This article will help you understand where asbestos can be found.
This is important to know because if disturbed asbestos can be inhaled, which in time, can lead to diseases.
No new buildings contain asbestos. But older buildings (pre-1999 may contain some asbestos) and this article will help you know where asbestos might be. Our 'Where asbestos can be found' list goes from most friable asbestos to least friable asbestos. Generally speaking the greater the friability of the ACM the greater the danger. But percentage of asbestos and type of asbestos also contribute to the risk.
ACMs in Order of Friability
The friability of different Asbestos Containing Materials can be ranked as follows from most hazardous to least hazardous.
- Loose asbestos
- Sprayed coatings
- Pipe and boiler lagging
- Millboard and paper products
- Asbestos Insulating Board (AIB)
- Brake pads
- Asbestos Cement (AC)
- Textured coatings
- Floor tiles
Loose asbestos insulation
Normally found in some fire doors in between the wooden or metal facings to improve their fire rating. Also found packed around electrical cables.
Even mattresses containing asbestos were manufactured for thermal insulation, and indeed some loft insulations. Also found between floors as an acoustic insulator. The type of asbestos used is typically crocidolite or chrysotile
Sprayed Asbestos Coatings
Next we have Sprayed asbestos coatings.
Sprayed coatings usually contain 55 and 85% asbestos with a Portland cement binder. Crocidolite was the major type until 1962. It was used as an asbestos spray up to 1974.
Sprays have a high potential for fibre release if unsealed, particularly if knocked or the surface is abraded or delaminates from the underlying surface. Dust released may then accumulate on false ceilings, wiring and ventilation systems.
Typically used as Thermal and anti-condensation insulation on the underside of roofs and sometimes sides of industrial buildings and warehouses. Also used as acoustic insulation in theatres, halls etc.
Be aware that overspray of target areas was common. Generally found in dry or wet applied and trowel applied finish.
Often found in hand-applied thermal, pipe and boiler lagging, preformed pipe sections, slabs and blocks, thermal insulation containing asbestos can also be found in tape, rope, corrugated paper, quilts, felts, and blankets.
All types of asbestos have been used in Thermal Insulation. Crocidolite was used in lagging until 1970. Asbestos content varies between 6 and 85%. Various ad hoc mixtures were hand-applied on joints and bends and pipe runs. Preformed sections were widely used, such as ‘85% magnesia’ contained 15%. The ease of fibre release often depends on the type of lagging used and the surface treatment
‘Millboard’ was used for general heat insulation and fire protection as well as for insulation of electrical equipment and plant.
Crocidolite was used in some millboard manufacture between 1896 and 1965; usually chrysotile. Millboards may contain 37–97% asbestos, with a matrix of clay and starch.
Asbestos ‘Millboard’ has a high asbestos content and low density so is quite easy to break and the surface is subject to abrasion and wear
Insulating board was used for fire protection, thermal and acoustic insulation, resistance to moisture, movement and general building board.
Insulating board is found in service ducts, firebreaks, infill panels, partitions and ceilings (including ceiling tiles), roof underlay, wall linings, soffits, external canopies and porch linings.
Crocidolite was used for some boards up to 1965, and amosite up to 1980 when manufacturing ceased. Asbestos Insulating Board or AIB can be readily broken, giving significant fibre release. Significant surface release is also possible by abrasion, but the surface is usually painted or plastered. Sawing and drilling will also give significant releases.
Insulating board in cores and linings of composite products can be found in fire doors, cladding infill panels, domestic boiler casings, partition and ceiling panels, oven linings and suspended floor systems. Insulating board is used as thermal insulation and sometimes as acoustic attenuators. It can be broken by impact; significant surface release is possible by abrasion
Asbestos Papers, Felts and Cardboard
Asbestos papers were used primarily for electrical or heat insulation of electrical equipment.
They were also used in some air-conditioning systems as insulation and acoustic lining. Asbestos paper has also been used to reinforce bitumen and other products and as a facing/lining to flooring products, combustible boards and flame-resistant laminate. Corrugated cardboard has been used for duct and pipe insulation.
Asbestos paper can contain 100% chrysotile asbestos but may be incorporated as a lining, facing or reinforcement for other products, e.g. roofing felt and damp-proof courses, steel composite wall cladding and vinyl flooring. Asbestos paper is also sometimes found under MMMF insulation on steam pipes.
Paper materials, if not encapsulated or combined within vinyl, bitumen, or bonded in some way, can easily be damaged and release fibres when subject to abrasion or wear
Asbestos textiles can be found in ropes and yarns. It has been used as lagging on pipes, jointing and packing materials and as heat or fire-resistant boiler, oven and flue sealing. Asbestos textiles are found in caulking in brickwork and plaited asbestos tubing in electric cable.
Although other types of asbestos have occasionally been used in the past, crocidolite and chrysotile were widely used due to the length and flexibility of fibres.
Chrysotile was used alone since at least 1970 and the asbestos content can approach 100% unless it was combined with other fibres. Weaving reduces fibre release from products, but abrading or cutting the materials will release fibres which are likely to degrade if exposed, becoming more friable with age.
If used with caulking, fibres will be encapsulated and less likely to be released. It has been used as thermal insulation and lagging such as in fire-resisting blankets, mattresses, protective curtains, gloves aprons and overalls.
Asbestos in cloths have been manufactured since the mid-1960s with the vast majority being chrysotile and the asbestos content approaching 100%. Fibres may be released if material is abraded
Asbestos Cement Sheets
Asbestos cement sheets and tiles used for roofing and cladding comes in the following forms:
- Profiled sheets.
- Semi-compressed flat sheets and partition board.
- Fully compressed flat sheets used for tiles, slates, board and
- Pre-formed moulded products and extruded products.
Profiled sheets are used in roofing, wall cladding, permanent shuttering, and cooling tower elements and usually contain around 10–15% asbestos. Crocidolite, used between 1950–1969, and amosite used between 1945–1980, have been used in the manufacture of asbestos cement, although chrysotile, which was used until November 1999, is by far the most common type found.
It is likely to release increasing levels of fibres if abraded, hand sawn or worked on with power tools. Exposed surfaces and acid conditions will remove cement matrix and concentrate unbound fibres on surface and sheet laps. Cleaning asbestos-containing roofs may also release fibres. Semi-compressed flat sheet and partition board contained types of asbestos similar to profile boards but are known to contain between 10 to 25% asbestos.
They are mainly used as partitioning in farm buildings and infill panels for housing, shuttering in industrial buildings, decorative panels for facings, bath panels, soffits, linings to walls and ceilings, portable buildings, propagation beds in horticulture, domestic structural uses, fire surrounds, composite panels for fire protection and weather boarding.
Fully compressed flat sheet used for tiles, slates and boards can contain up to 50% chrysotile and can be found in the same locations as semi compressed flat sheet materials although generally used where stronger materials are required such as slates, board cladding and decking
Encapsulated materials include moulded asbestos cement products such as textured coatings like paints and plasters used for decorative effects on walls and ceilings. It contained between 3 and 5% chrysotile asbestos up to 1984, however old stock may have been used for several more years, as non-asbestos versions were available from the mid-1970s. Generally fibres are well contained in the matrix but may be released when old coating is sanded down or scraped off
Bitumen products include roofing felts and shingles, semi-rigid asbestos bitumen roofing, gutter linings and flashings, bitumen damp-proof courses or DPC.
It is also found in asbestos bitumen coatings on metals, such as car body underseals, and bitumen mastics and adhesives which are used for floor tiles and wall coverings. This is often in the form of chrysotile fibre or asbestos paper which is approximately 100% asbestos in bitumen matrix, at 8% chrysotile.
Though bitument products were used up to 1992, and fibre release is unlikely during normal use; roofing felts, DPC and bitumen-based sealants must not be burnt after removal
Asbestos can be found in thermoplastic floor tiles, PVC vinyl floor tiles, unbacked PVC flooring and magnesium oxychloride flooring which is used in toilets, staircases and industrial flooring.
It usually has up to 25% asbestos and contains 7% chrysotile. Paper backing is approximately 100% chrysotile asbestos and was used up to 1992.
With paper backing fibre release is unlikely to be a hazard under normal service conditions although the fibre may be released when material is cut. There may also be substantial release where flooring residue, particularly paper backing, is power sanded
Plastic/Resin Composites Asbestos-Reinforced Plastic is often found in toilet cisterns, seats, banisters, window seals, lab bench tops. Plastics usually contain between 1 and 10% chrysotile asbestos. Some amphiboles were used to give improved acid resistance, e.g. car batteries. Resins were reinforced with woven chrysotile cloth and usually contain between 20 and 50% asbestos. Fibres unlikely to be released although limited emissions can be released during cutting
If any of your staff work where asbestos could be present they need CAT A Asbestos Awareness Training.