Asbestos Insulation: Thermal Lagging & Sprayed Coatings

Why Asbestos Insulation Is So High-Risk

Asbestos insulation is one of the most hazardous materials found in UK properties. Used extensively for its fireproofing and thermal properties, it is commonly found in buildings constructed or refurbished between the 1950s and the late 1980s. Unlike bonded materials such as asbestos cement, insulation is usually unbonded, meaning the fibres are not locked into a hard matrix. Even a slight vibration or draft can release large numbers of microscopic fibres into the air, which is why it is treated as the most dangerous category of asbestos-containing material (ACM).

Common Forms and Composition

Asbestos insulation varies significantly in appearance but is notorious for how easily it crumbles.

• High Concentration: This material often contains 80% to 100% asbestos fibre, typically a blend of Chrysotile (white), Amosite (brown) and Crocidolite (blue).
• Physical Properties: The fibres often have a loose, cotton-like or fluffy consistency. The air gaps between fibres provide excellent thermal resistance, which is exactly why it was so popular with 20th-century builders.

Where It Is Found in UK Properties

• Pipe Lagging: Most commonly found wrapped around heating pipes and calorifiers. It may be covered in a protective hard-set plaster or painted over, hiding the fibres inside.
• Boilers and Plant Rooms: Heating engineers in the 1950s, 60s and 70s used asbestos mud or pre-formed sections to insulate boilers and cylinders.
• Structural Fireproofing (Sprayed Coatings): Often called limpet asbestos, this was sprayed onto steel beams and the undersides of concrete ceilings in factories, warehouses and large residential blocks to slow structural collapse during a fire.
• Cavities and Lofts: Loose-fill asbestos was sometimes poured into loft spaces or blown into wall and floor cavities as insulation.

The Legal Position on Removal

Due to the extreme risk of fibre release, high-risk insulation materials fall under the HSE’s Asbestos Licensing Regime. Under the Control of Asbestos Regulations 2012, it is a criminal offence for an unlicensed individual to remove or significantly disturb these materials. Only contractors holding a valid asbestos licence issued by the Health and Safety Executive (HSE) are legally permitted to carry out this work, which typically requires 14 days’ formal notification to the authorities before it begins.

HSG Surveys identifies and assesses these materials as part of a survey, but we do not carry out removal work ourselves. This keeps our findings independent, and means our recommendations are based purely on risk, not on winning removal work.

Comparison of Insulation Types

Licensed Work: Highest Risk

This category covers the most dangerous materials, which are friable and can be crumbled by hand.

• Materials: Pipe lagging, sprayed coatings (limpet), loose-fill insulation, and asbestos millboard.
• Requirements: Must be carried out by an HSE-licensed contractor.
• Notice: Requires 14 days’ notification to the HSE before work starts.
• Safety: Requires strict enclosure (taped-off zones), negative pressure units, and independent four-stage air clearance testing.

Notifiable Non-Licensed Work (NNLW): Medium Risk

This is a middle ground for materials that are usually lower risk, but where the specific task, such as breaking them up, increases the chance of fibres being inhaled.

• Materials: Large-scale removal of Asbestos Insulating Board (AIB), or removing textured coatings (Artex) where the backing board is also being taken out.
• Requirements: Does not require a licensed contractor, but workers must have specific NNLW training and medical surveillance.
• Notice: The HSE must be notified before the job starts, but there is no 14-day waiting period.
• Records: Employers must keep a register of the work carried out and the names of those who did it.

Non-Licensed Work: Lowest Risk

This covers strongly bonded materials where the fibres are locked into a hard matrix such as cement or plastic.

• Materials: Asbestos cement roofing sheets, vinyl floor tiles, and textured coatings (Artex) being removed intact.
• Requirements: Can be carried out by any competent person with Asbestos Awareness and task-specific training.
• Notice: No notification to the HSE is required.
• Safety: Basic PPE (FFP3 masks and Type 5/6 coveralls) and wetting-down methods must still be used.

For further guidance, the HSE’s own asbestos pages are a helpful reference: hse.gov.uk/asbestos.