15mm Pipe Insulation

15mm pipe insulation fits copper and plastic pipe with a 15mm outside diameter — the most common pipe size in UK domestic and commercial plumbing and heating systems. Whether you're insulating hot and cold water pipes, central heating flow and return, or condensate pipework, we stock every type of 15mm pipe insulation from the UK's leading manufacturers including Armaflex, K-Flex, Rockwool and polyethylene foam.

Types of 15mm Pipe Insulation

Armaflex EVO 15mm — Class O closed-cell nitrile rubber foam with built-in vapour barrier. The professional's choice for HVAC, chilled water and condensation-sensitive applications. Available in 9mm, 13mm, 19mm and 25mm wall, standard and self-seal
K-Flex ST 15mm — Class O elastomeric foam, equivalent performance to Armaflex at a competitive price. Available in 9mm, 13mm, 19mm and 25mm wall
Rockwool Rocklap 15mm — Mineral wool with foil facing for high-temperature applications up to 750°C. A1 non-combustible. Ideal for steam, high-temperature heating and fire-rated installations
Tubolit DG 15mm — Cost-effective polyethylene foam lagging for standard domestic heating and plumbing. Available in 9mm and 13mm wall. Not suitable where Class O fire rating or condensation control is required

Which Wall Thickness Do I Need?

9mm wall — Condensation control on chilled water and cold pipework in conditioned spaces. Minimum specification for cold water in heated buildings
13mm wall — Standard for domestic heating, hot water and cold water pipework. Meets Part L Building Regulations for most domestic applications
19mm wall — Enhanced performance for commercial HVAC, chilled water and exposed pipework. Meets Part L for commercial heating applications
25mm wall — Maximum thermal performance for chilled water, refrigeration and unheated spaces

BS 5422 for 15mm Pipe Insulation

For LTHW commercial heating on 15mm OD pipework, BS 5422 requires a minimum of 25mm Kooltherm or 19mm Armaflex EVO. For domestic hot water pipework, Part L requires a minimum of 13mm insulation. Read our full guide: BS 5422 Pipe Insulation Standards Guide.

15mm Pipe Insulation — Common Applications

Domestic hot and cold water supply pipework
Central heating flow and return pipework
Condensate pipework from boilers and heat pumps
Chilled water pipework in HVAC systems
Frost protection on exposed pipework
Underfloor heating manifold connections

How to Measure Pipe Insulation

Pipe insulation is sized by the outside diameter (OD) of the pipe, not the bore. For standard UK copper pipe, 15mm refers to 15mm OD. Always measure the outside of the pipe before ordering — do not use the nominal bore size.