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 common 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 through much of the 20th century and until around 1990, and they are still in many of the homes built or renovated in that period.
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 mainly about avoiding dust. The risk arises when the material is damaged or worked on.
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 main asbestos ban came in 1972, but with exemptions, so some materials were used until around 1990:
- 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 rule of thumb is therefore that a house built or renovated before 1990 can contain asbestos. If it was built later, the likelihood is small but not zero, because old 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 many different materials, which were phased out at different times. The year the house was built, or the year of the last renovation, therefore 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, plus pipe insulation of diatomite and asbestos paper, used until the ban on asbestos for insulation in 1972. | Basement and boiler room (pipes and boilers), ceilings, bathroom and kitchen, roof |
| 1972–1980 | Asbestos in 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, have any materials you suspect tested before you renovate.
Checklist: 13 places asbestos can be found
Go through the house from roof to basement with this list. It shows where asbestos was typically used, not whether there is asbestos in your house. Only a sample can show that.
- Roof sheets: corrugated sheets and fibre-cement slates of asbestos cement, laid before around 1990. The sheet number gives a clue, but only a sample gives 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 paper 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, leave the material alone and have a sample taken of that exact material.
What does asbestos look like?
You cannot see asbestos with the naked eye. 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 the same colour as adhesive without. 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 clue you can use: the number stamped into the sheet. If the sheet has an 8-digit number starting with 4 or 5, a number with letters (such as NT), or a number that starts with a small house-gable symbol, that suggests a sheet without asbestos. If it has a 5–7 digit number without letters, typically starting with 0, 1, 3, 5, 6, 7, 8 or 9, that suggests a sheet with asbestos. Foreign sheets cannot be identified from the number.
The number is a clue, 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. Only a sample of the material, analysed in a laboratory, gives an answer. That applies to roof sheets, and it applies to everything else.
What you can see are the materials asbestos was typically used 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 that the work must be treated as asbestos work if there is the slightest reason for suspicion, until a sample has shown otherwise. For you, that means 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. With an asbestos survey we arrange a sample and an analysis of each material you are unsure about, and you get the result in writing.
- Plan around the result. Intact asbestos can stay in place or be encapsulated. Damaged asbestos must be encapsulated or removed, and asbestos in the way of a renovation must be removed. Demolition requires an authorisation, except for small, short jobs.
If you are buying a house from before 1990, have the samples taken before you sign. Then you know what you are buying, and you can factor any removal into the price negotiation.