Aluminosis is probably the most feared "ghost" when buying old flats in Barcelona, and with historical reason: the collapse of a building in Turó de la Peira in 1990 put the issue on the front page. The good news is that not every building of the period suffers from it, and today it can be diagnosed and repaired. The key is to know whether your building is in the risk window and check it before signing.
What aluminosis is
Aluminosis is the degradation of concrete made with aluminous cement (also called calcium aluminate cement). This cement was used because it set very fast and provided high initial strength, ideal for producing prefabricated joists for slabs.
Over time and in the presence of moisture and heat, the material undergoes a chemical process (the "conversion") that increases its porosity and reduces its strength. The concrete becomes more brittle and, above all, lets water and oxygen reach the steel reinforcement, which oxidizes and swells, worsening the structural damage.
Which buildings are at risk (1950–1977)
Aluminous cement was used in residential construction roughly between 1950 and 1977. Spain restricted its structural use in the late 1970s. The risk therefore concentrates on buildings from that period, widely present in Barcelona neighborhoods and metropolitan area municipalities that grew strongly in those decades.
If the building was built between 1950 and 1977, it enters the risk window and should be reviewed. Outside that range, the probability of aluminosis is very low. The year of construction is in the Cadastre and you can check it for free.
Important: being within the period does not mean having aluminosis. Many buildings of those years used regular Portland cement, or their aluminous cement joists are in a dry environment and well preserved. The period only marks when the problem must be ruled out, not a sentence.
Visible warning signs
A technician is the one who confirms it, but there are signs you can observe yourself during a visit, especially in damp areas (bathrooms, kitchens, balconies, ground-floor ceilings and roofs):
- Abnormal concrete color: affected joists usually have a reddish-brown or chocolate tone instead of the usual gray.
- Longitudinal cracks on the joists, parallel to the reinforcement.
- Rust stains and exposed reinforcement.
- Deflections or buckling: ceilings or slabs that bow or sag.
- Spalling that exposes the porous interior of the concrete.
- Persistent damp in the structure, which accelerates the process.
Many flats have suspended ceilings that hide the joists. The absence of visible symptoms doesn't rule out aluminosis: the real structure needs to be inspected, not the finish.
How it's confirmed: the diagnosis
Definitive confirmation is technical and has two levels:
- Visual inspection by an architect or quantity surveyor, who accesses the structure (removes suspended ceilings at specific points) and assesses symptoms.
- Lab analysis: a concrete sample is extracted from a joist and chemically analyzed to confirm whether it contains aluminous cement and its degree of conversion. It's the conclusive test.
If you buy in a building from the risk period, the reasonable thing is to condition the purchase on a structural report, or at least reserve the right to do one before the deposit agreement.
Repair and cost
Aluminosis can be fixed, but it's not cheap. Typical interventions:
- Reinforcement of affected joists (metal profiles, reinforcements).
- Replacement of the joists or the complete slab in severe cases.
- Removing the causes: fixing damp and leaks.
The cost depends on the extent of the damage and how many floors it affects. It's a community work when it affects the common structure, so it's split via building levy among the neighbors. It can range from spot repairs to renovations of tens of thousands of euros per dwelling in the worst scenarios.
How it affects your purchase, mortgage and insurance
Aluminosis isn't just a physical risk; it has economic and financial impact:
- Mortgage: if the appraisal detects unrepaired aluminosis, the bank may reduce the valuation or deny financing.
- Insurance: some insurers exclude damage from pre-existing aluminosis.
- Price: a building with aluminosis (or in the process of repair, with a levy) must reflect it in the price. It's a strong negotiation argument.
- Appreciation: once repaired and certified, the building recovers value; unrepaired, it loses value.
If the building is from 1950–1977: (1) the ITE report and whether it mentions the structure, (2) whether an aluminosis study has ever been done and its result, (3) meeting minutes with structural works or levies, and (4) ideally, your own structural report before the deposit agreement.
Aluminosis and ITE
The ITE (technical building inspection), mandatory in Catalonia from 45 years, is the first safety net: a well-done inspection in a building from the risk period should assess the structure. But the ITE is a general review; to confirm or rule out aluminosis the specific lab analysis is required. One doesn't replace the other.
Is the building you like in the risk window?
Type the address in our analyzer and, for free, we tell you the year of construction according to the Cadastre, whether it falls in the aluminosis range (1950–1977), whether the ITE is mandatory and what else to check. No registration.
Analyze my flat →Frequently asked questions
What years does the aluminosis risk cover?
Aluminous cement was used roughly between 1950 and 1977. Buildings from that period are the ones worth reviewing; outside it, the risk is very low.
How do I find out a building's year of construction?
It's in the Cadastre and free. You can see it instantly with our flat analyzer, which also tells you whether it falls in the risk period.
Does a building of that era surely have aluminosis?
Not necessarily. Being in the period only indicates that you have to rule it out. Many buildings from the 50s–70s used normal cement or have joists in good condition. Only the analysis confirms it.
Can you get a mortgage for a flat with aluminosis?
It depends. If repaired and certified, usually yes. If unrepaired and the appraisal detects it, the bank may lower the valuation or deny the loan. Best to clarify before the deposit agreement.
Who pays for the aluminosis repair?
Since it affects the building's common structure, it's a work of the owners' community and is split via building levy. If you buy, you inherit the levies approved after the purchase.
Does the ITE detect aluminosis?
The ITE assesses the overall condition and may raise the suspicion, but confirmation requires a lab analysis of a concrete sample. They are complementary.
Editorial notice. This guide is informational and based on general knowledge of aluminous cement and its pathology known on the update date (2026). It doesn't replace the opinion of a qualified technician or a lab analysis. Listing Barcelona is an editorial, independent platform. If you suspect aluminosis, consult a registered architect or quantity surveyor.