Renovating a terraced townhouse in Sarrià or Gràcia: three floors, courtyard and party wall

What is special about renovating a house between neighbours?

Such a house shares both side walls with its neighbours, light and entry come only from the front and the courtyard, and one staircase ties three levels together. So noise, vibration, loads and deliveries all pass through shared elements and a narrow street. It is not a villa in a garden or a flat in a stairwell.

The type is called a casa de pueblo or casa entre medianeras. In Sarrià and Gràcia these houses stand in dense historic fabric, and every decision in one house is felt next door. You cannot walk round the building, put a crane in the garden or hide a skip in the yard.

The first question to ask about such a house is about structure, not style: what the shared walls and floors are made of, what rests on them and what the neighbour is doing. The answer comes from an engineer's or architect's inspection, not from the look of the interior. Before buying and before the estimate, that check is cheaper than any redo.

What do you do about the party wall under Catalan law?

In Catalonia a party wall (paret mitgera) creates a special community between two neighbours: it is governed by what they agree and, failing that, by the rules in book five of the Civil Code of Catalonia. Any intervention in that wall affects the neighbour too, so before works its condition is recorded and what is acceptable is agreed.

The definition is in article 555-1: a wall raised on the boundary and on the ground of two or more properties to carry buildings or to serve as a fence. Under article 555-6, a neighbour who builds without using the wall must take adequate construction measures not to harm whoever raised it and, if harm results, compensate. Article 555-5 says that whoever demolishes a structure resting on the wall leaves it in a condition fit for future use and with the look of an exterior wall.

In practice, before starting, a condition record of walls and floors on both sides is made, with photos and a description of cracks, with the neighbour's consent, by an architect or surveyor. During the works, tell-tales are fixed across cracks and vibration is limited. Third-party liability is insured. This is not legal advice: disputed cases are for a lawyer.

How do you reduce noise through the party wall?

Decouple, do not thicken: an independent lining with its own frame, mineral wool and two layers of plasterboard, not rigidly fixed to the shared wall. Thickening the plaster or adding another board directly on the wall removes almost no noise.

The lining (trasdosado) is set off from the wall with an air gap, the perimeter is sealed, and sockets on opposite sides are not placed back to back. The lining reduces usable width on each side; the exact amount depends on the chosen construction. The loss is counted before the design, not during installation.

Noise also travels by side paths: the beam ends embedded in the shared wall, a staircase on timber stringers, a floor with no resilient layer. So a lining alone is not enough: floors are built floating and the staircase is detached from the wall. There is more on soundproofing against neighbours in our article on noise in flats; the principles are the same.

Can you rebuild the inner courtyard?

It depends on the urban plan, the plot's parameters and the building's protection. You cannot cover or build over the courtyard until you have checked your plot's regime, because the courtyard often gives light and ventilation to rooms and counts in the built area.

First request the plot's planning data from the city: permitted buildable area, courtyards required to light rooms, and the building's protection. How to do it is in the article on checking a building's protection. Glazing a courtyard or roofing it is usually treated as building, and the neighbour can object if the new roof shades their windows or changes their view of the yard.

What you can do without rebuilding: replace the paving, add drainage, fit green walls and outdoor lighting, and insulate the walls facing the courtyard. Damp at the foot of walls in a house with a ground-floor courtyard is covered in the article on ground-floor flats with a garden.

What should you consider when adding height or touching the floors?

The permitted height and buildable area are set by the plan, and an old house's floors have to be checked by calculation. An extension or an extra level runs into both limits and into the neighbour's rights: the shared wall cannot always be raised, and not without agreement.

In houses of this type the floors are usually timber beams or brick vaults, and the load-bearing walls are stone or brick. A floor may not carry the load of new stone paving, a stone bath, a lift or an attic room. Before the design a survey is carried out: trial openings, deflection measurements and an assessment of the beams. The result decides whether the structure is kept, strengthened or replaced.

The staircase of such a house remains the centre of the structure and of safety: its width, pitch and balustrade affect any rearrangement. What to consider when redoing a staircase and mixed levels is in the article on duplexes and triplexes. A lift in a single-family house is handled separately and needs a shaft.

How do you organise the work when the plot is narrow?

Small vehicles on a schedule, storage inside the house, hoisting through a facade window, and an approved occupation of the street. On a narrow street you cannot unload an articulated lorry and leave it for a day.

A skip, scaffolding or a hoist in the street needs the city's permit to occupy public space, and its lead time goes into the schedule. Materials arrive in batches within the street's clearance, and some are cut on site. Waste leaves in bags, and the skip is placed where it does not block the way. In Gràcia in mid-August, during the Festa Major, the streets are taken up by decorations and crowds, so deliveries are planned ahead.

Noisy phases and dust are agreed with the neighbours: a note with dates, a barrier at the doors and daily cleaning. Good relations with the neighbours matter more than any schedule, because a single complaint can stop the work.

How do you start renovating a terraced house if you do not live in Barcelona?

Commission an inspection of the structure and of the party wall's condition before signing the estimate, and keep in touch with one person responsible on site. Without that, surprises come at the opening-up stage, when fixing them costs more.

BCN YARD runs projects in Russian and Spanish: one person is responsible for the project, with our own crew and trusted subcontractors, and payment is by stages under a contract. As a price guide: Premium from 1,000 €/m², Luxury from 2,000 €/m² and Signature from 3,000 €/m², excluding VAT; the exact price comes in the estimate after a visit and measurements. VAT on renovating a resale home in our estimates is usually 21%. The 21% applies because in our renovations materials usually exceed 40% of the taxable base; when they do not, renovating a private individual's home is taxed at 10% (Law 37/1992, art. 91). We reply to an enquiry within an hour.