Short answer: cheaper in total, dearer per metre
A partial renovation costs less than a full one in total, but per square metre it is almost always more expensive. Fixed costs for mobilisation, protecting the building, waste removal, permits and coordination are spread over a smaller area, and the rooms most often renovated on their own are the kitchen and bathroom, the most expensive rooms in any home.
Our benchmarks for a full renovation: from 1,000 EUR/m² at Basic, from 2,000 EUR/m² at Standard and from 3,000 EUR/m² at Luxury, excluding VAT. A kitchen or bathroom on its own is priced by estimate and per metre usually comes out above those figures.
Where the difference comes from
Every renovation has costs that barely depend on area: protecting the entrance and lift, the skip, the permit, dealing with the comunidad de propietarios, the site manager's organising time, call-outs for the electrician and plumber. On a whole-flat job they dissolve into the total. On a single kitchen they are a visible share of the bill.
The second reason is the type of room. A bedroom is walls, floor, sockets and a door. A kitchen or bathroom is pipes, drains, waterproofing, tiling, units, appliances and a dozen hand-offs between trades. A metre of wet room costs far more than a metre of bedroom, and when an estimate covers only wet rooms, the average per metre climbs.
The invisible link through the services
A home works as one system. A new kitchen with an induction hob, oven and dishwasher needs power that old wiring and an old consumer unit may not handle. A new bathroom connects to pipes that, from the supply to the bathroom wall, are still the originals. New parquet in the living room meets old parquet in the hall, and a threshold or a change in level appears between them.
In an Eixample building this is especially visible: the services have often been changed piecemeal by different owners, and a partial job adds one more layer. When an old pipe inside the hallway wall fails two years later, it gets replaced through the new finishes.
Two renovations instead of one
Each later stage pays again for what the first one already paid for: moving furniture out, protecting finished rooms, the dust that still gets into the completed part, the skip, the arrangements with neighbours and sometimes a new permit. And you live on a building site twice, or rent somewhere else twice.
If two or three partial jobs add up over five years, one full renovation would almost always have been cheaper and a great deal calmer.
When a partial renovation is the right call
If the flat's services are recent, the layout works and only the kitchen or one bathroom has aged, there is no reason to renovate the whole home. A typical case: a house in Castelldefels where the electrics and plumbing were redone a few years ago and the kitchen is the previous owners'. The sensible move is to replace the kitchen after checking the circuit capacity and the condition of the drain.
A partial job also fits when the flat is let and one room needs refreshing between tenants, or when this year's budget only covers one area. The condition is to check before starting that the neighbouring systems can take the new work.
What to ask before a partial renovation
Before signing an estimate for a single kitchen or bathroom, ask the contractor five questions. Will the consumer unit and circuit cope with the new appliances? What are the pipes made of between the flat's supply and this room, and what state are they in? Will the new floor sit level with the adjoining rooms? Does the shared stack need touching, which means talking to the comunidad? How will the rooms you are still living in be protected?
If the answer to two of those five is we will see after strip-out, build a contingency into the budget or widen the scope.
Staged renovation under one design
If you want the result of a full renovation but not yet the budget, design the whole flat at once and build it in stages. The first stage then lays in what the later ones need: a consumer unit sized for the whole home, pipes to the future bathroom, routes for air conditioning and a single floor level.
Start with the messy and hidden work: services, partitions, screeds. Finishes can be spread out. At BCN YARD we design these flats as a whole and deliver them in coordinated stages. Ask us, or any contractor, for two estimates on the same property: the full renovation and the sum of the partial ones. The comparison usually makes the decision for you.