Vermiculite
Vermiculite is the geological name given to a group of hydrated laminar minerals that are aluminium iron magnesium silicates, a hydrous phyllosilicate mineral. Although vermiculite is often listed as a Deleterious material because of its connection to asbestos, pure vermiculite does not contain asbestos and is non-toxic. Impure vermiculite may contain, apart from asbestos, minor diopside or remnants of precursor minerals biotite or phlogopite, most mines are tested for the presence of asbestos.
Most vermiculite used in industry is exfoliated vermiculite, that is heated to a high temperature a separation of the layers of the material at micro level. This heating exfoliation process causes the vermiculite to expands to up to 12 times its original volume, converting the dense flakes of ore into lightweight porous granules which contain innumerable air layers. These air pockets make the material lightweight, with good water absorption, heat retention and fireproofing qualities.
Until the 1990's various products were made with vermiculite and asbestos, such as for example home insulation, where some amount of asbestos was added to assist with structure and fireproofing. Today, due to significant health risks vermiculite asbestos products are rare, however products containing just vermiculite continued to be used in construction as well as gardening, filtration and construction.
Vermiculite is used in the car industry for brake pads, in water treatment, seed germination and soil treatment, and in fireproof coatings. In construction it continues to be used in lightweight concrete roof structures and screed floors, as an aggregate in renders and insulating plasters, as fireproof wall boards and as loose fill cavity insulation.
The global reserves of perlite are estimated to be around 2.36 million tonnes, with around 500,00 tonnes produced each year primarily from South Africa, the US, Brazil, and Russia. Perlite is a very similar material to vermiculite with similar uses but some slightly different characteristics.
[edit] Related articles on Designing Buildings
Featured articles and news
The 2026 Compliance Landscape: Fire doors
Why 'Business as Usual' is a Liability.
Cutting construction carbon footprint by caring for soil
Is construction neglecting one of the planet’s most powerful carbon stores and one of our greatest natural climate allies.
ARCHITECTURE: How's it progressing?
Archiblogger posing questions of a historical and contextual nature.
The roofscape of Hampstead Garden Suburb
Residents, architects and roofers need to understand detailing.
Homes, landlords. tenants and the new housing standards
What will it all mean?
The Architectural Technology podcast: Where it's AT
Catch-up on the latest episodes.
Edmundson Apprentice of the Year award 2026
Entries now open for this Electrical Contractors' Association award.
Traditional blue-grey slate from one of the oldest and largest UK slate quarries down in Cornwall.
There are plenty of sources with the potential to be redeveloped.
Change of use legislation breaths new life into buildings
A run down on Class MA of the General Permitted Development Order.
Solar generation in the historic environment
Success requires understanding each site in detail.
Level 6 Design, Construction and Management BSc
CIOB launches first-ever degree programme to develop the next generation of construction leaders.
Open for business as of April, with its 2026 prospectus and new pipeline of housing schemes.
The operational value of workforce health
Keeping projects moving. Incorporating unplanned absence and the importance of health, in operations.
A carbon case for indigenous slate
UK slate can offer clear embodied carbon advantages.
Costs and insolvencies mount for SMEs, despite growth
Construction sector under insolvency and wage bill pressure in part linked to National Insurance, says report.