Investment approach
The 30% Quota and the 600 m² Threshold: Small Project and Villa
The 600 m² threshold applies to the plot, not the project: the 30% is taken from the potential sostre of multi-family housing, even if the project uses less. Where the line falls for a small project.
The 600 m² threshold in Barcelona is measured on the plot, not the project: the 30% quota applies to a parcel where the plan allows more than 600 m² of sostre (buildable floor area) of multi-family housing, and if the project uses less, the 30% is still taken from the potential. The 30% quota is the obligation to give 30% of the sostre to publicly protected housing in a new build or a gran rehabilitación (major refurbishment) on suelo urbano consolidado (consolidated urban land). The rule sits in art. 285 ter of the Normas Urbanísticas of the PGM (Barcelona's metropolitan general plan) and has applied since 14.12.2018 (Ajuntament). The Supreme Court upheld it in judgment STS 110/2026 of 5.02.2026 (Ecija analysis). The general mechanics and protected-housing prices are covered in the article on the VPO quota and the house project; this one deals only with the threshold boundary.
How is the 600 m² threshold counted: by project or by plot?
By plot. That is what the explanatory presentation of 22.03.2019 on arts. 285 ter and 285 quater says, posted on the site of the Col·legi d'Arquitectes de Catalunya (COAC, the Catalan architects' association); the document names no author and does not replace the text of the Normas Urbanísticas. The Ajuntament's press release puts it more simply, "more than 600 m² of sostre built or under construction", so the difference in wording can only be settled by a written answer from the city. The document says: the quota applies to parcels with potential sostre of multi-family housing above 600 m². For a new build this is the potential under the plan; for a refurbishment, the built area (COAC). The project may take up 560 m², but if the plan gives the plot 640 m², the quota is counted on 640 m².
Three clarifications from the same source. A mezzanine in zones with street alignment is not counted. An extension without a gran rehabilitación falls under the quota only if the increase exceeds 600 m². For mixed-use projects the 30% is taken from the whole housing potential of the plot, and a whole building with another use falls outside the rule.
What counts as a gran rehabilitación?
The document lists three cases for art. 285 ter.3:
- Works across the whole building plus at least one of: an increase in sostre or volume, an increase in the number of dwellings, a structural change, a change of main use, a general redistribution. Repair and maintenance do not count.
- Replacement of the building, even if the facade or another element is kept.
- Works on the same building over five years, simultaneous or successive, costing 50% or more of the cost of a new building with the same sostre.
The third point matters for anyone who splits a villa into phases: three separate licences within five years are added together.
Which cases fall under the quota and which do not?
| Situation | 30% quota |
|---|---|
| New build, plot potential above 600 m² | Applies |
| Project uses less than the potential | Applies, the potential is the base |
| Extension without gran rehabilitación, increase up to 600 m² | Does not apply |
| Replacement of the building with the facade kept | Applies |
| Building with protection level A or B | Exception |
| Building with protection level C, type preserved, number of dwellings not increased | Exception |
The exceptions are in art. 285 ter.4 as summarised in the document; the list is not complete: there are others, for example parcels in polígonos de actuación urbanística (urban action areas) where building has not yet been carried out. A building's protection level is checked in the district catalogue; more in the article on protected villas.
What does this mean for a project of 3 to 8 houses and for a villa?
The open documents I checked do not address detached single-family villas (unifamiliar). The rule speaks of the potential for multi-family housing (plurifamiliar). So the number of houses in a project decides nothing. What decides is the plan zone and the sostre the plan gives the plot. For a villa being converted into several flats the question is different: with general works on the building, an increase in the number of dwellings puts it in gran rehabilitación. The answer for a plot comes from a written certificate from the Ajuntament and an opinion from an arquitecto (architect) before the offer (how to check the plan).
The quota applies in Barcelona. In Sitges and Castelldefels other Catalan rules apply, covered in the article on the project with an affordable-housing share in Sitges.
What does a mistake at the boundary cost?
Worked example, not a forecast. Assumptions: plot potential 640 m², project shown at 560 m², market price 7 000 €/m², floor areas treated as equal for simplicity. The price ceiling for protected housing under the general regime is 2 913,18 €/m² (Generalitat).
| Calculation base | 30% of the area | Loss against market |
|---|---|---|
| Project, 560 m² | 168 m² | 686 586 € |
| Potential, 640 m² | 192 m² | 784 669 € |
The difference between the two bases is about 98 000 €. That is the amount a calculation based on the project rather than the plan understates.
When this calculation does not work
It does not work for plots outside Barcelona or for purely non-residential buildings. It does not replace an arquitecto's opinion: the 2019 presentation is not an official act of the Ajuntament, and it does not address where the rule stops for detached unifamiliar villas. Nor does it say anything about the price of flats a year from now. Next step: put the quota in the calculator as a separate line and discuss the plot at a consultation; project formats are described on the development page.
Questions and answers
From what project size does the 30% quota apply in Barcelona?
To parcels where the plan allows more than 600 m² of multi-family housing sostre, for a new build or gran rehabilitación. A smaller project is not exempt if the plot's potential is above the threshold.
Is the 600 m² threshold counted by project or by plot?
By plot potential for a new build. If the project uses less, the 30% is still taken from the potential (document on the COAC site, 22.03.2019).
What is a gran rehabilitación?
Works across the whole building with an increase in sostre or in the number of dwellings, a structural or use change, or replacement of the building, or a series of works within five years costing 50% or more of a new building.
Which buildings are exempt from the quota?
Buildings with protection level A and B, and with level C those that keep their type without adding dwellings. The district catalogue is checked by the arquitecto.
Does the quota apply in Sitges?
No, it is a rule of the PGM of the city of Barcelona. In Sitges the Catalan rules on reserving protected housing in new sectors apply, which is a separate check.
