Insulating a condominium building: a practical guide

Insulating a condominium building in Portugal: a practical guide for building managers

In a building divided into units (propriedade horizontal), insulating the common parts (façade, outside walls, roof) is a decision for the owners' meeting (assembleia de condóminos). The majority you need depends on the type of work: conservation work is approved by a simple majority; an innovation, or work that changes the look of the façade such as capoto, needs two thirds of the building's total value. This guide explains the rules, the costs and the steps, from the decision to the work itself.

EnergyEase supports building managers and works committees in Lisbon, Cascais, Oeiras, Sintra and Setúbal: technical assessment, a proposal for the meeting and a cost comparison between techniques.

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Which insulation works are possible in a condominium?

• Blown-in insulation in cavity walls: small holes, sealed at the end; the look of the façade does not change.
• Insulating the roof or the shared attic: a common part, decided at the owners' meeting.
• Capoto (ETICS) on the outside façade: it changes the look of the building, so it needs approval from the meeting by two thirds of the building's total value.
• Insulating floors above garages or basements: in common areas or in specific units.
• False ceiling with insulation on the top floor: can be done unit by unit.

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What majority does the owners' meeting need?

The rules are in the Portuguese Civil Code (Código Civil), in the articles on buildings divided into units (article 1414 onwards). In short:

• Conservation work (repairing and maintaining what is there): a simple majority of the votes, counted by the value of the units (article 1432).
• Innovations (work that adds something new to the common parts): a majority of the owners representing two thirds of the building's total value (article 1425).
• Work that changes the architectural line or the look of the building, such as capoto: approval from the meeting by a majority representing two thirds of the building's total value (article 1422, no. 3).
• Essential and urgent repairs to the common parts: they can go ahead without waiting for a meeting; if the building manager is absent or unable to act, any owner can have them done (article 1427).

Whether insulation counts as conservation or as an innovation depends on the work and on the state of the building, and the law does not decide it case by case. Blown-in insulation does not change the look of the façade, but it can still be treated as an innovation. If in doubt, prepare the vote for the stricter majority, or check with the building manager or a lawyer. At the visit we explain what each technique involves, so the proposal is clear.

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How much does it cost to insulate a condominium building?

It depends on the size of the building and the technique. Indicative figures, VAT included, for a typical building in Lisbon:

• Building with 8 units and 400 m² of façade:
  • Blown-in insulation: 400 × €30/m² = €12,000 (about €1,500 per unit)
  • Capoto (ETICS): 400 × €80/m² = €32,000 (about €4,000 per unit)
• Building with 16 units and 800 m² of façade:
  • Blown-in insulation: 800 × €30/m² = €24,000 (about €1,500 per unit)
  • Capoto (ETICS): 800 × €80/m² = €64,000 (about €4,000 per unit)

The difference is large: on the same building, blown-in insulation costs about half as much as capoto, or less. Capoto, on the other hand, also covers pillars, beams and slab edges. See our full price guide.

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What grants are there for condominiums?

Grants open and close during the year. In September 2026 we know of no national programme currently open; in Amadora the municipal REABILITA programme is running. In general, grants fall into three groups:

• National programmes: run mainly through the Fundo Ambiental (Environmental Fund). Some are aimed at municipalities, charities (IPSS) and residents' associations rather than directly at private condominiums.
• Municipal programmes: some councils have their own grants, with rules set locally.
• Grants for individual owners: some programmes are aimed at households and can be used by each owner for their own unit.

See our guide to grants or ask us for the current situation.

Preparing the owners' meeting: step by step for the building manager

1. Technical diagnosis: ask for a free technical visit to check the type of walls, whether there is a cavity, and the state of the façade and the roof.
2. Comparable quotes: ideally 2 or 3, stating the technique, the material and the timeframe.
3. Notice of the meeting: at least 10 days in advance (article 1432), with a clear item on the agenda, for example "Approval of thermal insulation works on the building".
4. Documents for the owners:
   • a comparison of techniques (blown-in or capoto);
   • the estimated cost per unit, based on each unit's share of the building (permilagem);
   • what changes in daily life during the works;
   • the timeframe.
5. Discussion and vote: benefits, costs and the impact of the works, with answers to technical questions.
6. Minutes: record the decision, the majority obtained, the amount approved and the company chosen.
7. Grant application, if a programme is open: check whether it has to be made before the works start.
8. Works: let the owners know in advance. With blown-in insulation, the work usually takes 1 to 3 days per building.

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How to answer the most common objections

• "The works are too invasive." Blown-in insulation needs only small holes, sealed at the end, and people stay in their homes during the work.
• "I don't feel cold or hot." Show the building's energy certificate and the signs that are already there: cold walls, condensation, mould in the corners.
• "It will ruin the façade." With blown-in insulation, once the holes are sealed, the façade looks as it did. With capoto the façade changes: show examples of finished projects.
• "Who guarantees the quality?" A company with a construction licence (alvará), civil liability insurance, the legal guarantee on the work and technical data sheets for the materials.

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What is specific to the Lisbon area

In Lisbon's historic districts (Alfama, Mouraria, Bairro Alto, Baixa) planning rules often rule out capoto. Old buildings there usually have stone masonry walls without a cavity, so blown-in insulation does not apply either. There, the answer is the roof and insulating each unit from the inside (an insulated lining wall). The same can apply in protected areas of Sintra and Cascais.

In newer buildings (after 2006) in the Lisbon Metropolitan Area, cavity walls are common, but many already have insulation. At the visit we check with a camera whether there is still room to blow insulation in. See examples in our project portfolio.