Condensation Control Pipe Insulation
Condensation Control Pipe Insulation
Condensation forms on cold pipework when warm, moist air contacts a surface below the dew point. Left untreated, it causes corrosion, mould growth, water damage and energy loss. The right pipe insulation prevents condensation by creating a thermal barrier that keeps the pipe surface above the dew point temperature.
Read our full guide: Condensation on Pipes — Causes, Prevention and the Right Insulation.
Why Closed-Cell Insulation is Essential for Condensation Control
Not all pipe insulation prevents condensation. Open-cell foam allows water vapour to pass through and reach the cold pipe surface, where it condenses. Only closed-cell insulation — such as Armaflex, K-Flex or Kaimann elastomeric rubber — provides the low water vapour permeability needed to reliably prevent condensation.
- Closed-cell structure — blocks water vapour transmission to the pipe surface
- Low lambda value — minimises heat gain on cold pipework
- Seamless installation — joints and seams must be fully sealed to prevent moisture bridging
- Correct wall thickness — thicker insulation is required in humid environments or where pipes run at very low temperatures
Open-Cell vs Closed-Cell Pipe Insulation
| Property | Open-Cell Foam (e.g. Tubolit, Climaflex) | Closed-Cell Elastomeric (e.g. Armaflex, K-Flex) |
|---|---|---|
| Vapour resistance | Low — allows moisture through | High — blocks moisture transmission |
| Condensation control | Not suitable | Excellent |
| Best for | Hot water, heating pipework | Chilled water, refrigeration, cold pipework |
| Fire rating | Class 1 | Class O |
| Flexibility | Good | Excellent |
Where Condensation Control Insulation is Required
- Chilled water pipework in HVAC systems
- Refrigeration and air conditioning pipework
- Cold water supply pipes in humid environments
- Fan coil unit connections
- Cold rooms and food storage facilities
- Boiler condensate pipes (to prevent freezing)
Armaflex, K-Flex and Kaimann for Condensation Control
All three of the major elastomeric foam brands we stock are suitable for condensation control applications:
- Armaflex EVO — The market-leading closed-cell elastomeric insulation. Class O fire rated, excellent vapour resistance, widely specified for commercial HVAC and chilled water systems.
- K-Flex ST — High-quality closed-cell elastomeric insulation, an excellent alternative to Armaflex. Available in self-seal versions for faster installation.
- Kaimann — Premium closed-cell elastomeric insulation for demanding commercial and industrial applications.
Choosing the Right Wall Thickness
The required insulation thickness for condensation control depends on the pipe temperature, ambient temperature and relative humidity. In standard UK commercial conditions, 19mm wall is typically the minimum for chilled water pipework. In high-humidity environments or at lower pipe temperatures, 25mm or 32mm wall may be required. Read our Armaflex thickness guide for detailed guidance.
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15mm | 22mm | 28mm | 35mm | 42mm | 54mm
Related Collections
- Armaflex Pipe Insulation
- Armaflex EVO Pipe Insulation
- Refrigeration Pipe Insulation
- Armaflex Sheet Insulation
Frequently Asked Questions
What causes condensation on pipes?
Condensation forms when warm, humid air contacts a pipe surface that is below the dew point temperature. This is most common on cold water pipes, chilled water systems and refrigeration pipework.
Does standard foam pipe insulation prevent condensation?
No. Standard polyethylene foam (such as Tubolit or Climaflex) is open-cell and allows water vapour to pass through. Only closed-cell insulation such as Armaflex, K-Flex or Kaimann elastomeric rubber reliably prevents condensation on cold pipework.
How thick does condensation control insulation need to be?
This depends on pipe temperature, ambient temperature and humidity. For standard UK HVAC conditions, 19mm wall is typically the minimum. In high-humidity environments or at lower pipe temperatures, 25mm or 32mm may be required. See our thickness guide for full details.
Can I use Armaflex on condensate pipes?
Yes. Armaflex is an excellent choice for boiler condensate pipes, particularly external runs that are vulnerable to freezing in winter.
Is K-Flex suitable for condensation control?
Yes. K-Flex ST and K-Flex Evo are closed-cell elastomeric insulation products with excellent vapour resistance, making them fully suitable for condensation control on chilled water, refrigeration and cold pipework. K-Flex is a high-quality alternative to Armaflex.
What is the difference between Armaflex and K-Flex for condensation control?
Both Armaflex and K-Flex are closed-cell elastomeric foam products with similar thermal and vapour resistance properties. Armaflex is the most widely specified brand in the UK, while K-Flex is often selected as a cost-effective alternative with comparable performance. Read our Armaflex vs K-Flex guide for a full comparison.
