. Ask for real references and visit completed projects in person
Ask for contact details of previous clients. If the contractor is good, they’ll be delighted to show off their best work. We always insist on seeing a project that has been completed for at least two years.
Look at the joints, the carpentry junctions and the paintwork. The level of detail in the finishing will tell you a lot about that company’s commitment to craftsmanship.
4. Assess their team and their use of subcontractors
Ask how many operatives they have on the payroll. Ideally, the core masonry team should be in-house. Excessive subcontracting makes coordination harder and dilutes technical responsibility.
A site manager who is physically present is essential. You need someone who leads the team, not a mere “commission agent” who only shows up to collect the progress payments.
5. Value transparency, availability and initial communication
Do they answer your calls quickly? Do they explain technical solutions in plain language? Communication is the lubricant of any construction project. If they’re hard to deal with now, it will be impossible under the pressure of deadlines.
Being available to meet on site once a week is non-negotiable. Architecture is resolved on the ground, by talking through and observing each construction detail.
6. Make sure the proposed materials are of good quality
Insist on specific brands and models. A bag of generic cement is not the same as a high-bond technical mortar.
The durability of your renovation depends on what you can’t see: pipes, cables and insulation. Don’t cut corners on the internal “skin” of your home if you want it to last for decades. And of course, request the quality control documentation once the work is finished.
7. Insist on specific brands and models. A bag of generic cement is not the same as a high-bond technical mortar
You’re going to be living with the contractor for months. If there’s no rapport, or you sense they’re holding things back, don’t sign. The personal connection is your guarantee that you’ll work through problems together.
Trust your instincts. A professional who is passionate about their work will talk about materials and design with the same enthusiasm you do.
The renovation contract: what it must include to keep you protected
The contract must include the quote as an annex, a payment schedule, a delivery date and penalties for unjustified delays. The lack of a contract is the biggest reason clients end up unprotected.
A clear breakdown of costs (labour, materials and extras)
The contract must be tied to the accepted quote. Specify that no extra cost will be accepted unless you have approved it in writing in advance.
This keeps the financial discipline of the project in check. A breakdown by trade (electrical, plumbing, masonry) means you only pay for what has actually been executed and verified.
Payment plan: why you should never pay 100% up front
The usual structure is 30% at the start and the rest paid through monthly progress certifications. I always recommend holding back 5% until the final handover certificate is signed and you’ve confirmed there’s no damp or other defects.
Never pay the full amount up front. Payment should reflect actual progress on site. It’s the best way to keep the construction company committed.
The way we believe the payment system works best is through monthly certifications. That way, you only pay for what has actually been carried out.
Execution times, delivery deadlines and penalties
Setting a delivery date is essential. Include a daily penalty clause (for example, €50/day) if the project is delayed without a force majeure cause (such as strikes or extreme weather).
A project schedule or Gantt chart should be a mandatory annex to the contract. Planning is the only way you can organise your move or your interim rental with any certainty.
Managing permits, legal regulations and construction warranties
Make sure it’s clear who pays the municipal fees and who handles the building permit. The contract must include the 1-year warranty for cosmetic defects, as set out by law.
A single general contractor or several specialised tradespeople?
A general contractor centralises responsibility and coordination, whereas hiring trade by trade usually works out cheaper but requires you to act as the expert site manager.
We tend to recommend hiring a general contractor for full renovations. If anything goes wrong, you only have one point of contact. With separate trades, the plumber will blame the bricklayer and you’ll be caught in the middle of the conflict.
If you decide to coordinate everything yourself, be prepared to spend 3 hours a day on management. The 10-15% saving on management costs is usually eaten up by the personal time you lose.
Warning signs to help you avoid being scammed on your renovation (red flags)
Be wary of off-the-books payments without VAT, quotes without a breakdown, and tradespeople who don’t have their own professional tools. Paying without VAT means losing any legal guarantee.
Watch out if the contractor pushes you to buy all the materials yourself, or if they change workers every week. A stable team is a sign of a healthy, well-run company.
Frequently Asked Questions
As a private individual, am I legally required to take out construction insurance?
It’s not legally required for the owner, but it’s strongly recommended to have third-party liability insurance to avoid serious problems in case of a water leak or structural damage.
What do I do if the contractor abandons the job halfway through?
You should go to a notary to have a record drawn up of the current state of the work, send a certified legal notice (burofax) terminating the contract, and file a complaint based on the breach of the signed deadlines.
Can I change the materials once the renovation has started?
Yes, but always by signing an annex to the original quote that records the new price and how it affects the final delivery date of the project.
Who is responsible for cleaning up the rubble and construction debris?
The contractor is responsible for daily and final cleaning, as well as for managing waste at authorised landfill sites, and they must provide the owner with the corresponding certificates on request.
Is it normal for the budget to change during the work?
Only if hidden defects appear that couldn’t be detected at the outset (such as a damaged beam), or if you request changes to the original approved design.
How do I check whether the company is legally solvent?
You can request a risk report from the Mercantile Registry, or check whether they are members of well-established and reputable local professional associations.
Have you ever had a bad experience with a renovation, or did you find that “gem” of a professional who made the whole process easy? Architecture is a journey that’s better travelled with company. I’ll be reading your comments!
