What Are Thermal Breaks in Aluminium Frames and Why Do They Matter?

Aluminium is one of the strongest and most popular materials used for modern windows and doors. However, on its own, aluminium is highly conductive — meaning it can transfer heat and cold very easily.

This is where thermal breaks come in. Understanding thermal breaks in aluminium frames is essential if you want energy-efficient, comfortable, and regulation-compliant windows and doors.

What Is a Thermal Break?

A thermal break is a non-conductive barrier built into an aluminium frame.
It separates the inner (warm) aluminium profile from the outer (cold) profile, reducing heat transfer between inside and outside.

Without a thermal break, cold temperatures can pass straight through the frame — leading to heat loss, condensation, and poor energy performance.

Why Aluminium Needs Thermal Breaks

Aluminium is incredibly strong and durable, but it conducts heat far more than materials like uPVC or timber.

Without a thermal break:

• Heat escapes easily in winter

• External cold transfers inside

• Internal warmth meets cold surfaces, causing condensation

Thermally broken aluminium frames solve these issues while retaining aluminium’s strength and slim sightlines.

How Thermal Breaks Work

Most modern aluminium systems use a polyamide thermal break.

This involves:

• Two separate aluminium profiles

• A rigid polyamide strip mechanically bonded between them

The polyamide material has very low thermal conductivity, dramatically reducing heat transfer while maintaining structural integrity.

Types of Thermal Breaks in Aluminium Frames

Not all thermal breaks are the same.

Key differences include:

• Width of the thermal break – wider breaks improve insulation

• Quality of the polyamide material

• How the break is bonded to the aluminium profiles

Higher-quality systems use wider, reinforced thermal breaks to achieve better U-values and improved overall performance.

How Thermal Breaks Affect Energy Efficiency

Thermal breaks play a major role in a door or window’s U-value.

Better thermal breaks mean:

• Lower heat loss

• Improved insulation

• Reduced heating costs

In many cases, the thermal break is the difference between a frame meeting or failing UK Building Regulations Part L.

Thermal Breaks and Condensation Reduction

Condensation occurs when warm, moist air meets a cold surface.

Thermal breaks:

• Keep internal frame surfaces warmer

• Reduce cold bridging

• Lower the risk of condensation forming on frames

This improves comfort and helps protect surrounding finishes.

Thermal Breaks vs Non-Thermally Broken Aluminium

Older or cheaper aluminium frames may lack proper thermal breaks.

These systems often:

• Feel cold to the touch

• Cause draughts and condensation

• Fail to meet modern energy standards

Modern thermally broken aluminium frames are now standard for residential use in the UK.

Do All Aluminium Doors and Windows Have Thermal Breaks?

Most reputable aluminium systems do — but not all.

When choosing aluminium frames, always check:

• That the system is thermally broken

• The stated frame and whole-unit U-values

• Compliance with UK regulations

This is especially important for bifold doors, sliding doors, and entrance doors, where frame size and glass area are significant.

Final Thoughts

Thermal breaks are a crucial part of modern aluminium window and door design. They allow aluminium frames to deliver slim sightlines, strength and durability without sacrificing energy efficiency.

Choosing a properly thermally broken aluminium system means:

• Better insulation

• Reduced condensation

• Improved comfort

• Compliance with UK building regulations

At Home Build Doors, we only supply aluminium systems that incorporate high-performance thermal breaks — ensuring long-term performance and peace of mind.