Asbestos in glass wool is a question that comes up surprisingly often when demolishing older properties. Pure glass wool does not contain asbestos, but in the insulation works of the 1960s-1980s, different fiber materials were used side by side and they could mix with each other. In addition, in old buildings, the insulation has been changed several times, in which case the asbestos-containing insulation has remained next to or under the new glass wool. Insulation installed before 1994 may not be processed without an asbestos survey.
Was there asbestos in the glass wool as it is?
Asbestos is not normally used as a raw material in industrially produced glass wool. Glass wool is made from molten glass by drawing thin fibers, and the manufacturing process did not require the addition of asbestos. However, in some specialty insulations, especially high-temperature applications, manufacturers could mix in asbestos fibers to improve fire resistance. Such products were rare, but were found in industrial and shipbuilding sites.
Mixed insulations are the most common risk item
In practice asbestos in glass wool usually means mixed insulation where mineral wool or glass wool is installed next to or on top of asbestos-containing insulation. Typical items include:
- Pipe insulation in basements, technical rooms and flues
- Wall insulation In detached houses and apartment buildings of the 1960–1980s
- Intermediate floor insulation, where there may be asbestos in the sawdust or chippings
- Insulation of boiler rooms and chimneys
- Thermal insulation around ventilation ducts
If the insulation has been added or renewed several times, the structure may have layers of different ages and compositions on top of each other.
How can you distinguish the mixed insulation in appearance
Pure glass wool is yellowish or white and the fibers are relatively long and flexible. Mineral wool is often brown or gray. Asbestos-containing insulation can be white, gray, bluish, or brownish, and it can be powdery, fibrous, or cardboard-like. Asbestos paper or asbestos cloth around the pipe is a clear warning sign. However, a visual assessment is not enough, because the fibers are invisible to the eye and the appearance of the insulation can be misleading. Certainty can only be obtained through laboratory analysis.
The demolition risk is significant
When the old insulation is dismantled, the fibers are released into the air very easily. Irritating fibers are released from glass wool, but microscopic fibers are released from asbestos-containing insulation, which remain in the air for a long time and travel to the smallest structures of the lungs. When inhaled, the fibers cause asbestosis, lung cancer and mesothelioma. The risk does not appear immediately, but diseases typically appear with a delay of 20–40 years.
A survey is necessary before handling the insulation
Finnish asbestos legislation requires that all insulation built before 1994 be surveyed before demolition or repair work. In the survey, samples are taken from all insulation layers and their composition is analyzed. Only based on the results will it be known which insulations can be dismantled normally and which ones require an asbestos demolition permit. In this way, both health risks and contaminations that are revealed afterwards are avoided.
If your property has old insulation and you are planning a pipe or wall renovation, order an asbestos survey before starting work. A reliable analysis is the only way to confirm whether the insulation contains asbestos.