What is asbestos?
Asbestos is the collective name for a group of naturally occurring silicate minerals that can be split into very thin, strong fibres. The most used types are white asbestos (chrysotile), brown asbestos (amosite) and blue asbestos (crocidolite). The fibres withstand heat, acid and wear, they conduct neither heat nor electricity, and they can be mixed into cement, glue, paint and insulation without weakening the material.
That is why asbestos was used in so many building materials from the early 1900s: it was cheap, durable and fire-retardant. In Denmark, asbestos-containing materials were common in homes built or renovated between 1900 and 1990, and those are still the homes where you find them today.
Why is asbestos dangerous?
The danger lies in the fibres. When asbestos-containing material is broken, drilled, sanded or crumbles, it releases fibres so fine that they float in the air and can be inhaled. They are too small to be coughed up again and lodge in the lung tissue, where the body cannot break them down.
Inhaling asbestos fibres can cause asbestosis (scarring of the lungs), lung cancer and mesothelioma, a cancer of the lung lining seen almost only after asbestos exposure. The diseases develop slowly and typically appear decades after the exposure. That is why the rules are about avoiding dust, not about avoiding the material itself: an intact asbestos roof or an intact ceiling panel does not release fibres on its own.
An intact material can therefore stay in place or be encapsulated. If the material is damaged, or has to be drilled, cut or taken down, it must be handled as asbestos work with the methods and protective equipment the rules require.
When was asbestos banned in Denmark?
The ban came in several steps, which is why the year of construction does not give a single answer:
- 1972: Ban on virtually all use of asbestos, including for insulation. The ban came with dispensations, especially for asbestos cement.
- 1986: The last dispensations for indoor use ended.
- 1988: Production of asbestos-containing fibre cement (eternit) sheets in Denmark stopped.
- 1990: The last dispensations for outdoor use ended. Remaining stocks of asbestos-containing roof sheets were laid until around 1990.
The practical rule of thumb is therefore: if the house was built or renovated before 1990, it can contain asbestos. If it was built after, the likelihood is small but not zero, because building materials were used up and foreign products followed other timelines.
Where does asbestos hide in the house? By year of construction
Asbestos was used in widely different materials, and they were phased out at different times. That is why the year the house was built, or the year of the last renovation, tells you which materials to expect. The periods here come from the Danish Building Research Institute's guidance on asbestos, as reproduced by the Working Environment Authority:
| Year built | Typical materials | Where in the house |
|---|---|---|
| Before 1972 | All types were typically used: fibre-cement roofs, soft ceiling panels, vinyl and floor glue, tile adhesive, filler and plaster – and pipe insulation of diatomite and asbestos board, used until the ban on asbestos for insulation in 1972. | Basement and boiler room (pipes and boilers), ceilings, bathroom and kitchen, roof |
| 1972–1980 | Insulation was banned, but tile adhesive, floor glue and vinyl , filler and sealant, plaster and ceiling panels were typically used with asbestos until around 1980. Fibre-cement roofs with asbestos were still being laid. | Bathroom and kitchen, ceilings and walls, roof |
| 1980–1986 | The last dispensations for indoor use ran until 1986. Fibre-cement slates with asbestos were produced until 1986, and corrugated sheets of asbestos cement were still being laid. | Roof and facade; a few indoor materials can still occur |
| 1986–1990 | Indoors, asbestos was phased out. Asbestos-containing corrugated sheets were produced until 1988 and laid from remaining stock until around 1990; the same goes for fibre-cement facade panels and window sills. | Roof, facade, window sills |
| After 1990 | The likelihood is small but not zero: remaining stock was used up, and foreign products followed other timelines. Only a sample gives an answer. | Rarely, typically only with reused or imported materials |
The table is not exhaustive. Asbestos was also in ventilation ducts, electrical panels, gaskets, fire protection and facade panels. If your house is from before 1990, it is safer to ask where asbestos is not than where it is.
Checklist: 13 places asbestos can sit
Go through the house from roof to basement with this list. It says where asbestos was typically used, not whether there is asbestos in your house; only a sample shows that.
- Roof sheets: corrugated sheets and fibre-cement slates of asbestos cement, laid before around 1990. The sheet number is a hint, the sample is the answer.
- Eaves and fascia: flat fibre-cement boards under the eaves and on the fascia, often painted to look like wood.
- Facade panels and window sills: flat fibre-cement panels on gables and facades, and fibre-cement sills under the windows.
- Ceiling panels: soft, light panels with holes or patterns from 1954 to 1980, and hard Internit boards from 1956 to 1979.
- Wall boards and cladding: hard fibre-cement boards behind radiators, in utility rooms, in garages and sheds.
- Tile adhesive: grey or black adhesive under tiles in bathrooms and kitchens from the 1960s and 70s, until around 1980.
- Floors: vinyl tiles, sheet vinyl and the black bitumen glue underneath them, from 1930 to 1980.
- Filler, sealant and plaster: skimmed ceilings and walls, sealant around windows and asbestos plaster, until around 1980.
- Pipe insulation: diatomite, asbestos board and gauze around heating pipes, especially in houses from before 1972 and to a lesser extent until around 1980.
- Boilers and furnaces: insulation, gaskets and rope seals in old boilers, furnaces and stoves.
- Ventilation ducts and flues: pipes and ducts of asbestos cement for ventilation and extraction.
- Electrical panels and fire protection: backing boards in old electrical panels and fire protection around chimneys and penetrations.
- Sheds, carports and outbuildings: corrugated sheets on the small buildings that are often forgotten once the house has been checked.
If you tick one or more points in a house from before 1990, the next step is not to touch it but to have a sample taken of that exact material.
What does asbestos look like?
The short answer is that you cannot see it. The asbestos fibres are mixed into cement, glue or plaster, and the material looks like the material without asbestos. A fibre cement sheet with asbestos and one without are identical to the eye. Tile adhesive with asbestos is grey, as tile adhesive is. There is no colour, smell or surface by which you can recognise asbestos, and not in a photo either.
For Danish corrugated fibre cement sheets there is one hint you can use: the number stamped into the sheet. If the sheet has an 8-digit number starting with 4 or 5, or a number with letters (such as NT), it was made without asbestos. If it has a 5–7 digit number without letters, typically starting with 0, 1, 3, 5, 6, 7, 8 or 9, it usually contains asbestos. Foreign sheets cannot be identified from the number.
The number is a hint, not an answer. It can be hidden under moss, the sheets may have been laid from leftover stock from several production runs, and it says nothing about the roof beneath the sheets. The only thing that gives an answer is a sample of the material, analysed in a laboratory. That applies to roof sheets, and it applies to everything else.
What you can see are the materials asbestos typically sat in: grey corrugated sheets with a stamped number and a rough, fibrous broken edge; white or grey pipe insulation wrapped in cloth or plaster around heating pipes; black or grey adhesive under old tiles; soft, light ceiling panels with holes or patterns. If you recognise one of them in a house from before 1990, that is not an answer. It is a reason to have a sample taken.
What do you do if you suspect asbestos?
The Working Environment Authority's rule is simple: if there is the slightest reason for suspicion, the work must be treated as asbestos work until a sample has shown otherwise. That gives three steps:
- Leave the material alone. Do not drill, sand, break or scrape it, and do not sweep or vacuum dust from it with an ordinary vacuum cleaner.
- Have a sample taken. An asbestos survey takes samples of the relevant materials and has them analysed in a laboratory. Sampling does not need to be notified to the Working Environment Authority, and you get a written result per material.
- Plan from the result. Intact asbestos can stay in place or be encapsulated; damaged asbestos, or asbestos in the way of a renovation, must be removed, and that requires an authorisation.
If you are buying a house from before 1990, have the samples taken before you sign. An asbestos survey costs a fraction of a removal, and it tells you what you are actually taking over.
