Common defects by Lisbon building era
What each era tends to hide, and the check it usually calls for
Pre-1960
Pombalino and Gaioleiro Alfama, Mouraria, Graça, Baixa, Intendente
Critical risk

Timber rot in floor structures and partition walls

Rising damp in ground-floor and semi-basement units

Original lead plumbing and no earthing protection in electrical

Unpermitted marquises and enclosed extensions

Seismic vulnerability in buildings outside original Pombalino gaiola system

Usual next step Structural engineer's assessment
1960–1985
Betão (concrete transition era) Alvalade, Areeiro, Benfica, Campo de Ourique, Olivais
High risk

Spalling concrete and corroded reinforcement in balconies and stairwells

Original wiring with no earthing; undersized circuit breakers

Galvanised steel supply pipes corroding from inside

Gas installations pre-dating current DL 97/2017 framework

Asbestos in pipe insulation lagging (pre-1985 builds)

Usual next step Concrete, electrical and gas checks
1990–2010
Post-seismic code and Expo era Parque das Nações, Belém, Lumiar, Cascais corridor
Medium risk

Mixed plumbing materials at partial-renovation junctions

Inadequate mechanical ventilation below regulatory air-change rates

Façade micro-cracks and thermal bridge condensation at structural connections

Flat roof ponding on terraced apartments and penthouses

Usual next step Moisture and ventilation check
Renovated
Short-term rental conversions and cosmetic flips All postcodes, concentrated in tourist-demand areas
Variable risk

Cosmetic concealment of active damp behind fresh tiles or paint

Non-compliant electrical work from unlicensed contractors

Unpermitted layout changes concealed by the renovation

Original galvanised plumbing hidden under modern kitchen and bathroom finishes

Usual next step Look behind the new finishes
Sources: INE Censos 2021; DL 97/2017; RTIEBT · inspectos.pt