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 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

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)

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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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 Climaflex) is open-cell and allows water vapour to pass through. Only closed-cell insulation such as Armaflex 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. 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.