Could the building of the flat you like have aluminosis?

What aluminosis is

Aluminosis is the deterioration of concrete made with high-alumina cement, used in Spain mainly in precast floor joists between 1950 and 1970. According to the Barcelona association of building surveyors (CAATEEB), the material only loses strength in its first 7 to 10 years; after that, what damages the joists is damp, which rusts their steel.

High-alumina cement was patented in France in 1908, and in Spain Cementos Molins made it from 1928 under a Lafarge licence. Joist makers chose it because it hardened very fast: precast pieces could leave the mould sooner, which mattered in years of huge housing demand, even though it cost more than Portland cement.

The word “aluminosis” was popularised by the Spanish press. In 1989 the chemist Rafael Talero defined it as three processes acting together in high-alumina concrete: conversion (the material becomes more porous and loses strength in its first years), carbonation and alkaline hydrolysis. According to the Barcelona association of building surveyors, once that early phase is over the joists no longer lose strength on their own; what damages them later is damp, which rusts the steel.

Which buildings can have aluminosis?

Mostly blocks of flats built between 1950 and 1970 with floors of precast prestressed concrete joists. In Catalonia alone there were then more than a hundred joist makers, who used both high-alumina and Portland cement, according to the CAATEEB. So the year of construction is a clue, but it does not prove which joists a building has.

Mostly blocks of flats built between 1950 and 1970 with floors made of precast prestressed concrete joists. It also turns up in schools, industrial buildings and other structures of the period. Catalonia used it most, and the issue became national news in November 1990, when part of a building collapsed in the Barcelona district of Turó de la Peira.

Spain's 1973 concrete code (EH-73) did not ban it: it required a special study, case by case, to justify using it. So the year of construction is a useful clue but not proof. Two buildings of the same year on the same street can have different joists. The guide on construction years explains how to read that date.

Signs worth looking for

The usual signs are rust stains on the underside of the joists, cracks running along them, pieces of the concrete cover falling away and, in serious cases, exposed steel or a sagging ceiling. They tend to start where there is damp: bathrooms, kitchens, top-floor ceilings and next to drainpipes.

None of these signs is unique to high-alumina cement: a Portland-cement joist that stays wet for years rusts in the same way. A sign calls for a professional look, but it does not tell you which cement is there. The symptoms guide explains what to check on a viewing.

How is aluminosis confirmed?

Only a qualified professional in the building itself can confirm it: they inspect the floor structure and, if needed, take samples from the joists for laboratory tests such as porosity, chemical analysis or X-ray diffraction. INTEMAC engineers warn, in Informes de la Construcción (CSIC, 1992), that samples must come from the joists, not the columns.

Only a qualified professional visiting the building can confirm it. The work starts with a close visual inspection of the floor structure and, if needed, samples taken from the joists for laboratory tests such as porosity, chemical analysis, X-ray diffraction or thermogravimetric analysis. With those results they assess whether the floor is safe and whether to repair it, strengthen it or replace pieces.

Badly chosen samples mislead. The engineers of INTEMAC cite a Madrid building wrongly said to contain high-alumina cement on the basis of samples from columns cast on site, where that cement was hardly ever used. What matters is sampling the joists.

How HOUSINGFAX checks it: check 03

Check 03 of the report answers “Is there a risk of aluminosis?”. It starts from the year of construction published by the Catastro (the Spanish land registry of buildings) and, in the regions whose register is integrated, from what the building inspection (ITE or IEE) records about cracks, rust or falling concrete in floors and joists. The result is a level in words (very low, low, moderate, high or very high) with its reason and what to check next.

Start with the free report: it shows the check with your building's real data and the key information blurred. To see it in full, the essential report costs €11 and the complete report, which adds the recorded building condition, €19. That is 22 checks on official sources, as a PDF in a few minutes, with a single payment and no account. The report does not replace a technical inspection of the building.

Aluminosis in a purchase decision

The nota simple (Land Registry extract) tells you who owns the property; HOUSINGFAX tells you what state the building is in. If the flat dates from 1950 to 1970, before paying the deposit ask for the latest building inspection, recent minutes of the owners' association and any report on the floor structure or joist repairs. Ask too whether works or special levies have been approved.

High-alumina cement has weighed heavily in Spanish courts. The Barcelona association of building surveyors quotes Supreme Court rulings from 2005 and 2007 that treated it as a serious hidden defect even after repairs. Knowing before you sign lets you negotiate, commission a survey or walk away in time.

Thematic path: the four aluminosis guides

This page is the starting point. The guide on construction years explains which decades to check and why the date only points the way. The joists guide describes how a joist floor is built and how its cement is identified.

The building inspection guide covers what that document looks at and what it does not. The symptoms guide gathers the visible signs and where to look for them on a viewing.

Where to go next for your case

If you only have the address, start with the year: the free report gives it to you in minutes. If you already have the building inspection, look for the sections on structure and floors. If you have seen stains or cracks in a ceiling, read the symptoms guide and speak to a professional.

If at any point you see fallen concrete, a bulging ceiling or cracks that grow quickly, do not wait to find out which cement is there: tell the owners' association and a professional, and keep people away from that area.