How to Tell Rock Wool From Vermiculite

spiralling insulation image by jbattx from

While many types of insulation are considered harmless, other types may affect your health. Vermiculite insulation was once commonly installed in homes and is now considered dangerous, since it is often contaminated by cancer-causing asbestos. Another commonly used insulation, rock wool, is thought to be safe.

To identify which type of insulation exists in your home, it is important to learn the differences between rock wool and vermiculite.

Observe the texture of the insulation. Vermiculite insulation is loosely packed and granular in appearance, often resembling small pebbles. The size of the pieces may vary from 1/8 inch in diameter to 1/2 inch. Rock wool is made up of soft fibres, rather than loose particles, and has a cottony appearance.

Observe the colour of the insulation. Vermiculite insulation is made up of grey or brown particles that may be sprinkled with bits of reflective gold or silver mica. Rock wool can be either white, off-white or brownish white.

Slip your protective gloves onto your hands. With your gloved hands, feel the texture of the insulation. Vermiculite insulation feels granular between your fingers, almost like small pieces of gravel. In contrast, rock wool feels like dense wool.