Where a house renovation starts and what it costs
A detached house renovation starts with a survey of structure, roof, damp and services; the design comes afterwards. As a reference for interiors we work with three levels, excluding VAT: Basic from €1,000/m², Standard from €2,000/m² and Luxury from €3,000/m². A 200 m² house at Basic level therefore starts at around €200,000.
Facade, roof, garden, pool or retaining walls are not part of the interior price per square metre and are quoted item by item. In a house the split between inside and outside weighs far more than in a flat, and the final price is fixed in the estimate after the visit and measurements.
What to check in a 1970s or 1980s house
Many houses in Castelldefels, Garraf and Maresme were built between the 1970s and 1990s, before today's insulation requirements. What we find most often: uninsulated facades and roofs, aluminium windows with no thermal break, wiring without a reliable earth, iron pipes and ground floors with rising damp.
If the roof or a downpipe is made of fibre cement, its removal is carried out by a company listed on the official asbestos-risk register (RERA), under its own work plan. This is not something to improvise: it is identified during the visit and included in the quote from the start.
Keep or rebuild: the decision that sets the budget
In an existing house every element faces the same question: does it work and can it be integrated, or is it better replaced now that the site is open? A solid masonry staircase, a terrazzo floor in good condition or sound timber beams can stay and add character. An underground drain network with roots inside cannot.
The practical rule: anything that will be hidden behind new finishes is renewed if it is more than thirty years old, because opening it again in five years will cost more than doing it now. Whatever is visible and in good shape is assessed case by case. We have a separate article on which existing features are worth keeping.
Extending or changing use: planning rules first
Turning a garage into a studio, enclosing a porch or adding a storey depends on the buildable area and site coverage that planning rules allow on that specific plot, not on what the neighbour did. Some houses have already used up their buildable area and others are classed as non-conforming (fuera de ordenación), where permitted works are limited.
Before drawing the extension, ask the architect to check the plot's planning rules with the ayuntamiento. In a flat the building envelope is almost never touched; in a house it is exactly what changes the project most. We cover extensions in detail in a dedicated article.
Envelope and energy: where comfort is won
On the Barcelona coast, the problem with an old house is usually summer heat rather than cold. Insulating the roof, replacing windows with thermally broken frames and adding solar shading on the south and west facades changes comfort more than any air-conditioning unit.
If the renovation is a full one, this is the moment to consider aerothermal heat pumps, underfloor heating or solar panels, because the services are being rebuilt anyway. In the house with a pool we built between 2022 and 2024, the solar panels were part of the project from day one, not a final add-on, so the roof, cable routes and electrical panel were designed only once.
How we run the works on a house
The usual sequence: survey and measured drawings, design and municipal permit, selective demolition, structure and roof, services, windows and enclosures, finishes and exterior. The garden and pool come last, but their water, power and drainage connections are prepared during the services stage.
Our own crew does the work, specialist trades go to trusted subcontractors, and a single site manager talks to you in Russian or Spanish. Payment is by stages under the contract. If the house is an hour from Barcelona, lorry access and material storage are sorted out on the first visit, not on the day of the first delivery.
Next step
Send us the approximate address, photos of the facades, roof and interiors, drawings if you have them and a list of what you want to change. We reply within an hour. On the visit we check structure, damp and services and tell you what is feasible before proposing a design.