Hidden defects in older buildings, such as high-alumina cement (aluminosis)

Key rules

• Aluminosis: Buildings from about 1950 to 1975 carry the most risk, and only an architect's inspection plus laboratory tests can confirm it.
• Asbestos: Intact asbestos can stay, but only registered companies may remove it.
• Lead pipes: The owner or community of owners must replace lead pipes inside the building if lead is found.
• Old wiring: An old installation is acceptable only while safe, and a new boletín is often needed for a new supply contract.

The five red flags

If the building is old, treat these five as serious until a specialist says otherwise: aluminosis, fibre-cement asbestos, lead pipes, old wiring and structural cracks. None is a reason to panic. Each is a reason to get an expert opinion before you commit money.

Aluminosis and structural cracks

Aluminosis is the slow weakening of high-alumina cement (cemento aluminoso). Warm, humid conditions make it lose strength. It was used in structural parts, mainly prestressed beams and joists, from about the 1950s until it was banned for structural use in Spain in 1983.

Take extra care with buildings from about 1950 to 1975, especially on the coast or in humid areas.

Warning signs are cracks, rust stains and damp on beams, joists and ceilings. Any wide or growing crack in a wall, beam or ceiling also needs a specialist, whatever the building's age.

The usual route is:

1. An architect or technical architect inspects the structure by eye.
2. If they suspect aluminosis, core samples go to an accredited laboratory. The lab measures the alumina content and how far the cement has deteriorated.
3. Repairs range from reinforcing the structure to replacing the affected parts.

The decision block below helps you choose how far to go.

Asbestos in fibre-cement roofs and tanks

Asbestos was banned in Spain in December 2002. Older fibre-cement items, such as uralita roofs and water tanks, may still be in homes built before then.

• Asbestos that is intact does not have to be removed. The owner must keep it in good condition.
• Only companies registered for asbestos work may remove it. They need a work plan approved by the labour authority, and the waste must go to authorised disposal.
• Never drill, cut, break or scrub it yourself.
• Local authorities are building inventories of buildings with asbestos and can set removal timetables. Ask your town hall what applies locally.
• A seller has no general duty to announce asbestos, but must not hide a defect they know about.

Lead pipes

Lead pipes were common in Spanish homes until the 1970s, and sometimes later. Look for old grey, soft metal pipes where water enters the home, and ask the seller or landlord about the plumbing.

The legal limit for lead in drinking water is 10 micrograms per litre now. It falls to 5 micrograms per litre from 1 January 2036.

Who is responsible depends on where the pipe is:

• The water company looks after the public network up to the meter or connection.
• The building owner, or the community of owners, looks after the internal pipes. If lead is found, the owner must replace the affected pipes.

You can ask the water supplier or an accredited laboratory for a water analysis.

Old wiring

Old wiring does not have to be upgraded just because the rules changed. The current rules apply in full to new installations and major reforms. An old installation is acceptable only while it stays safe.

Typical risks are:

• no earth connection
• no residual-current devices (the switches that cut power on a leak)
• cables that are too thin
• an old fuse box

You will often need a new electrical installation certificate (boletín or CIE) to sign a new supply contract or change the power. This is common when the installation is more than 20 years old. Rules on renewing the boletín vary by region, so ask the electrician or your regional office.

Periodic inspections are mandatory for some buildings, such as the common areas of large buildings, but not generally for individual homes.

Partial or full rewiring is often needed in old homes. It costs several thousand euros, depending on size and region. Get a quote from an authorised electrician before you agree a price.

Before you commit

Use the checklist below on viewings. Bring in an architect for structure and an electrician for wiring before you sign or pay anything you cannot recover. If you find serious defects after moving in, see the section below on what to do.

Choosing between options

What should you do about a possible aluminosis problem?

• Go ahead without further tests: The building was built after 1983, when high-alumina cement was banned for structural use, and you see no cracks, rust stains or damp.

• Get an architect's visual inspection first: The building dates from about 1950 to 1975, or you see cracking, rust stains or damp.

• Order laboratory tests on core samples: The architect finds signs and wants to measure the alumina content and how far the cement has deteriorated.

Start with the building's age. Anything from about 1950 to 1975 needs an architect's inspection, and lab tests follow only if the architect sees signs. The test results decide between reinforcement and replacing the affected elements.

Documents you need

• New electrical installation certificate (boletín or CIE), issued by an authorised electrician. You need it for a new supply contract or a change of power in many cases, and it is often needed when the installation is more than 20 years old.

Checklist

• Find out the year the building was built, and take extra care if it dates from about 1950 to 1975, especially on the coast or in a humid area.

• Ask an architect or technical architect to inspect the structure if you see any of these signs.

• Ask for core samples to be tested in an accredited laboratory if the architect suspects high-alumina cement.

• Ask the seller for the electrical installation certificate and check whether the installation is more than 20 years old.

• Have an electrician check for an earth connection, residual-current devices, cable size and the state of the fuse box.

What if you find serious defects after moving in?

Do these things first, in this order

Make the home safe, then document the problem before anything is repaired. Stop any further damage, such as shutting off water or power to a faulty circuit. Keep every receipt. Take dated photos and video of the defect, and film it again as it gets worse. Keep the contract, the listing, and any messages that described the home's condition.

Tell the right person in writing. Use a method that proves you sent it: a burofax (a registered letter that records its content), an email with delivery confirmation, or a notary. WhatsApp messages help as backup but should not be your only notice.

• If you bought: tell the seller. A buyer's claim for hidden defects expires 6 months from delivery, so act quickly and get legal advice. For a new-build, also tell the developer and its insurer. Guarantee periods of 1, 3 and 10 years apply depending on the type of defect.
• If you rent: tell the landlord, and the agency if there is one, and ask for a repair. The landlord must repair defects that are not your fault. For urgent repairs, you can arrange them and claim the cost back. Keep the invoices. If the landlord ignores you, try mediation first, then court.
• If the problem affects shared parts such as the roof, facade or pipes, also tell the community administrator.

Get a written technical report. Ask an architect or an aparejador (a building technician) to state the cause, how long the defect has existed, and what the repair will cost. This report is your strongest evidence. A colegio's stamp on it adds weight.

Then build your case

• Get quotes for the permanent repair.
• Ask neighbours, the administrator or tradespeople for short written statements.
• If the evidence may disappear, for example while a leak is being fixed, ask a notary to record the condition in an acta notarial. A lawyer can also ask a court to take expert evidence early.
• Check your home insurance and tell the insurer promptly, as it may cover the damage.

When to see a lawyer

Book a lawyer (abogado) as soon as the report is back, and before that if you bought, because the 6 months run from delivery. Time limits differ by type of claim, so the lawyer should confirm which one applies to you.

Frequently asked questions

Do I have to remove an old uralita roof before I buy or move in?

No, an intact fibre-cement (uralita) roof does not have to be removed, but the owner must keep it in good condition. If you do remove it, only a company registered for asbestos work may do it, after a work plan approved by the labour authority. Your town hall may also hold a list of buildings with asbestos and set its own removal timetable.

Who pays to replace lead pipes in a flat?

The owner pays for the pipes inside the building, or the community of owners for shared pipes. The water company is only responsible for the public network up to the meter.

Do I have to rewire an old home if the electrical rules have changed?

No, an old installation does not have to be upgraded just because the rules changed, as long as it is still safe.