Risks in a House Built Before 1950: What to Check

The three things worth the most attention in a house from this era are radon from blue concrete, asbestos in older materials, and an ungrounded electrical system. The rest of this page is things you tick off calmly, not things you need to be afraid of.

And the most important point first: an old house is not the same as a house in poor condition. Many pre-war houses are solidly built and in fine shape. The point is not that the house is old, but that certain things come with the period and are therefore worth looking for. Once you know what you are looking for, it becomes a list to tick off, not a cloud of worry.

Blue concrete and radon

Blue concrete (blåbetong) is a blue-grey lightweight aerated concrete that was made between 1929 and 1975. The material contains a raised level of radium, which decays and gives off radon gas, and roughly 400,000 Swedish homes are affected. It is most common in Stockholm, the Mälardalen region, Gothenburg and Västerås.

Worth knowing: a raised radium content does not automatically mean high radon levels indoors. Ventilation plays a big part, and the only way to know is to measure. The reference level for radon in homes is 200 Bq/m3, and action should be taken if the level is exceeded.

What you check:

• Ask for a radon measurement report (radonmätningsprotokoll). A proper long-term measurement is done during the heating season.
• Look for blue-grey lightweight concrete in the walls.
• Note whether earlier measurements showed values above 200 Bq/m3.

What it usually costs: a common fix such as a radon sump or improved ventilation often lands around 15,000-50,000 kr. Removing the blue concrete entirely is a bigger job and can cost considerably more, but that is rarely needed.

Asbestos

Asbestos was banned in Sweden in 1982, so expect that it may be present in materials in houses built up to then. It was found in, among other things, eternit (asbestos cement) on roofs and facades, in floor tiles and sheet flooring, in sealants and grout, and in pipe insulation.

The reassuring part here is that asbestos is generally harmless as long as the material sits undisturbed. The risk mainly arises during renovation, when material is broken up and dust is released. So treat material from before 1982 as suspect, and plan for sampling before you tear into it or drill.

What you check:

• Eternit sheets on the facade or roof.
• Grey or black floor tiles.
• Older pipes with white insulation.

What it usually costs: asbestos removal often falls in the range of 50,000-300,000 kr, depending on where it is and how much needs to be taken out. If you do not need to renovate those parts, it is usually not urgent.

Ungrounded electrical system

Wiring from this era often lacks grounding, and the cabling is frequently undersized for how much electricity a modern household draws. That can create both a fire and a shock risk, so it is worth looking at early.

What you check:

• Screw-in fuses (the old plug fuses) in the fuse box.
• Two-pin sockets with no grounding.
• Whether there is no residual-current device (earth-leakage breaker).

What it usually costs: a rewire or upgrade of the electrics often falls in the range of 50,000-200,000 kr, more if the whole house needs rewiring. An electrical inspection (elbesiktning) gives you far firmer ground than a feeling at the viewing.

Other things to tick off

These are common age and condition questions for the period. They are rarely dramatic on their own, but good to have a handle on.

Risk	What you check	Approximate cost
Inadequate ventilation	Ask for the OVK report, check whether windows have been replaced without ventilation work	around 80,000-250,000 kr
Basement with damp problems	White salt deposits, damp patches, a mouldy smell, flaking paint	around 100,000-350,000 kr
Poor ground-floor insulation	Draughts at the skirting boards, low energy class	around 50,000-150,000 kr
Energy-hungry construction	Check the energy class, ask for past heating costs	varies with the house
Chimney stack with cracks	Ask whether the chimney stack is approved by the chimney sweep	varies
Cast-iron drains	Ask whether relining or replacement has been done, and whether there have been blockages	varies

A short orientation on a couple of these. Natural-draught ventilation (självdrag) was built for leakier houses, and often works less well after windows have been replaced and the house has been further insulated. Older basements often lack modern drainage (dränering) and a moisture barrier, so damp can rise through floors and walls. Cast-iron drains rust from the inside and have a lifespan in the order of 50-70 years, so in a pre-war house it is reasonable to ask whether they have been replaced.

What you do

• Ask the estate agent for the radon measurement report, the OVK report and any electrical inspection in advance.
• Book your own surveyor (besiktningsman), and ask them to look especially at the electrics, damp in the basement, and ventilation.
• Treat all material from before 1982 as possible asbestos until a sample says otherwise, especially if you are planning to renovate.
• Ask for past heating costs so you see the real monthly cost, not just the price.
• Add up the work you actually intend to do in the first few years, and fold it into what the house costs to own.