Foam Pipe Insulation

Foam pipe insulation is the most widely used type of pipe insulation in the UK, covering both elastomeric foam and polyethylene foam products. Lightweight, flexible and easy to install, foam pipe lagging is the first choice for domestic plumbing, central heating, chilled water, refrigeration and HVAC pipework across a wide range of applications.

At Pipelagging, we stock the UK's most comprehensive range of foam pipe insulation, including Armaflex elastomeric foam, K-Flex, and Tubolit polyethylene foam. Available in all standard pipe sizes from 15mm to 114mm bore, with a range of wall thicknesses to suit domestic and commercial applications.

Types of Foam Pipe Insulation

Elastomeric Foam Pipe Insulation

Elastomeric foam is a closed-cell nitrile rubber foam with a very low thermal conductivity and high vapour resistance. It is the professional standard for commercial and industrial pipework, and is increasingly specified for domestic applications where performance requirements are higher than standard polyethylene foam can meet.

Key properties:

• Closed-cell structure prevents moisture ingress and condensation
• High vapour resistance — essential for chilled water, refrigeration and cold pipework
• Fire performance varies by product grade — consult the relevant product datasheet for reaction-to-fire classification
• Wide temperature range: -50°C to +105°C (standard grades)
• Flexible — bends around pipework without cutting or jointing
• Available in self-seal versions for faster installation

Best applications: HVAC pipework, chilled water systems, refrigeration, domestic hot and cold water (Part L compliance), condensation-critical applications.

• Armaflex Pipe Insulation — the world's leading elastomeric foam brand
• K-Flex Pipe Insulation — high-performance elastomeric foam alternative

Polyethylene Foam Pipe Insulation

Polyethylene foam pipe insulation is a cost-effective, lightweight option for standard domestic heating and hot water applications. Tubolit is the most widely used polyethylene foam pipe insulation in the UK, available in split and self-seal versions for easy installation on new and existing pipework.

Key properties:

• Lightweight and easy to handle
• Simple to cut with scissors or a knife
• Cost-effective — the most affordable foam pipe insulation option
• Available in split and self-seal versions
• Suitable for domestic hot and cold water and central heating pipework

Best applications: Domestic hot and cold water pipes, central heating flow and return, condensate pipes, pipes in lofts, garages and unheated spaces, retrofit insulation on existing pipework.

• Tubolit Pipe Insulation — the UK's most popular polyethylene foam pipe insulation

Elastomeric Foam vs Polyethylene Foam — Which Should You Choose?

For condensation-critical applications — chilled water, refrigeration, cold water services — elastomeric foam is always the correct choice. Its closed-cell structure provides the vapour barrier needed to prevent condensation forming within or on the surface of the insulation. Polyethylene foam does not provide sufficient vapour resistance for these applications.

For standard domestic hot water and central heating pipework where condensation is not a concern, polyethylene foam (Tubolit) is a cost-effective and perfectly adequate solution.

Selecting the Right Bore Size and Wall Thickness

Foam pipe insulation is sized by the internal bore diameter, which should match the outside diameter (OD) of the pipe being insulated. For common UK copper tube: 15mm copper has a 15mm OD, 22mm copper has a 22mm OD, 28mm copper has a 28mm OD, and so on — the nominal size and OD are the same for copper tube. For steel or other pipe materials, always check the declared OD against the insulation bore size before ordering. See our Copper Pipe Sizes Guide for full sizing detail.

Wall thickness selection depends on the application:

• Domestic heating and hot water — the required insulation thickness depends on pipe size, system conditions and the thermal performance of the insulation. Follow the applicable Approved Document L guidance, BS 5422:2023 where relevant, and current manufacturer technical data.
• Chilled water and refrigeration — required wall thickness depends on pipe temperature, ambient conditions, relative humidity and the insulation's vapour resistance. Elastomeric foam wall thickness for condensation control must be determined from manufacturer condensation-control tables for your specific design conditions — a single generic thickness cannot be applied universally.
• Frost protection — required wall thickness depends on pipe size, expected minimum ambient temperature, duration of exposure and insulation performance. Use manufacturer frost-protection guidance or project-specific calculations rather than assuming one standard thickness.
• HVAC and commercial — thickness is determined by BS 5422:2023 and the relevant project specification. See our BS 5422 Standards Guide for manufacturer-specific thickness tables.

Why Choose Foam Pipe Insulation?

• Easy to install — split along the length, place around the pipe and secure with adhesive or self-adhesive closure
• Lightweight — easy to handle and cut to length with scissors or a knife
• Flexible — bends around pipework without the need for pre-formed bends or fittings in most domestic applications
• Frost protection — effective protection for pipes in lofts, garages and unheated spaces
• Part L compliance — elastomeric foam in appropriate wall thicknesses meets Building Regulations Part L requirements for hot and cold water services
• Condensation control — closed-cell elastomeric foam prevents condensation on cold pipework

Shop by Pipe Size

We stock foam pipe insulation for all standard copper and steel pipe sizes. Not sure which size you need? See our Copper Pipe Sizes Guide.

• 15mm Pipe Insulation
• 22mm Pipe Insulation
• 28mm Pipe Insulation
• 35mm Pipe Insulation
• 42mm Pipe Insulation
• 54mm Pipe Insulation
• 67mm Pipe Insulation
• 76mm Pipe Insulation

Knowledge Hub — Foam Pipe Insulation Guides

• The Ultimate Guide to Pipe Lagging — Everything you need to know about pipe insulation materials and applications
• Armaflex vs K-Flex — Comparing the two leading elastomeric foam brands
• Pipe Insulation Wall Thickness Guide — Choosing the right wall thickness for your application
• BS 5422 Pipe Insulation Standards Guide — Compliance and thickness specification
• Condensation on Pipes — Causes, prevention and the right insulation
• Copper Pipe Sizes Explained — OD, nominal bore and insulation sizing guide
• Pipe Insulation — Full range including mineral wool and phenolic
• Outdoor Pipe Insulation — UV-resistant foam for external pipework
• Refrigeration Pipe Insulation — Closed-cell foam for refrigerant and chilled pipework
• Tubolit Pipe Insulation — Polyethylene foam for domestic heating and hot water

Frequently Asked Questions

What is foam pipe insulation made from?

Foam pipe insulation is made from either elastomeric foam (closed-cell nitrile rubber, such as Armaflex and K-Flex) or polyethylene foam (such as Tubolit). Elastomeric foam offers superior thermal performance and vapour resistance; polyethylene foam is a cost-effective option for standard domestic applications.

What is the difference between Armaflex and Tubolit?

Armaflex is an elastomeric foam with a very low thermal conductivity, high vapour resistance and Class O fire rating — the professional choice for HVAC, chilled water and commercial pipework. Tubolit is a polyethylene foam designed for standard domestic heating and hot water applications where the higher performance of elastomeric foam is not required. Armaflex is more expensive but significantly outperforms Tubolit in demanding applications.

Can foam pipe insulation be used on cold water pipes?

Yes, but the type matters. For cold water pipes where condensation is a risk, closed-cell elastomeric foam (Armaflex or K-Flex) is essential — its high vapour resistance prevents moisture from reaching the pipe surface. Standard polyethylene foam does not provide sufficient vapour resistance for condensation-critical cold water applications.

What wall thickness of foam pipe insulation do I need?

Required wall thickness depends on the application, pipe size, service temperature, insulation performance and the applicable specification. For domestic heating and hot water, follow the applicable Approved Document L guidance, BS 5422:2023 where relevant, and current manufacturer technical data. For chilled water and refrigeration, condensation-control thickness also depends on ambient temperature, relative humidity and the insulation system's vapour-control performance, so use the manufacturer's data for the stated design conditions. See our BS 5422 Standards Guide and Wall Thickness Guide for further guidance.

Is foam pipe insulation self-adhesive?

Self-seal versions of both elastomeric and polyethylene foam pipe insulation are available. These have a factory-applied adhesive strip along the longitudinal slit, allowing installation without separate tape or adhesive. Standard (non-self-seal) versions require Armaflex 520 adhesive or equivalent to seal the slit and butt joints.

Can foam pipe insulation be used outdoors?

Standard foam pipe insulation is not UV-resistant and will degrade if left exposed to sunlight. For outdoor applications, use a UV-stabilised product such as Armaflex HT Solar, or protect standard insulation with a PVC or aluminium cladding system. See our outdoor pipe insulation collection for suitable products.