Thermally Broken Windows & Doors

Thermally Broken Windows & Doors — What They Are and Why They Matter

Your home should feel like your sanctuary – designed for comfort, style, and lasting performance. At Stock Windows & Doors, our thermally broken aluminium range gives you the best of both worlds: modern, innovative design paired with outstanding energy efficiency. Create a home that looks as good as it feels, with windows and doors built to enhance both style and comfort.

What is a thermal break?

A thermal break is an insulating barrier placed between the inside and outside faces of an aluminium window or door frame. Because aluminium is a very good conductor of heat, a continuous metal frame will readily transfer heat (or cold) from one side to the other. A thermal break — typically a polyamide or similar insulating strip — interrupts that heat path and dramatically reduces heat transfer through the frame.

How a thermal break works

• Aluminium exterior ↔ Aluminium interior: without a thermal break, the metal forms a direct pathway for heat.
• With a thermal break: an insulating strip separates the two metal pieces so heat must pass through a much less conductive material first — slowing the transfer and reducing energy loss.
• When combined with double or triple glazing, thermal breaks help create a complete thermal barrier across the entire window or door assembly.

Benefits of thermally broken frames

Corrosion and durability
The thermal break itself is not a corrosion barrier, but modern thermally-broken systems are engineered to ensure long-term durability and drainage/weep solutions comparable to non-thermal systems.

Improved energy efficiency
Thermally broken frames reduce conductive heat loss through the frame. When used with double glazing and appropriate seals, they lower the overall window U-value — meaning less energy wasted heating or cooling a building.

Reduced condensation risk
Because interior frame temperatures are higher (less cold conduction from outside), condensation on the inside face of the frame is reduced, which helps prevent mould and moisture damage.

Increased occupant comfort
Less cold-radiant feeling near windows and doors in winter, and fewer hot spots in summer — leading to fewer drafts and a more consistent internal temperature.

Better acoustic performance
While glazing is the biggest factor for sound reduction, thermal breaks can contribute a small improvement by reducing the direct metal path that transmits vibration and sound.

Typical performance

Below is an illustrative comparison showing example whole-window U-values (W/m²K) to demonstrate how thermally broken frames can improve performance. These numbers are for demonstration only — actual tested U-values vary with profile design, glass specification, spacer, seal type and installation details.

Example:

• Single-glazed (non-thermal aluminium): ~5.5 W/m²K
• Double-glazed (non-thermal aluminium): ~3.0 W/m²K
• Double-glazed with thermally-broken frame: ~1.8 W/m²K

Note: Always rely on certified test data (e.g., AS2047 / WERS ratings or manufacturer test reports) when specifying windows for regulatory compliance or energy modelling.

Materials & Construction

• Common thermal break material: Polyamide (reinforced) or similar high-performance polymers designed to carry structural loads while providing low thermal conductivity.
• Seal and spacer choices: Glass spacers (warm edge), low-E coatings, and sealed units (IGUs) all work together with the frame thermal break to determine overall performance.
• Installation matters: Even the best thermally broken frame will underperform if poorly installed — thermal bridging at the interface between wall and frame must be addressed with correct flashing, insulation and sealant.

Condensation, comfort, and compliance

For condensation control and condensation risk modeling, thermally broken frames are a practical measure. They are often required in higher-performance building envelopes and are commonly specified for energy-efficient builds, passive house adaptations, and commercial facades where thermal performance is a priority.

Choosing the right option for your project

• For retrofit projects where budget is tight but energy savings are desired, upgrading to double glazing plus thermally broken frames provides a strong improvement vs. non-thermal frames.
• For new builds or high-performance renovations, choose tested systems (and request WERS / lab-tested whole-window U-values) to meet or exceed local code requirements and your comfort goals.

Quick FAQ

Q — Are thermally broken windows more expensive?
A — Yes, typically slightly higher initial cost than non-thermal aluminium frames, but they yield energy savings and comfort benefits that often offset the premium over time.

Q — Do they need special maintenance?
A — No special maintenance beyond normal cleaning and periodic checking of seals and drainage channels; the thermal break material is designed for long-term service.

Q — Can I use thermally broken doors as well?
A — Absolutely. Thermally broken designs are available for sliding doors, casement doors, and many other door types to improve thermal performance across the whole opening.

Want product-specific performance data?

If you’d like, we can add your product’s tested performance numbers (U-values, SHGC, condensation resistance) into the article and regenerate the comparison chart using your actual data. Send your test figures or the product spec sheets and I’ll update the graphs and images to match.