For the health controversy on Zonolite, click here. Vermiculite produced after 1990 has no asbestos in it. Because of the bad reputation it got with Zonolite it is not generally sold as insulation, although it is an excellent insulation with good fire resistance and easy pourability. You can find it in Garden centres, they use it in potting soil to help hold the humidity.
Colour: Light brown
Thermal Resistance: RSI - .016/mm R - 2.3/in. Low.
Cost: Medium
Capacity to dry out if wet: Poor
Fire Resistance: Excellent
Fungus/Vermin Resistance: Good
Limitations:
-- Absorbs moisture and dries slowly. (Great for mixing with soil for plants.)
-- Settles.
-- Not a good air barrier.
Advantages:
-- Fills irregular spaces well.
-- Easy to work with.
-- Specially coated (water resistant) type now available.
Notes:
-- Ensure that it does not plug eave vents at the time of installation and that it does not blow over the vents later with normal attic air currents.
Applications:
-- Attics and accessible enclosed cavities above ground level, such as walls, roofs and floors.
-- Can be used right up against chimneys in the space normally left open for fire protection.