BS 5422 Resource Centre
The complete UK reference for pipe insulation thickness, compliance and specification under BS 5422:2023
Used by heating engineers, M&E contractors, HVAC consultants and facilities managers throughout the UK
BS 5422:2023 is the British Standard specifying minimum thermal insulation thicknesses for pipework, ductwork and equipment in building services installations. It is referenced by Part L of the Building Regulations and is the primary specification standard for pipe insulation thickness in the UK.
The standard covers heating systems, chilled water systems, cold water systems and steam applications, providing thickness tables based on pipe outside diameter, operating temperature and insulation material thermal conductivity (lambda value).
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BS 5422 Explained — The Complete Guide
The definitive reference for minimum insulation thicknesses
Read more →What Thickness Pipe Insulation Do I Need?
Step-by-step thickness selection for every application
Read more →Part L Compliance for Pipe Insulation
How BS 5422 satisfies Part L of the Building Regulations
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Frequently Asked Questions
BS 5422:2023 is the British Standard specifying minimum thermal insulation thicknesses for pipework, ductwork and equipment in building services installations.
BS 5422:2023 is the specification standard used to determine minimum insulation thicknesses. It is referenced by Part L of the Building Regulations, but the obligation to comply arises from Part L itself and project requirements — not from BS 5422 directly.
BS 5422 covers pipe outside diameters from 10mm to over 100mm across heating, chilled water, cold water and steam applications.
BS 5422:2023 is commonly used to specify insulation thicknesses for domestic heating and hot water pipework. Where work is notifiable under Part L, the insulation must meet the minimum thicknesses that BS 5422 is used to determine.
BS 5422 is published by BSI and available from the BSI Shop.
The required thickness depends on the application, pipe outside diameter, operating temperature, insulation thermal conductivity, surface conditions and the performance criterion being applied. Use the relevant BS 5422:2023 tables together with current manufacturer technical data, or contact our technical team for product-selection guidance.
A calculated or tabulated minimum thickness does not always match a commercially manufactured insulation size. Where the required minimum falls between available sizes — for example, around 38mm — select a suitable available thickness that meets or exceeds the required performance, subject to BS 5422:2023, the product manufacturer's technical data and the project specification.
Need help with BS 5422 compliance?
Our technical team can advise on the correct insulation material, wall thickness and accessories for your project — from a single domestic pipe to a full commercial specification.
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