What is an extension or loft worth in Cascais?
These are works to a house
Extensions, lofts, garage conversions and annexes assume a property you can build on or into — a house, bungalow or cottage with its own footprint. None of them applies to a flat or an apartment, where the floor area is fixed and the fabric is shared. The £/m² basis below is the whole island's stock, flats included.
Space in Cascais, Lisbon, Portugal is asking about €11,139 per m² (30 listings there publish a floor area). Build costs below are published per-m² ranges. Neither is a quote, and value added is never the whole story — the first extension on a small house adds more than the third on a large one.
| Work | Size assumed | Likely build cost | Value that space would ask | Difference |
|---|---|---|---|---|
| Demolish and rebuild | 140 m² | €392,000 | €1,559,460 | +€1,167,460 |
| Two-storey extension | 45 m² | €99,000 | €501,255 | +€402,255 |
| Single-storey extension | 25 m² | €60,000 | €278,475 | +€218,475 |
| Annexe or outbuilding converted space, valued at 75% of the local rate |
30 m² | €63,000 | €250,628 | +€187,628 |
| Loft conversion converted space, valued at 85% of the local rate |
22 m² | €38,500 | €208,299 | +€169,799 |
| Garage conversion converted space, valued at 70% of the local rate |
16 m² | €20,000 | €124,757 | +€104,757 |
What this is doing, exactly
- Value is the local asking rate per m² multiplied by the space added — discounted for conversions, where a converted garage or loft does not fetch what new build does.
- Cost is a published per-m² range for that kind of work. It excludes professional fees, planning fees, VAT or GST, and anything the drawings show that the description does not.
- Granted is this island's own record for that kind of application. It is not a prediction about yours.
- A positive difference is not a profit. It ignores the cost of money, the months of disruption, and the fact that a buyer pays for a house, not a spreadsheet.
Monte Estoril, Estoril, Lisbon, Portugal €15,179/m²Cascais e Estoril (Cascais) €13,176/m²Estoril €12,963/m²Centro Historico, Cascais, Lisbon, Portu €12,192/m²Cascais, Lisbon, Portugal €11,139/m²Estoril, Lisbon, Portugal €10,923/m²Quinta da Marinha, Cascais, Lisbon, Port €9,343/m²Carcavelos e Parede €8,803/m²Cascais e Estoril €8,104/m²Alcabideche €7,238/m²