Man-made mineral fibres — glass wool, stone wool, slag wool — are the most widely used insulation material in Austria. Not a problem in themselves. But if you are renovating a building from the 1970s or 80s and find yellowish, brittle insulation batts in the intermediate ceiling, it is worth taking a closer look.
Old vs. New: The Crucial Difference
MMF manufactured before the mid-1990s contain fibres that the body breaks down poorly. They are biopersistent — they remain in the lungs. IARC (the International Agency for Research on Cancer) classifies these older fibres as "possibly carcinogenic" (Group 2B).
Since around 1996, strict EU requirements for bio-solubility have applied. Modern mineral wool dissolves relatively quickly in the body and is considered harmless. Recognisable by the RAL quality mark or the label "bio-soluble" on the packaging.
The question with every renovation is therefore: old or new?
Where We Find Old MMF
In the buildings we inspect — primarily built between 1965 and 1995 — we typically find old MMF at these locations:
- Between-rafter insulation in the roof truss
- Cavity insulation in lightweight walls
- Pipe insulation in the basement
- Impact sound insulation under screeds
- Suspended ceilings in office and commercial buildings
The materials are often yellowed, brittle, and dust when touched. That dusting is precisely the problem: it releases fibres that enter the indoor air.
When You Need to Act
Old MMF in closed cavities (wall, roof, under screed): No immediate action required, as long as the insulation is not disturbed and there is no open connection to the living area.
Old MMF in open contact with indoor air (e.g. open ceilings, visible insulation): Indoor air measurement recommended. In Austria, a limit value of 50,000 fibres/m³ applies.
Renovation planned, old MMF must come out: Protective measures are mandatory — respiratory protection (minimum FFP2), protective clothing, containment of the area, HEPA extraction. Old MMF is hazardous waste and may not be disposed of in household rubbish.
What We Do
When an inspection reveals insulation that looks old and carries no quality mark, we take a material sample. The laboratory uses scanning electron microscopy (SEM) to determine whether biopersistent fibres are present.
The analysis costs from €69 (mineral matrix e.g. concrete, screed: €149). Result in 5–7 business days. This tells you whether you need special precautions during your renovation — or whether the insulation is harmless.
The Pragmatic View
MMF is not asbestos — the comparison is often made, but the differences are important. Asbestos is significantly more dangerous and requires stricter remediation measures (→ Recognizing Asbestos). With MMF, the risk is lower, the measures are simpler, the costs are manageable. But you should not ignore it — especially if you are planning a roof conversion or core renovation.
A sample before ripping it out gives you clarity and protects the tradespeople doing the work.
15-minute initial consultation, free of charge.