Pipe Insulation

Whether you're insulating domestic pipework, commercial HVAC, or industrial steam lines, choosing the right insulation material and thickness is critical for performance, compliance, and cost-effectiveness.

This guide covers everything you need to know about pipe insulation types, applications, Building Regulations compliance, and product selection.

Why Insulate Pipes?

Energy Efficiency & Cost Savings

Uninsulated pipes lose heat (or gain heat in cooling systems), wasting energy and increasing running costs. Proper insulation can reduce heat loss by up to 90%, significantly lowering energy bills.

Condensation Prevention

Cold pipes in warm environments cause condensation, leading to water damage, mould growth, and structural issues. Closed-cell insulation with high water vapour resistance prevents condensation formation.

Freeze Protection

Insulated pipes are less likely to freeze in cold weather, reducing the risk of burst pipes and costly water damage.

Temperature Maintenance

Insulation maintains fluid temperature in heating and cooling systems, ensuring consistent performance and reducing system cycling.

Building Regulations Compliance

Part L of the Building Regulations (England & Wales) mandates minimum insulation standards for pipework in new builds and renovations. Non-compliance can result in failed inspections and remedial work.

Noise Reduction

Insulation dampens noise from water flow, pump vibration, and thermal expansion, improving acoustic comfort in buildings.

Types of Pipe Insulation

Elastomeric Insulation (K-FLEX ST & ST/SK)

Premium closed-cell rubber insulation for HVAC, refrigeration, and chilled water systems.

• Material: Nitrile rubber (NBR/PVC)
• Temperature Range: -40°C to +105°C
• Fire Rating: BL-s2,d0
• Water Vapour Resistance: μ ≥ 7,000 (excellent condensation control)
• Best For: Commercial HVAC, refrigeration, chilled water, condensation-prone applications
• Formats: Pre-slit tube, self-seal (ST/SK), sheet

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Polyethylene (PE) Foam Insulation (K-FLEX PE & PE PLUS)

Cost-effective closed-cell foam for domestic heating, plumbing, and standard commercial applications.

• Material: Closed-cell polyethylene foam
• Temperature Range: -40°C to +105°C
• Fire Rating: DL-s1,d0 (PE) or BL-s1,d0 (PE PLUS)
• Water Vapour Resistance: μ ~1,500 (good for most domestic applications)
• Best For: Domestic heating, plumbing, budget-conscious projects, standard commercial HVAC
• Formats: Pre-slit tube, colour-coded (red/blue)

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Mineral Wool Insulation (K-FLEX K-Rock)

A1 non-combustible insulation for high-temperature and fire-rated applications.

• Material: Mineral wool with aluminium foil facing
• Temperature Range: Up to +250°C
• Fire Rating: A1 (Non-combustible)
• Best For: Industrial steam, fire-rated compartments, high-temperature process pipework
• Formats: Pre-formed pipe sections (1m lengths)

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Solar HT Insulation (K-FLEX SOLAR HT)

UV-protected EPDM insulation for outdoor and solar thermal applications.

• Material: UV-resistant EPDM rubber
• Temperature Range: -40°C to +150°C
• Fire Rating: BL-s2,d0
• Best For: Solar thermal systems, outdoor pipework, high-temperature applications

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Choosing the Right Pipe Insulation

By Application

By Pipe Temperature

Insulation Thickness Guide

Part L Building Regulations (England & Wales)

Part L specifies minimum insulation thickness based on pipe diameter and location (heated/unheated spaces). Typical requirements:

Note: These are minimum requirements. Thicker insulation provides better energy efficiency and condensation control.

Condensation Control

For chilled water and refrigeration systems, insulation thickness must prevent surface condensation. Typical guidance:

• HVAC (7-12°C): 13-19mm wall thickness
• Chilled Water (4-7°C): 19-32mm wall thickness
• Refrigeration (-20 to 0°C): 25-40mm wall thickness

Installation Tips

General Best Practices

• Ensure pipes are clean, dry, and free from rust before installation
• Use the correct adhesive for the insulation type (K-FLEX 520 for elastomeric, tape for PE)
• Seal all joints, seams, and penetrations to maintain the vapour barrier
• Support long horizontal runs every 1-2 metres to prevent sagging
• Insulate valves, fittings, and flanges with pre-formed sections or custom-cut pieces

Condensation-Prone Applications

• Use closed-cell insulation with high water vapour resistance (μ ≥ 7,000)
• Ensure continuous vapour barrier with no gaps or damage
• Seal all joints with vapour-barrier tape
• Consider additional thickness in high-humidity environments

View Detailed Installation Guides →

Frequently Asked Questions

What thickness of pipe insulation do I need?

It depends on pipe temperature, diameter, and location. For domestic heating in heated spaces, 20-25mm is typical. For chilled water, 19-32mm. For refrigeration, 25-40mm. Check Part L Building Regulations for minimum requirements.

Can I use PE foam for chilled water pipes?

PE foam can be used for mild chilled water applications (10-15°C), but elastomeric insulation (K-FLEX ST) is recommended for better condensation control due to higher water vapour resistance (μ ≥ 7,000 vs ~1,500).

Do I need to insulate hot water pipes?

Yes, Part L Building Regulations require insulation on all hot water pipes in new builds and renovations. It reduces heat loss, saves energy, and maintains water temperature.

Can pipe insulation be used outdoors?

Use K-FLEX SOLAR HT for outdoor applications - it's UV-protected and weather-resistant. Standard ST and PE products are designed for indoor use only.

How do I prevent condensation on cold pipes?

Use closed-cell insulation with high water vapour resistance (K-FLEX ST with μ ≥ 7,000), ensure adequate thickness, and seal all joints with vapour-barrier tape.

Is pipe insulation fire-rated?

Yes, all K-FLEX products are fire-tested to EN 13501-1. Fire ratings range from DL-s1,d0 (PE) to A1 non-combustible (K-Rock mineral wool).

Related Resources

• Elastomeric Pipe Insulation Guide
• Mineral Wool Pipe Insulation Guide
• K-FLEX Premium Product Range
• Technical Data Sheets & Installation Guides
• Knowledge Centre & FAQs

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