Is there asbestos in mineral wool or insulation?

Ordinary glass wool and stone wool are not asbestos products, so the wool insulation in walls and lofts is rarely where asbestos turns up. Asbestos was, however, used in other kinds of insulation: pipe and boiler lagging, sprayed insulation and fire protection, and some old insulation boards and cords. Old insulation can also be a mix of different materials, and asbestos cannot be told apart from wool by eye. That is why suspect insulation in a building built or renovated before 1994 is tested by sending a sample to a laboratory.

This article covers which types of insulation used asbestos, when insulation is worth testing, how to take a sample with as little dust as possible, and what the result means.

Does glass wool or stone wool contain asbestos?

Glass wool and stone wool are manufactured fibres, made by melting glass or rock and spinning the melt into fibres. Asbestos, by contrast, is a naturally occurring fibrous mineral. They are different materials, and mineral wool is not an asbestos product.

Wool can still irritate the skin, eyes and airways, and it is worth wearing protection when handling it. That does not mean the wool contains asbestos. Suspicion usually arises because there is another insulating material next to or on top of the wool, such as insulating compound on a pipe bend, a hard coating or an old insulation board.

Which types of insulation used asbestos?

Asbestos was used in insulation mainly where resistance to heat and fire was needed. Typical places are listed below.

Pipe and boiler lagging

Asbestos has been used in the insulation of heating and hot water pipes, steam pipes and heating boilers. On straight pipe runs the insulation may be mineral wool, while bends, branches and joints often have hand-applied insulating compound, which is a different material. More on this on the page asbestos in pipe insulation.

Sprayed insulation and fire protection

Sprayed insulation that may contain asbestos has been used to fire-protect steel structures, intermediate floors and technical spaces. It is often soft or crumbly, so it sheds dust easily if touched.

Insulation and fire protection boards

Boiler rooms, ventilation plant rooms, the surroundings of fireplaces and the inside of fire doors may contain old insulation or fire protection boards. From the outside they can look like ordinary board or be painted over.

Insulating tapes, ropes and gaskets

Old boilers, stoves, fireplace doors and fire doors have used insulating tapes, rope seals and gaskets that may have contained asbestos.

Can you identify insulation by how it looks?

Not reliably. Colour, feel or fibre length do not tell you whether a material contains asbestos. The following are still good reasons to test insulation:

• the building or heating system dates from before 1994 and the insulation has not been replaced since
• the insulation is on pipes or a boiler, or in a boiler room, heat distribution room or fire door
• the insulation is hard, chalky or paste-like, or the wool has a hard coating
• the insulation has been repaired at different times, so the same pipe run may contain different materials
• there is compound, rubble or board fragments from earlier work mixed into the wool

A wool batt or roll in a wall or loft structure, with no other insulating materials around it, is usually ordinary glass or stone wool. If you are unsure, a sample will settle it. Identifying materials more generally is covered in the article identifying asbestos.

When should insulation be tested?

Intact, covered insulation does not release fibres into the air. The risk arises when insulation is cut, torn or crushed. Insulation should be tested before pipe replacement, a boiler change, renovation of a boiler room or technical space, or removal of fire doors. It is worth checking the other materials that will be removed at the same time, for example the floor covering and its adhesive.

If the insulation is already damaged and crumbling, do not touch it. Restrict access to the space and find out what it is before any work is done there.

Where should the insulation sample be taken?

• Take the sample from the insulation that the work concerns.
• If the insulation on a straight pipe run looks different from that on a bend or joint, take separate samples.
• Take a separate sample of each different type of insulation. If the whole pipe run has the same insulation, one sample is often enough.
• Choose a spot where the covering is already open or the edge of the insulation is visible, so you do not have to break into intact insulation.

How to take a sample of insulation

Only a small piece of insulation is needed. The main thing is to disturb the material as little as possible: do not pull apart or fluff up loose insulation, but remove a small piece in one go.

1. Wear disposable gloves and a respirator of at least class FFP3. Close the door to the space and keep other people and pets away.
2. Lightly mist the sampling spot with a spray bottle. Damp insulation releases less dust.
3. Hold an open zip-lock bag under the sampling spot so that any loose material falls straight into it.
4. With a sharp knife, cut out a piece of about 2–3 centimetres that includes the covering and the full thickness of the insulation. For hard compound, use a chisel to break off a piece.
5. Seal the bag and put it inside a second bag.
6. Mark the bag with the location and material, for example "boiler room, heating pipe bend, white compound".
7. Cover the sampling spot with tape so the insulation cannot crumble, and wipe the area with a damp cloth. Do not use an ordinary vacuum cleaner.

If the insulation crumbles at the slightest touch or it is a large sprayed surface, do not take the sample yourself. More detailed instructions are in the articles how to take an asbestos sample and protecting yourself when sampling asbestos.

What does the result of an insulation sample mean?

Onelab analyses the sample with a JEOL SEM-EDS electron microscope in accordance with ISO 22262-1, and the result is sent by email, typically on the day the sample arrives. The result tells you whether asbestos was detected in the sample you sent.

• No asbestos detected: the result applies to the sampling spot and similar insulation. Different parts of the same pipe run, such as the compound on bends and repaired sections, are tested separately.
• Asbestos detected: leave the insulation in place and do not open, cut or remove it yourself. Keep the covering intact and cover any damaged spots. The insulation is removed by a company authorised for asbestos removal work, and this is best built into the renovation schedule from the start.

If the insulation is part of a larger renovation or demolition that requires an on-site asbestos survey, the survey is carried out on site by a qualified surveyor. Onelab is a laboratory, and on-site surveys are handled by our sister brand AsbestiPro.

How much does the analysis of an insulation sample cost?

The analysis costs €39.90 + VAT per sample, and the price is the same for 1–100 samples. Orders of more than 100 samples can be priced separately. Postage is not included. You can order the analysis online and send the sample to the laboratory by post.