The 2026 Showdown: Korniche vs Brett Martin Roof Lanterns Compared

The residential glazing market in 2026 is no longer just about aesthetics. Approved Document L has tightened thermal standards, energy bills remain a key concern for buyers, and the roof lantern has become one of the most scrutinised elements of any extension project. Homeowners are no longer simply asking "which looks better?" - they are asking "which performs better, lasts longer, and adds the most value?" 

This guide gives you the definitive, technical comparison of Korniche vs Brett Martin roof lanterns in 2026. We cover frame engineering, glazing specifications, U-values, installation complexity, pricing, and exactly who each product is built for. Whether you are a homeowner planning a kitchen extension or a contractor specifying for a client, this is the only comparison guide you need. 

1. Brand Engineering: What You Are Actually Buying 

Korniche - The Slim-Line Specialist 

Korniche entered the UK roof lantern market with one goal: to engineer the slimmest, most thermally efficient aluminium lantern available at scale. Their signature feature is the ultra-narrow ridge and rafter profile - with as little as 38mm of visible aluminium - which maximises the glazed area and the volume of natural light entering the space below. 

The frame uses a polyamide thermal break throughout, achieving a whole-unit U-value of approximately 1.0 W/m²K. This comfortably exceeds the 2026 Approved Document L requirement of 1.2 W/m²K for replacement glazing and 1.1 W/m²K for new extension glazing. 

The Korniche one-piece base frame is a genuine installation advantage. It eliminates the traditional multi-piece kerb assembly, reducing on-site time and the risk of misalignment or water ingress at the junction. 

Brett Martin - The Proven British Standard 

Brett Martin is a Northern Irish manufacturer with decades of experience across polycarbonate rooflights, flat glass systems, and aluminium roof lanterns. The Brett Martin aluminium roof lantern uses a thermally broken frame to achieve a U-value of approximately 1.2 W/m²K - fully compliant with 2026 Building Regulations. 

Where Brett Martin differentiates itself is breadth. The system offers both double-glazed glass units and polycarbonate glazing options, making it genuinely versatile across habitable and non-habitable spaces. Stock sizes are available with lead times of one to two weeks, which is a significant advantage on projects with tight programme dates. 

2. Technical Specification Comparison 

 3. How the Thermal Break Works in Both Systems? 

Both Korniche and Brett Martin use a polyamide thermal break - a strip of low-conductivity material bonded between the inner and outer aluminium sections of the frame. Aluminium has a thermal conductivity of approximately 160 W/m²K, meaning without intervention, cold outdoor air would transfer directly through the frame into your home, causing surface condensation and significant heat loss. 

The thermal break reduces this transfer rate to less than 0.3 W/m²K across the barrier itself, keeping the inner frame surface close to room temperature. 

For a deeper understanding of glazing performance, read our guide on triple glazed rooflights, which pushes U-values even further with a third pane and argon fill. 

4. Installation Complexity and Trade Considerations 

Korniche is designed to be installer-friendly. The single-piece base frame means the kerb, upstand, and flashing are integrated — reducing the number of joints and the potential for water ingress at the critical roof-to-lantern junction. For trade professionals working on tight schedules, this is a real-world advantage. 

Brett Martin uses a conventional multi-component installation method familiar to most roofers and builders. There is no learning curve if your team has installed any aluminium roof lantern before. Parts are also widely available, making future maintenance straightforward. 

5. Pricing and Value Assessment