Sprayed Asbestos Coating (Limpet)

Sprayed asbestos coating, commonly known as limpet spray or sprayed limpet asbestos (SLA), is among the most dangerous asbestos-containing materials ever produced. The product was applied by spraying a wet mixture of asbestos fibres, typically crocidolite (blue asbestos) or amosite (brown asbestos), mixed with a cement or calcium sulphate binder directly onto structural steelwork, ceilings, walls, and the undersides of roofs.

The primary purpose was fire protection and thermal insulation. Sprayed coatings were ubiquitous in boiler rooms, plant rooms, service ducts, and on the structural steel frames of high-rise office blocks, factories, and public buildings. During the post-war construction boom of the 1950s and 1960s, limpet spray was the industry-standard method for achieving required fire-resistance ratings on steel columns and beams.

Sprayed asbestos coatings typically contain between 55 % and 85 % asbestos by weight, making them extraordinarily hazardous when disturbed. The material has a rough, fibrous, cement-like texture and is extremely friable; even air currents, vibration, or water leaks can cause fibre release. Because crocidolite was frequently used, the carcinogenic potency is at its highest. Exposure is strongly associated with mesothelioma, lung cancer, and asbestosis.

In the UK, the use of crocidolite and amosite in spray coatings was prohibited in 1985, and all forms of asbestos were banned in 1999. The US EPA banned spray-applied asbestos-containing material for fireproofing and insulation in 1978. Despite decades of removal campaigns, sprayed asbestos coatings are still found in many pre-1980 buildings worldwide. Identification and management or removal by licensed professionals is essential. Full enclosure removal with air monitoring is the standard approach.