Concrete cancer in Spain: how to tell if your property has aluminosis, and what repairs cost

Let me start where nobody starts: the word "aluminosis" frightens people more than the reality usually warrants.

We've been walking into 1960s buildings in Valencia for years and we've seen the full range. Floor structures from that era in perfect condition, good for another fifty years. And floor structures I wasn't comfortable with until the area was propped. Same decade, same construction system, opposite outcomes.

So this article isn't here to scare you. It's here so you know which of those two you're dealing with, and so you can find out without spending a fortune doing it.

A note on terminology: in English we usually say concrete cancer, and in the UK the specific culprit is known as high alumina cement (HAC). In Spain this particular variant is called aluminosis. Related, not identical, and I explain the difference below.

What aluminosis is and why it matters

Aluminosis is the deterioration of concrete made with high alumina cement. It isn't damp, it isn't mould, it isn't an infestation, and it doesn't spread from one building to the next. It's chemistry: the material degrades on its own over time.

High alumina cement was used in Spain mainly between 1953 and 1973, almost always in pre-stressed floor joists. And it wasn't used out of carelessness: it set extremely fast, which meant striking formwork sooner and building far quicker. In the middle of a housing boom, that was gold. Nobody yet knew what would happen thirty years later.

Why high alumina cement degrades

There's a process called conversion. The internal crystalline structure of the concrete changes over the years, becomes more porous and loses strength. So far, bad but manageable. This alone doesn't bring a building down.

The real damage comes next. Porous concrete lets moisture and air reach the steel inside. The steel corrodes, rust takes up more volume than the original metal, and it blows the concrete apart from within. That's when you get spalling and genuine loss of load-bearing capacity.

And here's the point that in my opinion is badly under-reported: without moisture, this progresses far more slowly. Damp and heat are the accelerant. That's why the first thing I look for when I walk into a building isn't the joists — it's where the water is.

Why it's particularly serious

Four reasons, none of them dramatic.

First, it happens inside. By the time you see it, it's been going for years. Everything else that fails in a house announces itself: damp stains, a window sticks, a boiler rattles. This does nothing until it does a great deal.

Second, it's structural. Not an ugly finish, but the thing holding up your neighbour's floor. Different order of magnitude.

Third, it feeds itself. More porosity, more moisture. More moisture, more corrosion. More corrosion, more cracking. And through those cracks comes more water. Once started, the process doesn't settle down on its own.

Fourth, and nobody tells you this until you live it: the trouble doesn't end with the building work. It affects valuation, whether you get a mortgage, whether you can sell, and your liability towards a buyer.

For the record, the use of joists with high alumina cement content was banned in Spain in 1977. What put the issue on the public map was the collapse of a building in the Turó de la Peira district of Barcelona in 1990.

Which properties in Spain are at risk

Construction period

The profile is fairly clear: buildings put up between 1950 and 1977, concentrated in the sixties and early seventies, with one-way floor slabs built from precast joists — the system used almost universally at the time. In Valencia and the surrounding area that covers a large share of the neighbourhoods that grew in those decades, and also many villas and detached properties from the first wave of coastal urbanisations.

Now, the thing I think needs saying plainly: having high alumina cement is not the same as having a problem. They're two different things and they get conflated constantly.

We've opened up a floor expecting the worst and found it perfectly sound. And we've had the reverse in a building that looked immaculate from outside. The difference? Almost always water. If there's been a chronic leak in that area for twenty years, that's where your problem is. If the structure has stayed dry, it's usually fine.

Which is why the hotspots are always the same: bathrooms, kitchens, roofs, terraces, cantilevers and garages. If your building has damp that nobody has dealt with for years, and the floor structure is from that era, you know where to start looking.

How much risk your building carries, by year

If it's pre-1950, you can relax as far as aluminosis goes: other systems were used. Don't get complacent though, because these buildings have their own issues — timber beams, woodworm, termites, rising damp.

Between 1950 and 1959 risk is low to moderate. The material existed but hadn't become standard. I'd look into it if there are visible symptoms or a history of leaks.

Between 1960 and 1977 is where the bulk of the problem sits. My advice here is blunt: have it checked even if you can't see anything wrong, particularly if the building has ever had leaks. If you're in this band and that floor structure has never been tested, this article is for you.

Between 1978 and 1990 it was already banned, so you can forget about aluminosis. What is worth watching in these buildings is carbonation of the concrete and corrosion of reinforcement — a different thing, explained below.

From 1990 onwards, don't give it a thought.

One detail that looks trivial and isn't: the date that matters is when the floor structure was built, not the date on the deeds or the cadastre. Those can differ by years. And in this band, those years change everything.

How to tell whether your Spanish property needs aluminosis repair

Visible signs you can look for yourself

A warning first: none of these confirms anything on its own. But if you spot one, it's worth having someone look.

The most characteristic is colour. A joist with aluminosis tends towards brown, ochre or orange rather than the usual grey of concrete. Then there are longitudinal cracks on the underside of the joist, following the line of the reinforcement, and rust staining or those brown streaks on ceilings. Further along you get spalling concrete exposing the steel, and deflection: ceilings or floors visibly sagging.

And two indirect clues almost everyone misses: cracks in a partition wall directly beneath a joist, and doors that suddenly stop closing properly for no obvious reason. Either can be telling you the floor structure has moved.

Where can you look yourself? The garage and storerooms. That's where the structure is usually exposed, with no suspended ceiling in the way. Five minutes with a torch will tell you more than you'd expect.

Professional testing

What you can see points the way. What diagnoses is testing. Four steps, no more.

First, the preliminary technical inspection. A surveyor looks wherever access allows, or opens a small inspection hole, and decides where testing actually makes sense. Sounds minor, but it's what stops you wasting money testing the wrong spot.

Second, the chemical test for high alumina cement. A sample is taken and treated with a reagent that detects aluminates. It answers the binary question: is it there or not? Quick and cheap compared with everything else.

Third, core samples and laboratory analysis. Cores are extracted from the structure and assessed for degree of conversion, porosity, actual strength and the condition of the steel. This is the step that turns "you have aluminosis" into "you have aluminosis to this degree, and here's what that means". The difference is enormous.

Fourth, the structural report with a proposed course of action. That's what you actually walk away with: what gets replaced, what gets strengthened, what gets monitored, and in what order.

My unfiltered opinion: without steps two and three you don't have a diagnosis, you have a suspicion. And if someone quotes you for repairs before testing, I'd be wary. Not because it's bad practice, but because it is literally impossible to know what fixing something costs without first knowing what's broken.

Aluminosis versus carbonation

These two get confused constantly, including by people in the trade, and they are not the same.

Carbonation happens to any concrete, whatever cement it was made with. CO₂ from the air penetrates, reduces the material's alkalinity, and the steel loses the natural chemical protection that keeps it from corroding. That's normal ageing.

Aluminosis is specific to concrete made with high alumina cement and concerns conversion of the material itself.

Why the distinction matters to you: you can have a carbonated slab with no aluminosis whatsoever. And a slab with aluminosis carbonates far faster, precisely because it's more porous. Different diagnosis, different solution, different price. If you're handed a report that doesn't separate the two, you haven't been handed a report.

What to do if your building might have aluminosis

Check the building's ITE

Start here, it's free. The ITE is Spain's mandatory periodic building inspection. If your building has already had one, the report states the structural condition found and the defects on record. Very often the first warning and the recommendation to test the floor structure come from exactly there.

Ask the administrator or the owners' association for it before you hire anyone. And check whether it's still current, because whether it's required and how often depends on the age of the building and the municipality.

Obvious, perhaps, but you'd be surprised how many people call us for testing while there's a report in a drawer that already flagged the problem.

Commission a structural report

If the ITE flags something, if you can see symptoms, or simply if your building dates from 1960 to 1977, the next step is the structural report with testing.

That document gives you leverage. With it you can go to the owners' meeting and turn the conversation from opinions into facts. You can request quotes that are genuinely comparable. You can apply for grants. And if you're buying or selling, you negotiate with data instead of fear.

Weigh up the repair options

With the report in front of you, options run from light to heavy.

Always first, and I'll keep repeating it: stop the water. Sometimes it's the cheapest item of the lot and the one that changes the most. If water keeps coming in through the roof, the terrace, the façade or a broken downpipe, any repair underneath will simply degrade again. That's throwing money away with style.

For light, localised damage there's repair and passivation of the reinforcement: cut out the damaged concrete, treat the steel and rebuild the section with repair mortars.

A step up is strengthening the joists, keeping the existing elements and restoring their capacity. That can be done with steel sections, with connectors, or with carbon fibre laminates bonded to the element — the latter has become fairly common because it adds almost no weight and goes in quickly.

When degradation is advanced you're into joist replacement: prop the area, remove the affected elements and install new ones. And if almost everything is affected, rebuilding the whole floor structure ends up cheaper than repairing piece by piece.

One piece of advice we always give on villas and detached houses: if the job involves propping, breaking out and lifting floors anyway, stop and think before you start. Doing services, layout and finishes at the same time costs a fraction of doing them as two separate projects. And you won't want to live through this again in five years.

The process: how an aluminosis repair in Valencia actually runs

Here's how we do it, so you know what to expect and in what order.

Site visit and initial inspection. We come out, request the ITE if one exists, and examine the floor structure wherever it's accessible — garage, storerooms, above suspended ceilings. We're looking for two things: which areas look worst, and where water is getting in. This visit produces a judgement, not a quote.

Testing and core sampling. Chemical test to confirm whether high alumina cement is present, and cores taken at the points the surveyor specifies. Samples go to the laboratory.

Structural report. With results in hand: which elements are affected, to what degree, what's urgent, what can wait, and what we propose for each. That document is yours and remains useful even if someone else ends up doing the work.

Fixed quote, broken down by phase. With the scope now defined. We always separate what's essential from what's advisable, so you decide, rather than facing a single figure you can't break down.

Propping and safety measures. Before anything is broken out, the area is propped, cordoned off and signed. If the property or garage needs to stay in use during the works, that's planned here.

Eliminating the cause. Roof, terrace, façade or downpipe — whatever was letting water in. This first, then the structure. Never the other way round.

Execution. Repair and passivation, strengthening or replacement, as set out in the report and in the order of priority it established.

Reinstatement and finishes. Everything goes back: suspended ceilings, flooring, decoration. If you've chosen to fold a renovation into the job, this is where the two converge.

Final certificate and documentation. You get the complete file — report, test results, process photographs and the certificate for the intervention. Keep it: you'll need it for the owners' association, for the next ITE, and on the day you sell.

What aluminosis repair costs

Honestly: it depends on scope, and anyone giving you a fixed figure without having seen the structure is selling, not pricing.

That said, I dislike articles that hide behind "it depends" and never commit to a number. So here are the figures, so you at least know whether you're in four digits or five.

Indicative prices

Start with diagnosis, which is what you pay for first and is by far the cheapest part. The chemical aluminosis test from €90. If cores need to go to a laboratory, from €250. And the full structural report, including recommendations, from €450.

Put another way: for less than the cost of replacing a blind, you stop guessing. And it's the best investment in the whole process, because it's what stops you spending twenty thousand where five were needed, or the reverse.

On the works side, strengthening beams and joists starts from €60 per linear metre, the standard market reference. Concretely: strengthening two five-metre beams with carbon fibre laminate comes in around €500.

Per unit: repair and passivation of a joist from €150, strengthening from €250, replacement from €300. If the whole floor structure has to be rebuilt, from €120 per square metre.

And at whole-intervention scale: dealing with the affected beams in a single property starts from €900, a complete ceiling from €4,000, and a building-wide aluminosis repair typically runs between €4,000 and €20,000, averaging around €8,000.

To state the obvious again: these are starting prices and market references, not a quote. Your case might sit at the minimum or well above the maximum, and you only find out after testing.

Who pays

This is where sparks fly at Spanish owners' meetings.

The floor structure is a structural element and therefore common property. Repair falls to the owners' association, normally through a special levy, even though the damage only shows inside one apartment.

And this catches people out in both directions: the owner who had resigned himself to paying alone, and the neighbour on the third floor who says it doesn't concern him because his ceiling is fine. Taking a technical report to the meeting saves months of argument and a fair amount of bad feeling.

On insurance, don't get your hopes up. Home and community policies generally exclude damage from inherent material defect and wear, so the norm is that you're not covered. And the ten-year structural warranty isn't worth mentioning: these buildings are long past ten years.

Available grants

You need to separate what exists from what's currently open, because they aren't the same and confusing them is expensive.

What exists is a framework of building renovation grants funded by European money and administered here by the Generalitat Valenciana. The last major round, covering 2024-2026, mobilised over €73 million across several programmes: building-level renovation, energy efficiency improvements in individual homes, preparation of projects and the building logbook, and a personal allowance for vulnerable households in a building undergoing renovation. That round closed on 27 February 2026.

So the first thing to do is check what's open today, on the Generalitat Valenciana's electronic portal. Don't trust any dated article — this one included — to assume a deadline is still live.

Now the important part: how this connects with aluminosis. These grants target energy efficiency, not structural repair. Replacing joists doesn't qualify on its own. But here's the point almost nobody exploits: if stopping the damp means working on the roof or the façade — and in most cases that's exactly what's required — that portion of the work usually does qualify, because it's an improvement to the thermal envelope.

Translated: structure the job properly and the part you were going to carry out anyway can come in considerably cheaper. And sequence matters here, because these schemes normally require a prior technical report and an application before work starts. Do first, ask later, and you're out.

Why this belongs with a specialist

After a fair few of these, I hold a firm view: with aluminosis there are two ways to waste money.

One is repairing without diagnosing. You end up breaking out where it wasn't needed and leaving untouched precisely what was compromised. The other is diagnosing beautifully and not eliminating the cause. That one's worse, because you spend a fortune on a flawless repair that degrades again within a few years while the roof leak sits exactly where it always did.

What makes the difference, in our experience, is having structure and envelope in the same hands. We do both: strengthening and replacing floor structures, and also the roof, façade and waterproofing that have to be resolved so the problem doesn't return. When each part sits with a different firm, everyone answers for their own piece and the underlying problem ends up split across two invoices and nobody's responsibility.

We work across Valencia, Alicante and the Marina Alta, on detached houses, villas and owners' associations. And one thing we always do: the report we work from is yours, whether you award us the job or not.

Frequently asked questions

Can a bank refuse me a mortgage because of aluminosis?

Yes, it can refuse or impose conditions. An unrepaired structural defect lowers the valuation and raises the lender's risk.

What we see most: either they require the repair first, or they approve considerably less than you expected.

Does aluminosis affect every flat in the building equally?

No. Even where high alumina cement runs through the whole structure, deterioration depends on the moisture and heat in each area.

Ground floors, top floors under the roof and any flat that has had leaks tend to be worse. A dry mid-level flat can be perfectly sound.

Can you live in a property with aluminosis?

In most cases yes, as long as the structure retains sufficient capacity. Only testing can confirm that.

If you can see sagging ceilings, spalling concrete or exposed steel, that won't wait: call a surveyor today.

Can aluminosis be fixed permanently?

Yes. Replacing affected elements is permanent, and strengthening with a dry structure lasts for decades.

What doesn't reverse is conversion of the cement. But that doesn't mean you're living on a time bomb.

Is the seller obliged to disclose aluminosis?

Yes. Concealing a known structural defect can be claimed as a hidden defect, so the safe course is to hand over the report.

And if you're buying: sixties or seventies building, ask for the ITE before you sign. One phone call can save you a five-figure problem.

Unsure about your floor structure, or does your owners' association need to make a decision and nobody knows where to start? Get in touch. We'll come out, take a look and tell you what's there — no drama and no glossing over it. Aluminosis test from €90, full structural report from €450. We work in Valencia, Alicante and the Marina Alta, and you can deal with us in English throughout.