What is aluminosis, in plain English?
Aluminosis is the deterioration of concrete made with high-alumina cement («cemento aluminoso»), which Spain used widely in precast floor joists during the 1950s and 1960s. It was chosen not because it was cheap, it cost much more than ordinary Portland cement, but because it hardened fast and let factories turn out more joists.
The name was popularised by the press. The scientific idea was first defined in 1989 by the chemist Rafael Talero as three processes acting together in that concrete: conversion, carbonation and alkaline hydrolysis. According to the Barcelona association of building surveyors (CAATEEB), the material loses strength and becomes more porous during its first 7 to 10 years and then stops weakening on its own; what damages joists decades later is damp, which rusts the steel inside, exactly as it does in Portland-cement joists.
[1]Why does the word carry so much weight in Spain?
Because of one event. In November 1990 part of a building collapsed in Turó de la Peira, a Barcelona neighbourhood, and the word «aluminosis» became national news. A study by the Catalan construction institute ITeC then inspected about a thousand buildings in 300 municipalities across Catalonia.
Twenty years later, the CAATEEB wrote that the issue had become more social, economic and legal than technical: buildings with high-alumina cement were seen as sick and dangerous, banks gave them a much reduced value and judges treated the mere presence of the cement as a serious defect. That was written in 2010 and practices vary, but it explains why a seller may avoid the word and why you should ask about it directly, in writing.
[1]Which Spanish words will you hear about it?
The key terms are «cemento aluminoso» (high-alumina cement), «vigueta» (precast floor joist), «forjado» (floor structure, the slab between storeys), «armadura» (the steel reinforcement), «humedad» (damp) and «aluminosis» itself. Hearing them in a listing or a document is a reason to ask questions, not a verdict on the building.
Others you may meet: «bovedilla» (the infill block between joists), «patología» (defect, in the technical sense), «ensayo» or «test» (a laboratory or site test on a sample; the CAATEEB mentions an aluminous-cement test developed with the Polytechnic University of Catalonia), «refuerzo» (strengthening), «apuntalamiento» (propping), «derrama» (special levy to pay for works) and the building inspection, called ITE or IEE depending on the region. The professional who assesses a floor is usually an «arquitecto técnico» (building surveyor) or an architect.
[1]Does the year of construction tell you whether a building has it?
No, it only tells you whether to ask. The CAATEEB ties aluminosis to buildings from about 1950 to 1970, but in Catalonia alone more than a hundred joist makers used both high-alumina and Portland cement, so two buildings of the same year on the same street can have different joists.
The year of construction appears in the building's Catastro record, part of the non-protected data anyone can consult. If the flat falls in that period, go on to the building inspection, the minutes of the owners' meetings and any report on the floors. Only a professional visiting the building, and if needed taking samples from the joists, can say which cement is there and what state it is in.
[1][2]What should you ask before paying a deposit?
Ask the seller or the property manager for four things: the latest building inspection, the minutes of the last few owners' meetings, any study or test of the joists, and details of repairs or strengthening already done. Ask whether works or special levies on the floors have been approved and whether any flat has been propped.
If you do not speak Spanish, these sentences help: «¿El edificio tiene viguetas de cemento aluminoso?» (does the building have high-alumina cement joists?), «¿Se ha hecho algún estudio o ensayo de los forjados?» (has any study or test been done on the floors?), «¿Hay obras o derramas aprobadas?» (are works or special levies approved?). Ask for the answers in writing. Do this before the arras: under article 1454 of the Civil Code a buyer who pulls out afterwards loses the deposit.
[1][3]How do you read a building inspection that mentions the floors?
Look for the floors («forjados») and joists («viguetas») in the list of defects, and for words such as «fisuras» (cracks), «óxido» or «corrosión de armaduras» (rusting steel), «desprendimientos» (pieces falling away) and «humedades» (damp). Each defect usually carries a deadline; an urgent one on the floors deserves a professional opinion before you commit.
A favourable inspection means no defects were recorded on that date, not that the building has no high-alumina cement: inspectors look at what can be seen, and joists are usually hidden behind ceilings. An unfavourable one is not a verdict either. Read which element failed, how urgent it is and whether the owners' association has already approved the works; the answers change the price you should pay far more than the word «aluminosis» on its own.
[1]Which professional should you hire, and what should you ask?
An «arquitecto técnico» (building surveyor) or an architect with renovation experience. Ask them to look at the floors where damp does most harm, in bathrooms, kitchens, top-floor ceilings and next to drainpipes, and to tell you in writing whether openings or samples are needed.
If the cement is in doubt, they can order laboratory tests; the CAATEEB notes that the aluminous-cement test it launched with the Polytechnic University of Catalonia is still a support tool for professionals. Knowing the cement is not enough, though: to judge whether a joist floor is safe, the same article explains, it often has to be assessed as a whole, with analysis models or tests adapted to each case. Ask for a written report with the condition, the urgency and an indicative cost of any strengthening.
[1]How does HOUSINGFAX handle aluminosis?
Check 03 of the report answers «Is there a risk of aluminosis?» with a level in words: very low, low, moderate, high or very high. It starts from the Catastro year of construction and, where the regional register is integrated, from what the building inspection records about cracks, rust or falling concrete in floors and joists.
The report never says that a building has aluminosis; it says how likely high-alumina cement joists are and what to check next, in English, with each source and date. Start with the free report, which shows the check with your building's real data; the Essential report costs €11 and the Complete report, with the recorded building condition, €19: 22 checks on official sources, as a PDF within minutes, with a one-off payment and no account.
[2]What if the building does have high-alumina cement joists?
Then the question becomes their condition, not their existence. The CAATEEB insists that the type of cement is one more piece of information and never a defect by itself: joists kept dry can be in good condition, and joists of any cement can rust if damp gets in.
Ask a building surveyor to assess the floors, get a cost for any strengthening and decide with that figure: renegotiate the price, agree a written condition in the arras contract, or walk away. This article and the report do not replace an on-site technical inspection of the building; they tell you what to ask and whom to ask.
[1][3]Short answers
Is aluminosis common in Spain?
It concerns buildings with high-alumina cement joists, mostly from the 1950s and 1960s, and was most studied in Catalonia; many buildings of those years have Portland-cement joists instead.
Can I buy a flat in a building with high-alumina cement?
Yes. What matters is the condition of the joists, which a professional assesses, and whether repairs are needed and who pays for them.
Will a Spanish bank lend on such a building?
It depends on the bank and its valuation. In 2010 the CAATEEB reported that banks gave these buildings a much reduced value, so ask your bank early.
Does the Catastro say which cement a building has?
No. The Catastro record gives the year of construction and other non-protected data, not the materials of the floors.
Can the seller pay for a study of the floors?
You can propose it as part of the negotiation. Whatever you agree, who pays for the study and what happens if the result is bad, has to be written into the arras contract.
Does HOUSINGFAX tell me if the building has aluminosis?
No report can say that without an on-site inspection. HOUSINGFAX gives a level in words, from very low to very high, with its reasons and what to check next.
Sources you can consult
These references let you review the primary context. Their presence does not turn a source of context into a diagnosis.
- CAATEEB (Barcelona association of building surveyors) — «Aluminosi, problema resolt o conflicte latent?», L'Informatiu, September-October 2010 (in Catalan)Official source verified on 30 September 2026.
- Dirección General del Catastro (Spanish Cadastre) — FAQ on protected and non-protected data (in Spanish)Official source verified on 30 September 2026.
- BOE (Official State Gazette) — Spanish Civil Code, article 1454 (arras)Official source verified on 30 September 2026.
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