Armaflex vs Tubolit: Which Pipe Insulation Should You Choose?

June 7, 2026

Armaflex and Tubolit are two of the most widely specified pipe insulation products in the UK. Both are closed-cell elastomeric foam, both fit the same pipe sizes, and both are available from most insulation merchants. But they are not the same product — and choosing the wrong one for your application can result in non-compliance, condensation problems or unnecessary cost.

This guide compares Armaflex and Tubolit head to head across the key performance criteria so you can make the right choice for your project.

What is Armaflex?

Armaflex is manufactured by Armacell, a German company and the world's largest manufacturer of flexible foam insulation. The current standard product is Armaflex EVO, which replaced the original AF/Armaflex range. Armaflex EVO is a Class O rated closed-cell nitrile rubber (NBR) elastomeric foam with a built-in vapour barrier, Microban® antimicrobial protection and a thermal conductivity of λ ≤ 0.033 W/mK.

What is Tubolit?

Tubolit is manufactured by Armacell under a separate brand, positioned as a more cost-effective alternative to Armaflex for standard domestic and light commercial applications. Tubolit is a polyethylene (PE) foam — a fundamentally different material to the nitrile rubber foam used in Armaflex — and this difference in material has significant implications for performance.

Armaflex vs Tubolit: Key Differences

1. Fire Rating

This is the most important difference between the two products.

Armaflex EVO — Class O fire rated to BS 476 Part 6 & 7. This is the standard required for commercial buildings, HVAC installations and any application covered by Building Regulations Part B (Fire Safety). Class O is mandatory for most commercial and public building applications
Tubolit — NOT Class O rated. Tubolit is a standard polyethylene foam with no Class O fire classification. It is not suitable for commercial buildings, HVAC systems or any application where Class O is required by specification or Building Regulations

Verdict: Armaflex wins clearly. If your application requires Class O — and most commercial applications do — Tubolit is not an option. Tubolit is only suitable for domestic applications where Class O is not specified.

2. Thermal Performance

Armaflex EVO — thermal conductivity λ ≤ 0.033 W/mK at 0°C. This is among the lowest of any flexible pipe insulation product
Tubolit — thermal conductivity λ ≈ 0.038–0.040 W/mK. Noticeably higher than Armaflex, meaning more heat loss or gain for the same wall thickness

Verdict: Armaflex wins. For the same wall thickness, Armaflex provides better thermal performance than Tubolit. To achieve equivalent performance with Tubolit, you would need a thicker wall — which partially offsets the cost saving.

3. Vapour Resistance

Armaflex EVO — water vapour resistance factor μ ≥ 10,000. This extremely high vapour resistance means Armaflex acts as its own vapour barrier, preventing moisture from migrating through the insulation and condensing on cold pipe surfaces
Tubolit — water vapour resistance μ ≈ 3,000–5,000. Significantly lower than Armaflex, meaning Tubolit provides less protection against vapour diffusion and condensation on cold pipework

Verdict: Armaflex wins clearly. For chilled water, cold water and refrigeration pipework where condensation control is critical, Armaflex's superior vapour resistance is essential. Tubolit is not suitable for chilled water or refrigeration applications.

4. Temperature Range

Armaflex EVO — -50°C to +105°C continuous operating temperature
Tubolit — approximately -40°C to +85°C. Lower maximum temperature than Armaflex

Verdict: Armaflex wins. For high-temperature heating applications above 85°C, Tubolit is not suitable.

5. Antimicrobial Protection

Armaflex EVO — incorporates Microban® antimicrobial technology, inhibiting the growth of mould, mildew and bacteria on the insulation surface. Important for HVAC and chilled water applications where surface condensation could otherwise support mould growth
Tubolit — no antimicrobial protection

Verdict: Armaflex wins.

6. Price

Tubolit — typically 30–50% cheaper than Armaflex EVO for equivalent pipe size and wall thickness
Armaflex EVO — premium priced, reflecting its superior performance across all technical criteria

Verdict: Tubolit wins on price. For domestic heating and plumbing applications where Class O is not required and condensation control is not critical, Tubolit offers a genuine cost saving.

When to Use Armaflex

Any commercial building application — Class O is almost always required
Chilled water and air conditioning pipework — superior vapour resistance is essential
Refrigeration pipework — low thermal conductivity and high vapour resistance required
HVAC systems in commercial, public and industrial buildings
Any application where the specification calls for Class O elastomeric foam
High-temperature heating above 85°C
Applications requiring antimicrobial protection

When Tubolit May Be Acceptable

Domestic central heating and hot water pipework in a private dwelling
Domestic cold water supply in a heated building
Applications where Class O is not specified and condensation control is not required
Budget-constrained domestic projects where performance requirements are minimal